[PATCH v3 0/3] misc: fastrpc: Add polling mode support

[PATCH v3 0/3] misc: fastrpc: Add polling mode support

[Ekansh Gupta]

This patch series adds polling mode feature that have been missing in
upstream FastRPC driver.

- Add changes to move fdlist to ctx structure to avoid code duplicacy.
- Update context mask to support polling mode.
- Add changes to support polling feature.

Userspace change: https://github.com/qualcomm/fastrpc/pull/258
Patch [v2]: https://lore.kernel.org/all/20251106050839.3091707-1-ekansh.gupta@oss.qualcomm.com/

Changes in v3:
  - Resolve compilation warning.

Changes in v2:
  - Added comments and fixed commit text.
  - Defined context id position as a macro.
  - Added new IOCTL to control polling mode as always enabling
    it might cause excess power consumption.
  - Cleaned up polling mode implementation.

Ekansh Gupta (3):
  misc: fastrpc: Move fdlist to invoke context structure
  misc: fastrpc: Update context ID mask for polling mode support
  misc: fastrpc: Add polling mode support for fastRPC driver

 drivers/misc/fastrpc.c      | 163 +++++++++++++++++++++++++++++++-----
 include/uapi/misc/fastrpc.h |   9 ++
 2 files changed, 150 insertions(+), 22 deletions(-)

-- 
2.34.1

[PATCH v3 1/3] misc: fastrpc: Move fdlist to invoke context structure

[Ekansh Gupta]

The fdlist is currently part of the meta buffer, computed during
put_args. This leads to code duplication when preparing and reading
critical meta buffer contents used by the FastRPC driver.

Move fdlist to the invoke context structure to improve maintainability
and reduce redundancy. This centralizes its handling and simplifies
meta buffer preparation and reading logic.

Signed-off-by: Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>
---
 drivers/misc/fastrpc.c | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index ee652ef01534..679cd8997a00 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -233,6 +233,7 @@ struct fastrpc_invoke_ctx {
 	int pid;
 	int client_id;
 	u32 sc;
+	u64 *fdlist;
 	u32 *crc;
 	u64 ctxid;
 	u64 msg_sz;
@@ -987,6 +988,7 @@ static int fastrpc_get_args(u32 kernel, struct fastrpc_invoke_ctx *ctx)
 	rpra = ctx->buf->virt;
 	list = fastrpc_invoke_buf_start(rpra, ctx->nscalars);
 	pages = fastrpc_phy_page_start(list, ctx->nscalars);
+	ctx->fdlist = (u64 *)(pages + ctx->nscalars);
 	args = (uintptr_t)ctx->buf->virt + metalen;
 	rlen = pkt_size - metalen;
 	ctx->rpra = rpra;
@@ -1089,18 +1091,10 @@ static int fastrpc_put_args(struct fastrpc_invoke_ctx *ctx,
 	union fastrpc_remote_arg *rpra = ctx->rpra;
 	struct fastrpc_user *fl = ctx->fl;
 	struct fastrpc_map *mmap = NULL;
-	struct fastrpc_invoke_buf *list;
-	struct fastrpc_phy_page *pages;
-	u64 *fdlist;
-	int i, inbufs, outbufs, handles;
+	int i, inbufs;
 	int ret = 0;
 
 	inbufs = REMOTE_SCALARS_INBUFS(ctx->sc);
-	outbufs = REMOTE_SCALARS_OUTBUFS(ctx->sc);
-	handles = REMOTE_SCALARS_INHANDLES(ctx->sc) + REMOTE_SCALARS_OUTHANDLES(ctx->sc);
-	list = fastrpc_invoke_buf_start(rpra, ctx->nscalars);
-	pages = fastrpc_phy_page_start(list, ctx->nscalars);
-	fdlist = (uint64_t *)(pages + inbufs + outbufs + handles);
 
 	for (i = inbufs; i < ctx->nbufs; ++i) {
 		if (!ctx->maps[i]) {
@@ -1122,9 +1116,9 @@ static int fastrpc_put_args(struct fastrpc_invoke_ctx *ctx,
 cleanup_fdlist:
 	/* Clean up fdlist which is updated by DSP */
 	for (i = 0; i < FASTRPC_MAX_FDLIST; i++) {
-		if (!fdlist[i])
+		if (!ctx->fdlist[i])
 			break;
-		if (!fastrpc_map_lookup(fl, (int)fdlist[i], &mmap))
+		if (!fastrpc_map_lookup(fl, (int)ctx->fdlist[i], &mmap))
 			fastrpc_map_put(mmap);
 	}
 
-- 
2.34.1

[PATCH v3 2/3] misc: fastrpc: Update context ID mask for polling mode support

[Ekansh Gupta]

Current FastRPC message context uses a 12-bit mask where the upper
8 bits are context ID from idr_alloc_cyclic and the lower 4 bits
represent PD type. This design works for normal FastRPC calls but
doesn't work as expected for polling mode. To enable polling mode
support from DSP(DSP writes to poll memory), DSP expects a 16-bit
context where the upper 8 bits are context ID, the lower 4 bits are
PD type and the 5th bit from the end denotes async mode(not yet
upstreamed). If this bit is set, DSP disables polling. With the
current design, odd context IDs set this bit, causing DSP to skip
poll memory updates. Update the context mask to ensure a hole
which won't get populated, ensuring polling mode works as expected.
This is not a bug and the change is added to support polling mode.

Signed-off-by: Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>
---
 drivers/misc/fastrpc.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index 679cd8997a00..ccba3b6dfdfa 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -37,7 +37,8 @@
 #define FASTRPC_CTX_MAX (256)
 #define FASTRPC_INIT_HANDLE	1
 #define FASTRPC_DSP_UTILITIES_HANDLE	2
-#define FASTRPC_CTXID_MASK (0xFF0)
+#define FASTRPC_CTXID_MASK (0xFF00)
+#define FASTRPC_CTXID_POS (8)
 #define INIT_FILELEN_MAX (2 * 1024 * 1024)
 #define INIT_FILE_NAMELEN_MAX (128)
 #define FASTRPC_DEVICE_NAME	"fastrpc"
@@ -489,7 +490,7 @@ static void fastrpc_context_free(struct kref *ref)
 		fastrpc_buf_free(ctx->buf);
 
 	spin_lock_irqsave(&cctx->lock, flags);
-	idr_remove(&cctx->ctx_idr, ctx->ctxid >> 4);
+	idr_remove(&cctx->ctx_idr, ctx->ctxid >> FASTRPC_CTXID_POS);
 	spin_unlock_irqrestore(&cctx->lock, flags);
 
 	kfree(ctx->maps);
@@ -625,7 +626,7 @@ static struct fastrpc_invoke_ctx *fastrpc_context_alloc(
 		spin_unlock_irqrestore(&cctx->lock, flags);
 		goto err_idr;
 	}
-	ctx->ctxid = ret << 4;
+	ctx->ctxid = ret << FASTRPC_CTXID_POS;
 	spin_unlock_irqrestore(&cctx->lock, flags);
 
 	kref_init(&ctx->refcount);
@@ -2451,7 +2452,7 @@ static int fastrpc_rpmsg_callback(struct rpmsg_device *rpdev, void *data,
 	if (len < sizeof(*rsp))
 		return -EINVAL;
 
-	ctxid = ((rsp->ctx & FASTRPC_CTXID_MASK) >> 4);
+	ctxid = ((rsp->ctx & FASTRPC_CTXID_MASK) >> FASTRPC_CTXID_POS);
 
 	spin_lock_irqsave(&cctx->lock, flags);
 	ctx = idr_find(&cctx->ctx_idr, ctxid);
-- 
2.34.1

[PATCH v3 3/3] misc: fastrpc: Add polling mode support for fastRPC driver

[Ekansh Gupta]

For any remote call to DSP, after sending an invocation message,
fastRPC driver waits for glink response and during this time the
CPU can go into low power modes. This adds latency to overall fastrpc
call as CPU wakeup and scheduling latencies are included. Add polling
mode support with which fastRPC driver will poll continuously on a
memory after sending a message to remote subsystem which will eliminate
CPU wakeup and scheduling latencies and reduce fastRPC overhead. Poll
mode can be enabled by user by making a remote_handle64_control request.

Signed-off-by: Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>
---
 drivers/misc/fastrpc.c      | 138 ++++++++++++++++++++++++++++++++++--
 include/uapi/misc/fastrpc.h |   9 +++
 2 files changed, 140 insertions(+), 7 deletions(-)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index ccba3b6dfdfa..60de9dcb9815 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -22,6 +22,8 @@
 #include <linux/firmware/qcom/qcom_scm.h>
 #include <uapi/misc/fastrpc.h>
 #include <linux/of_reserved_mem.h>
+#include <linux/compiler.h>
+#include <linux/iopoll.h>
 
 #define ADSP_DOMAIN_ID (0)
 #define MDSP_DOMAIN_ID (1)
@@ -37,6 +39,7 @@
 #define FASTRPC_CTX_MAX (256)
 #define FASTRPC_INIT_HANDLE	1
 #define FASTRPC_DSP_UTILITIES_HANDLE	2
+#define FASTRPC_MAX_STATIC_HANDLE (20)
 #define FASTRPC_CTXID_MASK (0xFF00)
 #define FASTRPC_CTXID_POS (8)
 #define INIT_FILELEN_MAX (2 * 1024 * 1024)
@@ -106,6 +109,12 @@
 
 #define miscdev_to_fdevice(d) container_of(d, struct fastrpc_device, miscdev)
 
+/* Poll response number from remote processor for call completion */
+#define FASTRPC_POLL_RESPONSE (0xdecaf)
+
+/* Polling mode timeout limit */
+#define FASTRPC_POLL_MAX_TIMEOUT_US (10000)
+
 struct fastrpc_phy_page {
 	u64 addr;		/* physical address */
 	u64 size;		/* size of contiguous region */
@@ -236,8 +245,14 @@ struct fastrpc_invoke_ctx {
 	u32 sc;
 	u64 *fdlist;
 	u32 *crc;
+	/* Poll memory that DSP updates */
+	u32 *poll;
 	u64 ctxid;
 	u64 msg_sz;
+	/* work done status flag */
+	bool is_work_done;
+	/* process updates poll memory instead of glink response */
+	bool is_polled;
 	struct kref refcount;
 	struct list_head node; /* list of ctxs */
 	struct completion work;
@@ -301,6 +316,8 @@ struct fastrpc_user {
 	int client_id;
 	int pd;
 	bool is_secure_dev;
+	/* Flags poll mode state */
+	bool poll_mode;
 	/* Lock for lists */
 	spinlock_t lock;
 	/* lock for allocations */
@@ -894,7 +911,8 @@ static int fastrpc_get_meta_size(struct fastrpc_invoke_ctx *ctx)
 		sizeof(struct fastrpc_invoke_buf) +
 		sizeof(struct fastrpc_phy_page)) * ctx->nscalars +
 		sizeof(u64) * FASTRPC_MAX_FDLIST +
-		sizeof(u32) * FASTRPC_MAX_CRCLIST;
+		sizeof(u32) * FASTRPC_MAX_CRCLIST +
+		sizeof(u32);
 
 	return size;
 }
@@ -990,6 +1008,7 @@ static int fastrpc_get_args(u32 kernel, struct fastrpc_invoke_ctx *ctx)
 	list = fastrpc_invoke_buf_start(rpra, ctx->nscalars);
 	pages = fastrpc_phy_page_start(list, ctx->nscalars);
 	ctx->fdlist = (u64 *)(pages + ctx->nscalars);
+	ctx->poll = (u32 *)(ctx->fdlist + FASTRPC_MAX_FDLIST + FASTRPC_MAX_CRCLIST);
 	args = (uintptr_t)ctx->buf->virt + metalen;
 	rlen = pkt_size - metalen;
 	ctx->rpra = rpra;
@@ -1158,6 +1177,75 @@ static int fastrpc_invoke_send(struct fastrpc_session_ctx *sctx,
 
 }
 
+static inline u32 fastrpc_poll_op(void *p)
+{
+	struct fastrpc_invoke_ctx *ctx = p;
+
+	dma_rmb();
+	return READ_ONCE(*ctx->poll);
+}
+
+static int poll_for_remote_response(struct fastrpc_invoke_ctx *ctx)
+{
+	u32 val;
+	int ret;
+
+	/*
+	 * Poll until DSP writes FASTRPC_POLL_RESPONSE into *ctx->poll
+	 * or until another path marks the work done.
+	 */
+	ret = read_poll_timeout_atomic(fastrpc_poll_op, val,
+				       (val == FASTRPC_POLL_RESPONSE) ||
+				       ctx->is_work_done, 1,
+				       FASTRPC_POLL_MAX_TIMEOUT_US, false, ctx);
+
+	if (!ret && val == FASTRPC_POLL_RESPONSE) {
+		ctx->is_work_done = true;
+		ctx->retval = 0;
+	}
+
+	if (ret == -ETIMEDOUT)
+		ret = -EIO;
+
+	return ret;
+}
+
+static inline int fastrpc_wait_for_response(struct fastrpc_invoke_ctx *ctx,
+					    u32 kernel)
+{
+	int err = 0;
+
+	if (kernel) {
+		if (!wait_for_completion_timeout(&ctx->work, 10 * HZ))
+			err = -ETIMEDOUT;
+	} else {
+		err = wait_for_completion_interruptible(&ctx->work);
+	}
+
+	return err;
+}
+
+static int fastrpc_wait_for_completion(struct fastrpc_invoke_ctx *ctx,
+				       u32 kernel)
+{
+	int err;
+
+	do {
+		if (ctx->is_polled) {
+			err = poll_for_remote_response(ctx);
+			/* If polling timed out, move to normal response mode */
+			if (err)
+				ctx->is_polled = false;
+		} else {
+			err = fastrpc_wait_for_response(ctx, kernel);
+			if (err)
+				return err;
+		}
+	} while (!ctx->is_work_done);
+
+	return err;
+}
+
 static int fastrpc_internal_invoke(struct fastrpc_user *fl,  u32 kernel,
 				   u32 handle, u32 sc,
 				   struct fastrpc_invoke_args *args)
@@ -1193,16 +1281,25 @@ static int fastrpc_internal_invoke(struct fastrpc_user *fl,  u32 kernel,
 	if (err)
 		goto bail;
 
-	if (kernel) {
-		if (!wait_for_completion_timeout(&ctx->work, 10 * HZ))
-			err = -ETIMEDOUT;
-	} else {
-		err = wait_for_completion_interruptible(&ctx->work);
-	}
+	/*
+	 * Set message context as polled if the call is for a user PD
+	 * dynamic module and user has enabled poll mode.
+	 */
+	if (handle > FASTRPC_MAX_STATIC_HANDLE && fl->pd == USER_PD &&
+	    fl->poll_mode)
+		ctx->is_polled = true;
+
+	err = fastrpc_wait_for_completion(ctx, kernel);
 
 	if (err)
 		goto bail;
 
+	if (!ctx->is_work_done) {
+		err = -ETIMEDOUT;
+		dev_dbg(fl->sctx->dev, "Invalid workdone state for handle 0x%x, sc 0x%x\n",
+			handle, sc);
+		goto bail;
+	}
 	/* make sure that all memory writes by DSP are seen by CPU */
 	dma_rmb();
 	/* populate all the output buffers with results */
@@ -1780,6 +1877,29 @@ static int fastrpc_get_info_from_kernel(struct fastrpc_ioctl_capability *cap,
 	return 0;
 }
 
+static int fastrpc_set_option(struct fastrpc_user *fl, char __user *argp)
+{
+	struct fastrpc_ioctl_set_option opt = {0};
+	int i;
+
+	if (copy_from_user(&opt, argp, sizeof(opt)))
+		return -EFAULT;
+
+	for (i = 0; i < ARRAY_SIZE(opt.reserved); i++) {
+		if (opt.reserved[i] != 0)
+			return -EINVAL;
+	}
+	if (opt.req != FASTRPC_POLL_MODE)
+		return -EINVAL;
+
+	if (opt.enable)
+		fl->poll_mode = true;
+	else
+		fl->poll_mode = false;
+
+	return 0;
+}
+
 static int fastrpc_get_dsp_info(struct fastrpc_user *fl, char __user *argp)
 {
 	struct fastrpc_ioctl_capability cap = {0};
@@ -2134,6 +2254,9 @@ static long fastrpc_device_ioctl(struct file *file, unsigned int cmd,
 	case FASTRPC_IOCTL_MEM_UNMAP:
 		err = fastrpc_req_mem_unmap(fl, argp);
 		break;
+	case FASTRPC_IOCTL_SET_OPTION:
+		err = fastrpc_set_option(fl, argp);
+		break;
 	case FASTRPC_IOCTL_GET_DSP_INFO:
 		err = fastrpc_get_dsp_info(fl, argp);
 		break;
@@ -2465,6 +2588,7 @@ static int fastrpc_rpmsg_callback(struct rpmsg_device *rpdev, void *data,
 
 	ctx->retval = rsp->retval;
 	complete(&ctx->work);
+	ctx->is_work_done = true;
 
 	/*
 	 * The DMA buffer associated with the context cannot be freed in
diff --git a/include/uapi/misc/fastrpc.h b/include/uapi/misc/fastrpc.h
index c6e2925f47e6..6c1375ba0042 100644
--- a/include/uapi/misc/fastrpc.h
+++ b/include/uapi/misc/fastrpc.h
@@ -16,6 +16,7 @@
 #define FASTRPC_IOCTL_INIT_CREATE_STATIC _IOWR('R', 9, struct fastrpc_init_create_static)
 #define FASTRPC_IOCTL_MEM_MAP		_IOWR('R', 10, struct fastrpc_mem_map)
 #define FASTRPC_IOCTL_MEM_UNMAP		_IOWR('R', 11, struct fastrpc_mem_unmap)
+#define FASTRPC_IOCTL_SET_OPTION	_IOWR('R', 12, struct fastrpc_ioctl_set_option)
 #define FASTRPC_IOCTL_GET_DSP_INFO	_IOWR('R', 13, struct fastrpc_ioctl_capability)
 
 /**
@@ -66,6 +67,8 @@ enum fastrpc_proc_attr {
 
 /* Fastrpc attribute for memory protection of buffers */
 #define FASTRPC_ATTR_SECUREMAP	(1)
+/* Set option request ID to enable poll mode */
+#define FASTRPC_POLL_MODE	(1)
 
 struct fastrpc_invoke_args {
 	__u64 ptr;
@@ -133,6 +136,12 @@ struct fastrpc_mem_unmap {
 	__s32 reserved[5];
 };
 
+struct fastrpc_ioctl_set_option {
+	__u32 req;		/* request id */
+	__u32 enable;	/* enable flag */
+	__s32 reserved[6];
+};
+
 struct fastrpc_ioctl_capability {
 	__u32 unused; /* deprecated, ignored by the kernel */
 	__u32 attribute_id;
-- 
2.34.1

Re: [PATCH v3 2/3] misc: fastrpc: Update context ID mask for polling mode support

[Dmitry Baryshkov]

On Thu, Nov 13, 2025 at 12:11:10PM +0530, Ekansh Gupta wrote:
> Current FastRPC message context uses a 12-bit mask where the upper
> 8 bits are context ID from idr_alloc_cyclic and the lower 4 bits
> represent PD type. This design works for normal FastRPC calls but
> doesn't work as expected for polling mode.

Doesn't work why / how?

> To enable polling mode
> support from DSP(DSP writes to poll memory), DSP expects a 16-bit
> context where the upper 8 bits are context ID, the lower 4 bits are
> PD type and the 5th bit from the end denotes async mode(not yet

What's in the middle between bits 5 and 8?

> upstreamed). If this bit is set, DSP disables polling. With the
> current design, odd context IDs set this bit, causing DSP to skip
> poll memory updates. Update the context mask to ensure a hole
> which won't get populated, ensuring polling mode works as expected.
> This is not a bug and the change is added to support polling mode.
> 
> Signed-off-by: Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>
> ---
>  drivers/misc/fastrpc.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
> index 679cd8997a00..ccba3b6dfdfa 100644
> --- a/drivers/misc/fastrpc.c
> +++ b/drivers/misc/fastrpc.c
> @@ -37,7 +37,8 @@
>  #define FASTRPC_CTX_MAX (256)
>  #define FASTRPC_INIT_HANDLE	1
>  #define FASTRPC_DSP_UTILITIES_HANDLE	2
> -#define FASTRPC_CTXID_MASK (0xFF0)
> +#define FASTRPC_CTXID_MASK (0xFF00)
> +#define FASTRPC_CTXID_POS (8)

Use FIELD_PREP instead.

>  #define INIT_FILELEN_MAX (2 * 1024 * 1024)
>  #define INIT_FILE_NAMELEN_MAX (128)
>  #define FASTRPC_DEVICE_NAME	"fastrpc"
> @@ -489,7 +490,7 @@ static void fastrpc_context_free(struct kref *ref)
>  		fastrpc_buf_free(ctx->buf);
>  
>  	spin_lock_irqsave(&cctx->lock, flags);
> -	idr_remove(&cctx->ctx_idr, ctx->ctxid >> 4);
> +	idr_remove(&cctx->ctx_idr, ctx->ctxid >> FASTRPC_CTXID_POS);
>  	spin_unlock_irqrestore(&cctx->lock, flags);
>  
>  	kfree(ctx->maps);
> @@ -625,7 +626,7 @@ static struct fastrpc_invoke_ctx *fastrpc_context_alloc(
>  		spin_unlock_irqrestore(&cctx->lock, flags);
>  		goto err_idr;
>  	}
> -	ctx->ctxid = ret << 4;
> +	ctx->ctxid = ret << FASTRPC_CTXID_POS;
>  	spin_unlock_irqrestore(&cctx->lock, flags);
>  
>  	kref_init(&ctx->refcount);
> @@ -2451,7 +2452,7 @@ static int fastrpc_rpmsg_callback(struct rpmsg_device *rpdev, void *data,
>  	if (len < sizeof(*rsp))
>  		return -EINVAL;
>  
> -	ctxid = ((rsp->ctx & FASTRPC_CTXID_MASK) >> 4);
> +	ctxid = ((rsp->ctx & FASTRPC_CTXID_MASK) >> FASTRPC_CTXID_POS);
>  
>  	spin_lock_irqsave(&cctx->lock, flags);
>  	ctx = idr_find(&cctx->ctx_idr, ctxid);
> -- 
> 2.34.1
> 

-- 
With best wishes
Dmitry

Re: [PATCH v3 3/3] misc: fastrpc: Add polling mode support for fastRPC driver

[Dmitry Baryshkov]

On Thu, Nov 13, 2025 at 12:11:11PM +0530, Ekansh Gupta wrote:
> For any remote call to DSP, after sending an invocation message,
> fastRPC driver waits for glink response and during this time the
> CPU can go into low power modes. This adds latency to overall fastrpc
> call as CPU wakeup and scheduling latencies are included. Add polling
> mode support with which fastRPC driver will poll continuously on a
> memory after sending a message to remote subsystem which will eliminate
> CPU wakeup and scheduling latencies and reduce fastRPC overhead. Poll
> mode can be enabled by user by making a remote_handle64_control request.

Which request?? I thought it's enabled by making an IOCTL.

> 
> Signed-off-by: Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>
> ---
>  drivers/misc/fastrpc.c      | 138 ++++++++++++++++++++++++++++++++++--
>  include/uapi/misc/fastrpc.h |   9 +++
>  2 files changed, 140 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
> index ccba3b6dfdfa..60de9dcb9815 100644
> --- a/drivers/misc/fastrpc.c
> +++ b/drivers/misc/fastrpc.c
> @@ -22,6 +22,8 @@
>  #include <linux/firmware/qcom/qcom_scm.h>
>  #include <uapi/misc/fastrpc.h>
>  #include <linux/of_reserved_mem.h>
> +#include <linux/compiler.h>
> +#include <linux/iopoll.h>
>  
>  #define ADSP_DOMAIN_ID (0)
>  #define MDSP_DOMAIN_ID (1)
> @@ -37,6 +39,7 @@
>  #define FASTRPC_CTX_MAX (256)
>  #define FASTRPC_INIT_HANDLE	1
>  #define FASTRPC_DSP_UTILITIES_HANDLE	2
> +#define FASTRPC_MAX_STATIC_HANDLE (20)
>  #define FASTRPC_CTXID_MASK (0xFF00)
>  #define FASTRPC_CTXID_POS (8)
>  #define INIT_FILELEN_MAX (2 * 1024 * 1024)
> @@ -106,6 +109,12 @@
>  
>  #define miscdev_to_fdevice(d) container_of(d, struct fastrpc_device, miscdev)
>  
> +/* Poll response number from remote processor for call completion */
> +#define FASTRPC_POLL_RESPONSE (0xdecaf)
> +
> +/* Polling mode timeout limit */
> +#define FASTRPC_POLL_MAX_TIMEOUT_US (10000)
> +
>  struct fastrpc_phy_page {
>  	u64 addr;		/* physical address */
>  	u64 size;		/* size of contiguous region */
> @@ -236,8 +245,14 @@ struct fastrpc_invoke_ctx {
>  	u32 sc;
>  	u64 *fdlist;
>  	u32 *crc;
> +	/* Poll memory that DSP updates */
> +	u32 *poll;
>  	u64 ctxid;
>  	u64 msg_sz;
> +	/* work done status flag */
> +	bool is_work_done;
> +	/* process updates poll memory instead of glink response */
> +	bool is_polled;
>  	struct kref refcount;
>  	struct list_head node; /* list of ctxs */
>  	struct completion work;
> @@ -301,6 +316,8 @@ struct fastrpc_user {
>  	int client_id;
>  	int pd;
>  	bool is_secure_dev;
> +	/* Flags poll mode state */
> +	bool poll_mode;
>  	/* Lock for lists */
>  	spinlock_t lock;
>  	/* lock for allocations */
> @@ -894,7 +911,8 @@ static int fastrpc_get_meta_size(struct fastrpc_invoke_ctx *ctx)
>  		sizeof(struct fastrpc_invoke_buf) +
>  		sizeof(struct fastrpc_phy_page)) * ctx->nscalars +
>  		sizeof(u64) * FASTRPC_MAX_FDLIST +
> -		sizeof(u32) * FASTRPC_MAX_CRCLIST;
> +		sizeof(u32) * FASTRPC_MAX_CRCLIST +
> +		sizeof(u32);
>  
>  	return size;
>  }
> @@ -990,6 +1008,7 @@ static int fastrpc_get_args(u32 kernel, struct fastrpc_invoke_ctx *ctx)
>  	list = fastrpc_invoke_buf_start(rpra, ctx->nscalars);
>  	pages = fastrpc_phy_page_start(list, ctx->nscalars);
>  	ctx->fdlist = (u64 *)(pages + ctx->nscalars);
> +	ctx->poll = (u32 *)(ctx->fdlist + FASTRPC_MAX_FDLIST + FASTRPC_MAX_CRCLIST);
>  	args = (uintptr_t)ctx->buf->virt + metalen;
>  	rlen = pkt_size - metalen;
>  	ctx->rpra = rpra;
> @@ -1158,6 +1177,75 @@ static int fastrpc_invoke_send(struct fastrpc_session_ctx *sctx,
>  
>  }
>  
> +static inline u32 fastrpc_poll_op(void *p)
> +{
> +	struct fastrpc_invoke_ctx *ctx = p;
> +
> +	dma_rmb();
> +	return READ_ONCE(*ctx->poll);

How does this work with caches? Does it require dma-coherent fastrpc
devices?

> +}
> +
> +static int poll_for_remote_response(struct fastrpc_invoke_ctx *ctx)
> +{
> +	u32 val;
> +	int ret;
> +
> +	/*
> +	 * Poll until DSP writes FASTRPC_POLL_RESPONSE into *ctx->poll
> +	 * or until another path marks the work done.
> +	 */
> +	ret = read_poll_timeout_atomic(fastrpc_poll_op, val,
> +				       (val == FASTRPC_POLL_RESPONSE) ||
> +				       ctx->is_work_done, 1,
> +				       FASTRPC_POLL_MAX_TIMEOUT_US, false, ctx);
> +
> +	if (!ret && val == FASTRPC_POLL_RESPONSE) {
> +		ctx->is_work_done = true;
> +		ctx->retval = 0;
> +	}
> +
> +	if (ret == -ETIMEDOUT)
> +		ret = -EIO;
> +
> +	return ret;
> +}
> +
> +static inline int fastrpc_wait_for_response(struct fastrpc_invoke_ctx *ctx,
> +					    u32 kernel)
> +{
> +	int err = 0;
> +
> +	if (kernel) {
> +		if (!wait_for_completion_timeout(&ctx->work, 10 * HZ))
> +			err = -ETIMEDOUT;
> +	} else {
> +		err = wait_for_completion_interruptible(&ctx->work);
> +	}
> +
> +	return err;
> +}
> +
> +static int fastrpc_wait_for_completion(struct fastrpc_invoke_ctx *ctx,
> +				       u32 kernel)
> +{
> +	int err;
> +
> +	do {
> +		if (ctx->is_polled) {
> +			err = poll_for_remote_response(ctx);
> +			/* If polling timed out, move to normal response mode */
> +			if (err)
> +				ctx->is_polled = false;
> +		} else {
> +			err = fastrpc_wait_for_response(ctx, kernel);
> +			if (err)
> +				return err;
> +		}
> +	} while (!ctx->is_work_done);
> +
> +	return err;
> +}
> +
>  static int fastrpc_internal_invoke(struct fastrpc_user *fl,  u32 kernel,
>  				   u32 handle, u32 sc,
>  				   struct fastrpc_invoke_args *args)
> @@ -1193,16 +1281,25 @@ static int fastrpc_internal_invoke(struct fastrpc_user *fl,  u32 kernel,
>  	if (err)
>  		goto bail;
>  
> -	if (kernel) {
> -		if (!wait_for_completion_timeout(&ctx->work, 10 * HZ))
> -			err = -ETIMEDOUT;
> -	} else {
> -		err = wait_for_completion_interruptible(&ctx->work);
> -	}
> +	/*
> +	 * Set message context as polled if the call is for a user PD
> +	 * dynamic module and user has enabled poll mode.
> +	 */
> +	if (handle > FASTRPC_MAX_STATIC_HANDLE && fl->pd == USER_PD &&
> +	    fl->poll_mode)
> +		ctx->is_polled = true;
> +
> +	err = fastrpc_wait_for_completion(ctx, kernel);
>  
>  	if (err)
>  		goto bail;
>  
> +	if (!ctx->is_work_done) {
> +		err = -ETIMEDOUT;
> +		dev_dbg(fl->sctx->dev, "Invalid workdone state for handle 0x%x, sc 0x%x\n",
> +			handle, sc);
> +		goto bail;
> +	}
>  	/* make sure that all memory writes by DSP are seen by CPU */
>  	dma_rmb();
>  	/* populate all the output buffers with results */
> @@ -1780,6 +1877,29 @@ static int fastrpc_get_info_from_kernel(struct fastrpc_ioctl_capability *cap,
>  	return 0;
>  }
>  
> +static int fastrpc_set_option(struct fastrpc_user *fl, char __user *argp)
> +{
> +	struct fastrpc_ioctl_set_option opt = {0};
> +	int i;
> +
> +	if (copy_from_user(&opt, argp, sizeof(opt)))
> +		return -EFAULT;
> +
> +	for (i = 0; i < ARRAY_SIZE(opt.reserved); i++) {
> +		if (opt.reserved[i] != 0)
> +			return -EINVAL;
> +	}

Empty line.

> +	if (opt.req != FASTRPC_POLL_MODE)
> +		return -EINVAL;
> +
> +	if (opt.enable)
> +		fl->poll_mode = true;
> +	else
> +		fl->poll_mode = false;
> +
> +	return 0;
> +}
> +
>  static int fastrpc_get_dsp_info(struct fastrpc_user *fl, char __user *argp)
>  {
>  	struct fastrpc_ioctl_capability cap = {0};
> @@ -2134,6 +2254,9 @@ static long fastrpc_device_ioctl(struct file *file, unsigned int cmd,
>  	case FASTRPC_IOCTL_MEM_UNMAP:
>  		err = fastrpc_req_mem_unmap(fl, argp);
>  		break;
> +	case FASTRPC_IOCTL_SET_OPTION:
> +		err = fastrpc_set_option(fl, argp);
> +		break;
>  	case FASTRPC_IOCTL_GET_DSP_INFO:
>  		err = fastrpc_get_dsp_info(fl, argp);
>  		break;
> @@ -2465,6 +2588,7 @@ static int fastrpc_rpmsg_callback(struct rpmsg_device *rpdev, void *data,
>  
>  	ctx->retval = rsp->retval;
>  	complete(&ctx->work);
> +	ctx->is_work_done = true;
>  
>  	/*
>  	 * The DMA buffer associated with the context cannot be freed in
> diff --git a/include/uapi/misc/fastrpc.h b/include/uapi/misc/fastrpc.h
> index c6e2925f47e6..6c1375ba0042 100644
> --- a/include/uapi/misc/fastrpc.h
> +++ b/include/uapi/misc/fastrpc.h
> @@ -16,6 +16,7 @@
>  #define FASTRPC_IOCTL_INIT_CREATE_STATIC _IOWR('R', 9, struct fastrpc_init_create_static)
>  #define FASTRPC_IOCTL_MEM_MAP		_IOWR('R', 10, struct fastrpc_mem_map)
>  #define FASTRPC_IOCTL_MEM_UNMAP		_IOWR('R', 11, struct fastrpc_mem_unmap)
> +#define FASTRPC_IOCTL_SET_OPTION	_IOWR('R', 12, struct fastrpc_ioctl_set_option)
>  #define FASTRPC_IOCTL_GET_DSP_INFO	_IOWR('R', 13, struct fastrpc_ioctl_capability)
>  
>  /**
> @@ -66,6 +67,8 @@ enum fastrpc_proc_attr {
>  
>  /* Fastrpc attribute for memory protection of buffers */
>  #define FASTRPC_ATTR_SECUREMAP	(1)
> +/* Set option request ID to enable poll mode */
> +#define FASTRPC_POLL_MODE	(1)
>  
>  struct fastrpc_invoke_args {
>  	__u64 ptr;
> @@ -133,6 +136,12 @@ struct fastrpc_mem_unmap {
>  	__s32 reserved[5];
>  };
>  
> +struct fastrpc_ioctl_set_option {
> +	__u32 req;		/* request id */
> +	__u32 enable;	/* enable flag */

s/enable/value/ ?

> +	__s32 reserved[6];

I think you got feedback from Greg regarding handling of reserved fields
few months ago. Please drop them.

> +};
> +
>  struct fastrpc_ioctl_capability {
>  	__u32 unused; /* deprecated, ignored by the kernel */
>  	__u32 attribute_id;
> -- 
> 2.34.1
> 

-- 
With best wishes
Dmitry

Re: [PATCH v3 2/3] misc: fastrpc: Update context ID mask for polling mode support

[Ekansh Gupta]

On 11/19/2025 1:59 PM, Dmitry Baryshkov wrote:
> On Thu, Nov 13, 2025 at 12:11:10PM +0530, Ekansh Gupta wrote:
>> Current FastRPC message context uses a 12-bit mask where the upper
>> 8 bits are context ID from idr_alloc_cyclic and the lower 4 bits
>> represent PD type. This design works for normal FastRPC calls but
>> doesn't work as expected for polling mode.
> Doesn't work why / how?
Explained this in the next statements, I'll rephrase this.
>
>> To enable polling mode
>> support from DSP(DSP writes to poll memory), DSP expects a 16-bit
>> context where the upper 8 bits are context ID, the lower 4 bits are
>> PD type and the 5th bit from the end denotes async mode(not yet
> What's in the middle between bits 5 and 8?
It's unused as of now.
>
>> upstreamed). If this bit is set, DSP disables polling. With the
>> current design, odd context IDs set this bit, causing DSP to skip
>> poll memory updates. Update the context mask to ensure a hole
>> which won't get populated, ensuring polling mode works as expected.
>> This is not a bug and the change is added to support polling mode.
>>
>> Signed-off-by: Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>
>> ---
>>  drivers/misc/fastrpc.c | 9 +++++----
>>  1 file changed, 5 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
>> index 679cd8997a00..ccba3b6dfdfa 100644
>> --- a/drivers/misc/fastrpc.c
>> +++ b/drivers/misc/fastrpc.c
>> @@ -37,7 +37,8 @@
>>  #define FASTRPC_CTX_MAX (256)
>>  #define FASTRPC_INIT_HANDLE	1
>>  #define FASTRPC_DSP_UTILITIES_HANDLE	2
>> -#define FASTRPC_CTXID_MASK (0xFF0)
>> +#define FASTRPC_CTXID_MASK (0xFF00)
>> +#define FASTRPC_CTXID_POS (8)
> Use FIELD_PREP instead.
Checking this, thanks
>
>>  #define INIT_FILELEN_MAX (2 * 1024 * 1024)
>>  #define INIT_FILE_NAMELEN_MAX (128)
>>  #define FASTRPC_DEVICE_NAME	"fastrpc"
>> @@ -489,7 +490,7 @@ static void fastrpc_context_free(struct kref *ref)
>>  		fastrpc_buf_free(ctx->buf);
>>  
>>  	spin_lock_irqsave(&cctx->lock, flags);
>> -	idr_remove(&cctx->ctx_idr, ctx->ctxid >> 4);
>> +	idr_remove(&cctx->ctx_idr, ctx->ctxid >> FASTRPC_CTXID_POS);
>>  	spin_unlock_irqrestore(&cctx->lock, flags);
>>  
>>  	kfree(ctx->maps);
>> @@ -625,7 +626,7 @@ static struct fastrpc_invoke_ctx *fastrpc_context_alloc(
>>  		spin_unlock_irqrestore(&cctx->lock, flags);
>>  		goto err_idr;
>>  	}
>> -	ctx->ctxid = ret << 4;
>> +	ctx->ctxid = ret << FASTRPC_CTXID_POS;
>>  	spin_unlock_irqrestore(&cctx->lock, flags);
>>  
>>  	kref_init(&ctx->refcount);
>> @@ -2451,7 +2452,7 @@ static int fastrpc_rpmsg_callback(struct rpmsg_device *rpdev, void *data,
>>  	if (len < sizeof(*rsp))
>>  		return -EINVAL;
>>  
>> -	ctxid = ((rsp->ctx & FASTRPC_CTXID_MASK) >> 4);
>> +	ctxid = ((rsp->ctx & FASTRPC_CTXID_MASK) >> FASTRPC_CTXID_POS);
>>  
>>  	spin_lock_irqsave(&cctx->lock, flags);
>>  	ctx = idr_find(&cctx->ctx_idr, ctxid);
>> -- 
>> 2.34.1
>>

Re: [PATCH v3 3/3] misc: fastrpc: Add polling mode support for fastRPC driver

[Ekansh Gupta]

On 11/19/2025 2:26 PM, Dmitry Baryshkov wrote:
> On Thu, Nov 13, 2025 at 12:11:11PM +0530, Ekansh Gupta wrote:
>> For any remote call to DSP, after sending an invocation message,
>> fastRPC driver waits for glink response and during this time the
>> CPU can go into low power modes. This adds latency to overall fastrpc
>> call as CPU wakeup and scheduling latencies are included. Add polling
>> mode support with which fastRPC driver will poll continuously on a
>> memory after sending a message to remote subsystem which will eliminate
>> CPU wakeup and scheduling latencies and reduce fastRPC overhead. Poll
>> mode can be enabled by user by making a remote_handle64_control request.
> Which request?? I thought it's enabled by making an IOCTL.
Yes, it should be set_options IOCTL, I added user library API details. I'll modify this.
>
>> Signed-off-by: Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>
>> ---
>>  drivers/misc/fastrpc.c      | 138 ++++++++++++++++++++++++++++++++++--
>>  include/uapi/misc/fastrpc.h |   9 +++
>>  2 files changed, 140 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
>> index ccba3b6dfdfa..60de9dcb9815 100644
>> --- a/drivers/misc/fastrpc.c
>> +++ b/drivers/misc/fastrpc.c
>> @@ -22,6 +22,8 @@
>>  #include <linux/firmware/qcom/qcom_scm.h>
>>  #include <uapi/misc/fastrpc.h>
>>  #include <linux/of_reserved_mem.h>
>> +#include <linux/compiler.h>
>> +#include <linux/iopoll.h>
>>  
>>  #define ADSP_DOMAIN_ID (0)
>>  #define MDSP_DOMAIN_ID (1)
>> @@ -37,6 +39,7 @@
>>  #define FASTRPC_CTX_MAX (256)
>>  #define FASTRPC_INIT_HANDLE	1
>>  #define FASTRPC_DSP_UTILITIES_HANDLE	2
>> +#define FASTRPC_MAX_STATIC_HANDLE (20)
>>  #define FASTRPC_CTXID_MASK (0xFF00)
>>  #define FASTRPC_CTXID_POS (8)
>>  #define INIT_FILELEN_MAX (2 * 1024 * 1024)
>> @@ -106,6 +109,12 @@
>>  
>>  #define miscdev_to_fdevice(d) container_of(d, struct fastrpc_device, miscdev)
>>  
>> +/* Poll response number from remote processor for call completion */
>> +#define FASTRPC_POLL_RESPONSE (0xdecaf)
>> +
>> +/* Polling mode timeout limit */
>> +#define FASTRPC_POLL_MAX_TIMEOUT_US (10000)
>> +
>>  struct fastrpc_phy_page {
>>  	u64 addr;		/* physical address */
>>  	u64 size;		/* size of contiguous region */
>> @@ -236,8 +245,14 @@ struct fastrpc_invoke_ctx {
>>  	u32 sc;
>>  	u64 *fdlist;
>>  	u32 *crc;
>> +	/* Poll memory that DSP updates */
>> +	u32 *poll;
>>  	u64 ctxid;
>>  	u64 msg_sz;
>> +	/* work done status flag */
>> +	bool is_work_done;
>> +	/* process updates poll memory instead of glink response */
>> +	bool is_polled;
>>  	struct kref refcount;
>>  	struct list_head node; /* list of ctxs */
>>  	struct completion work;
>> @@ -301,6 +316,8 @@ struct fastrpc_user {
>>  	int client_id;
>>  	int pd;
>>  	bool is_secure_dev;
>> +	/* Flags poll mode state */
>> +	bool poll_mode;
>>  	/* Lock for lists */
>>  	spinlock_t lock;
>>  	/* lock for allocations */
>> @@ -894,7 +911,8 @@ static int fastrpc_get_meta_size(struct fastrpc_invoke_ctx *ctx)
>>  		sizeof(struct fastrpc_invoke_buf) +
>>  		sizeof(struct fastrpc_phy_page)) * ctx->nscalars +
>>  		sizeof(u64) * FASTRPC_MAX_FDLIST +
>> -		sizeof(u32) * FASTRPC_MAX_CRCLIST;
>> +		sizeof(u32) * FASTRPC_MAX_CRCLIST +
>> +		sizeof(u32);
>>  
>>  	return size;
>>  }
>> @@ -990,6 +1008,7 @@ static int fastrpc_get_args(u32 kernel, struct fastrpc_invoke_ctx *ctx)
>>  	list = fastrpc_invoke_buf_start(rpra, ctx->nscalars);
>>  	pages = fastrpc_phy_page_start(list, ctx->nscalars);
>>  	ctx->fdlist = (u64 *)(pages + ctx->nscalars);
>> +	ctx->poll = (u32 *)(ctx->fdlist + FASTRPC_MAX_FDLIST + FASTRPC_MAX_CRCLIST);
>>  	args = (uintptr_t)ctx->buf->virt + metalen;
>>  	rlen = pkt_size - metalen;
>>  	ctx->rpra = rpra;
>> @@ -1158,6 +1177,75 @@ static int fastrpc_invoke_send(struct fastrpc_session_ctx *sctx,
>>  
>>  }
>>  
>> +static inline u32 fastrpc_poll_op(void *p)
>> +{
>> +	struct fastrpc_invoke_ctx *ctx = p;
>> +
>> +	dma_rmb();
>> +	return READ_ONCE(*ctx->poll);
> How does this work with caches? Does it require dma-coherent fastrpc
> devices?
I'm assuming it will work the same way any normal RPC call works on platform with
no cache coherency. Is there any other change/check expected for this?
>
>> +}
>> +
>> +static int poll_for_remote_response(struct fastrpc_invoke_ctx *ctx)
>> +{
>> +	u32 val;
>> +	int ret;
>> +
>> +	/*
>> +	 * Poll until DSP writes FASTRPC_POLL_RESPONSE into *ctx->poll
>> +	 * or until another path marks the work done.
>> +	 */
>> +	ret = read_poll_timeout_atomic(fastrpc_poll_op, val,
>> +				       (val == FASTRPC_POLL_RESPONSE) ||
>> +				       ctx->is_work_done, 1,
>> +				       FASTRPC_POLL_MAX_TIMEOUT_US, false, ctx);
>> +
>> +	if (!ret && val == FASTRPC_POLL_RESPONSE) {
>> +		ctx->is_work_done = true;
>> +		ctx->retval = 0;
>> +	}
>> +
>> +	if (ret == -ETIMEDOUT)
>> +		ret = -EIO;
>> +
>> +	return ret;
>> +}
>> +
>> +static inline int fastrpc_wait_for_response(struct fastrpc_invoke_ctx *ctx,
>> +					    u32 kernel)
>> +{
>> +	int err = 0;
>> +
>> +	if (kernel) {
>> +		if (!wait_for_completion_timeout(&ctx->work, 10 * HZ))
>> +			err = -ETIMEDOUT;
>> +	} else {
>> +		err = wait_for_completion_interruptible(&ctx->work);
>> +	}
>> +
>> +	return err;
>> +}
>> +
>> +static int fastrpc_wait_for_completion(struct fastrpc_invoke_ctx *ctx,
>> +				       u32 kernel)
>> +{
>> +	int err;
>> +
>> +	do {
>> +		if (ctx->is_polled) {
>> +			err = poll_for_remote_response(ctx);
>> +			/* If polling timed out, move to normal response mode */
>> +			if (err)
>> +				ctx->is_polled = false;
>> +		} else {
>> +			err = fastrpc_wait_for_response(ctx, kernel);
>> +			if (err)
>> +				return err;
>> +		}
>> +	} while (!ctx->is_work_done);
>> +
>> +	return err;
>> +}
>> +
>>  static int fastrpc_internal_invoke(struct fastrpc_user *fl,  u32 kernel,
>>  				   u32 handle, u32 sc,
>>  				   struct fastrpc_invoke_args *args)
>> @@ -1193,16 +1281,25 @@ static int fastrpc_internal_invoke(struct fastrpc_user *fl,  u32 kernel,
>>  	if (err)
>>  		goto bail;
>>  
>> -	if (kernel) {
>> -		if (!wait_for_completion_timeout(&ctx->work, 10 * HZ))
>> -			err = -ETIMEDOUT;
>> -	} else {
>> -		err = wait_for_completion_interruptible(&ctx->work);
>> -	}
>> +	/*
>> +	 * Set message context as polled if the call is for a user PD
>> +	 * dynamic module and user has enabled poll mode.
>> +	 */
>> +	if (handle > FASTRPC_MAX_STATIC_HANDLE && fl->pd == USER_PD &&
>> +	    fl->poll_mode)
>> +		ctx->is_polled = true;
>> +
>> +	err = fastrpc_wait_for_completion(ctx, kernel);
>>  
>>  	if (err)
>>  		goto bail;
>>  
>> +	if (!ctx->is_work_done) {
>> +		err = -ETIMEDOUT;
>> +		dev_dbg(fl->sctx->dev, "Invalid workdone state for handle 0x%x, sc 0x%x\n",
>> +			handle, sc);
>> +		goto bail;
>> +	}
>>  	/* make sure that all memory writes by DSP are seen by CPU */
>>  	dma_rmb();
>>  	/* populate all the output buffers with results */
>> @@ -1780,6 +1877,29 @@ static int fastrpc_get_info_from_kernel(struct fastrpc_ioctl_capability *cap,
>>  	return 0;
>>  }
>>  
>> +static int fastrpc_set_option(struct fastrpc_user *fl, char __user *argp)
>> +{
>> +	struct fastrpc_ioctl_set_option opt = {0};
>> +	int i;
>> +
>> +	if (copy_from_user(&opt, argp, sizeof(opt)))
>> +		return -EFAULT;
>> +
>> +	for (i = 0; i < ARRAY_SIZE(opt.reserved); i++) {
>> +		if (opt.reserved[i] != 0)
>> +			return -EINVAL;
>> +	}
> Empty line.
Ack.
>
>> +	if (opt.req != FASTRPC_POLL_MODE)
>> +		return -EINVAL;
>> +
>> +	if (opt.enable)
>> +		fl->poll_mode = true;
>> +	else
>> +		fl->poll_mode = false;
>> +
>> +	return 0;
>> +}
>> +
>>  static int fastrpc_get_dsp_info(struct fastrpc_user *fl, char __user *argp)
>>  {
>>  	struct fastrpc_ioctl_capability cap = {0};
>> @@ -2134,6 +2254,9 @@ static long fastrpc_device_ioctl(struct file *file, unsigned int cmd,
>>  	case FASTRPC_IOCTL_MEM_UNMAP:
>>  		err = fastrpc_req_mem_unmap(fl, argp);
>>  		break;
>> +	case FASTRPC_IOCTL_SET_OPTION:
>> +		err = fastrpc_set_option(fl, argp);
>> +		break;
>>  	case FASTRPC_IOCTL_GET_DSP_INFO:
>>  		err = fastrpc_get_dsp_info(fl, argp);
>>  		break;
>> @@ -2465,6 +2588,7 @@ static int fastrpc_rpmsg_callback(struct rpmsg_device *rpdev, void *data,
>>  
>>  	ctx->retval = rsp->retval;
>>  	complete(&ctx->work);
>> +	ctx->is_work_done = true;
>>  
>>  	/*
>>  	 * The DMA buffer associated with the context cannot be freed in
>> diff --git a/include/uapi/misc/fastrpc.h b/include/uapi/misc/fastrpc.h
>> index c6e2925f47e6..6c1375ba0042 100644
>> --- a/include/uapi/misc/fastrpc.h
>> +++ b/include/uapi/misc/fastrpc.h
>> @@ -16,6 +16,7 @@
>>  #define FASTRPC_IOCTL_INIT_CREATE_STATIC _IOWR('R', 9, struct fastrpc_init_create_static)
>>  #define FASTRPC_IOCTL_MEM_MAP		_IOWR('R', 10, struct fastrpc_mem_map)
>>  #define FASTRPC_IOCTL_MEM_UNMAP		_IOWR('R', 11, struct fastrpc_mem_unmap)
>> +#define FASTRPC_IOCTL_SET_OPTION	_IOWR('R', 12, struct fastrpc_ioctl_set_option)
>>  #define FASTRPC_IOCTL_GET_DSP_INFO	_IOWR('R', 13, struct fastrpc_ioctl_capability)
>>  
>>  /**
>> @@ -66,6 +67,8 @@ enum fastrpc_proc_attr {
>>  
>>  /* Fastrpc attribute for memory protection of buffers */
>>  #define FASTRPC_ATTR_SECUREMAP	(1)
>> +/* Set option request ID to enable poll mode */
>> +#define FASTRPC_POLL_MODE	(1)
>>  
>>  struct fastrpc_invoke_args {
>>  	__u64 ptr;
>> @@ -133,6 +136,12 @@ struct fastrpc_mem_unmap {
>>  	__s32 reserved[5];
>>  };
>>  
>> +struct fastrpc_ioctl_set_option {
>> +	__u32 req;		/* request id */
>> +	__u32 enable;	/* enable flag */
> s/enable/value/ ?
Ack.
>
>> +	__s32 reserved[6];
> I think you got feedback from Greg regarding handling of reserved fields
> few months ago. Please drop them.
I remember the comment asking to add proper checks for reserved bit[1]. I have added the
necessary checks. Please correct me if you are pointing to some other discussion.

[1] https://lore.kernel.org/all/2023092840-rental-ascension-b062@gregkh/
>
>> +};
>> +
>>  struct fastrpc_ioctl_capability {
>>  	__u32 unused; /* deprecated, ignored by the kernel */
>>  	__u32 attribute_id;
>> -- 
>> 2.34.1
>>