Re: [PATCH v3 06/13] media: ti: j721e-csi2rx: get number of contexts from device tree

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Rishikesh,

Thank you for the patch.

On Thu, Apr 17, 2025 at 12:25:47PM +0530, Rishikesh Donadkar wrote:
> From: Pratyush Yadav <p.yadav@ti.com>
> 
> Different platforms that use this driver might have different number of
> DMA channels allocated for CSI. So only as many DMA contexts can be used
> as the number of DMA channels available. Get the number of channels
> provided via device tree and only configure that many contexts, and
> hence only that many pads.
> 
> Signed-off-by: Pratyush Yadav <p.yadav@ti.com>
> Co-developed-by: Jai Luthra <j-luthra@ti.com>
> Signed-off-by: Jai Luthra <j-luthra@ti.com>
> Signed-off-by: Rishikesh Donadkar <r-donadkar@ti.com>
> ---
>  .../platform/ti/j721e-csi2rx/j721e-csi2rx.c   | 41 ++++++++++++++-----
>  1 file changed, 30 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
> index ea7e331e872af..e85d04d7c2ff9 100644
> --- a/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
> +++ b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
> @@ -40,7 +40,7 @@
>  #define SHIM_PSI_CFG0_DST_TAG		GENMASK(31, 16)
>  
>  #define PSIL_WORD_SIZE_BYTES		16
> -#define TI_CSI2RX_NUM_CTX		1
> +#define TI_CSI2RX_MAX_CTX		32
>  
>  /*
>   * There are no hard limits on the width or height. The DMA engine can handle
> @@ -53,8 +53,8 @@
>  
>  #define TI_CSI2RX_PAD_SINK		0
>  #define TI_CSI2RX_PAD_FIRST_SOURCE	1
> -#define TI_CSI2RX_NUM_SOURCE_PADS	1
> -#define TI_CSI2RX_NUM_PADS		(1 + TI_CSI2RX_NUM_SOURCE_PADS)
> +#define TI_CSI2RX_MAX_SOURCE_PADS	TI_CSI2RX_MAX_CTX
> +#define TI_CSI2RX_MAX_PADS		(1 + TI_CSI2RX_MAX_SOURCE_PADS)
>  
>  #define DRAIN_TIMEOUT_MS		50
>  #define DRAIN_BUFFER_SIZE		SZ_32K
> @@ -112,14 +112,15 @@ struct ti_csi2rx_dev {
>  	void __iomem			*shim;
>  	struct mutex			mutex; /* To serialize ioctls. */
>  	unsigned int			enable_count;
> +	unsigned int			num_ctx;
>  	struct v4l2_device		v4l2_dev;
>  	struct media_device		mdev;
>  	struct media_pipeline		pipe;
> -	struct media_pad		pads[TI_CSI2RX_NUM_PADS];
> +	struct media_pad		pads[TI_CSI2RX_MAX_PADS];
>  	struct v4l2_async_notifier	notifier;
>  	struct v4l2_subdev		*source;
>  	struct v4l2_subdev		subdev;
> -	struct ti_csi2rx_ctx		ctx[TI_CSI2RX_NUM_CTX];
> +	struct ti_csi2rx_ctx		ctx[TI_CSI2RX_MAX_CTX];
>  	/* Buffer to drain stale data from PSI-L endpoint */
>  	struct {
>  		void			*vaddr;
> @@ -449,7 +450,7 @@ static int csi_async_notifier_complete(struct v4l2_async_notifier *notifier)
>  		return ret;
>  
>  	/* Create and link video nodes for all DMA contexts */
> -	for (i = 0; i < TI_CSI2RX_NUM_CTX; i++) {
> +	for (i = 0; i < csi->num_ctx; i++) {
>  		struct ti_csi2rx_ctx *ctx = &csi->ctx[i];
>  		struct video_device *vdev = &ctx->vdev;
>  
> @@ -1212,10 +1213,11 @@ static int ti_csi2rx_v4l2_init(struct ti_csi2rx_dev *csi)
>  	csi->pads[TI_CSI2RX_PAD_SINK].flags = MEDIA_PAD_FL_SINK;
>  
>  	for (unsigned int i = TI_CSI2RX_PAD_FIRST_SOURCE;
> -	     i < TI_CSI2RX_NUM_PADS; i++)
> +	     i < TI_CSI2RX_PAD_FIRST_SOURCE + csi->num_ctx; i++)
>  		csi->pads[i].flags = MEDIA_PAD_FL_SOURCE;
>  
> -	ret = media_entity_pads_init(&sd->entity, ARRAY_SIZE(csi->pads),
> +	ret = media_entity_pads_init(&sd->entity,
> +				     TI_CSI2RX_PAD_FIRST_SOURCE + csi->num_ctx,
>  				     csi->pads);
>  	if (ret)
>  		goto unregister_media;
> @@ -1301,8 +1303,9 @@ static int ti_csi2rx_init_ctx(struct ti_csi2rx_ctx *ctx)
>  
>  static int ti_csi2rx_probe(struct platform_device *pdev)
>  {
> +	struct device_node *np = pdev->dev.of_node;
>  	struct ti_csi2rx_dev *csi;
> -	int ret, i;
> +	int ret, i, count;
>  
>  	csi = devm_kzalloc(&pdev->dev, sizeof(*csi), GFP_KERNEL);
>  	if (!csi)
> @@ -1324,13 +1327,29 @@ static int ti_csi2rx_probe(struct platform_device *pdev)
>  	if (!csi->drain.vaddr)
>  		return -ENOMEM;
>  
> +	/* Only use as many contexts as the number of DMA channels allocated. */
> +	count = of_property_count_strings(np, "dma-names");
> +	if (count < 0) {
> +		dev_err(csi->dev, "Failed to get DMA channel count: %d\n",
> +			count);
> +		return count;

You're leaking the drain buffer.

> +	}
> +
> +	csi->num_ctx = count;
> +	if (csi->num_ctx > TI_CSI2RX_MAX_CTX) {
> +		dev_warn(csi->dev,
> +			 "%u DMA channels passed. Maximum is %u. Ignoring the rest.\n",
> +			 csi->num_ctx, TI_CSI2RX_MAX_CTX);

I'd rather turn this into a hard error and get the device trees fixed.

> +		csi->num_ctx = TI_CSI2RX_MAX_CTX;
> +	}
> +
>  	mutex_init(&csi->mutex);
>  
>  	ret = ti_csi2rx_v4l2_init(csi);
>  	if (ret)
>  		goto err_v4l2;
>  
> -	for (i = 0; i < TI_CSI2RX_NUM_CTX; i++) {
> +	for (i = 0; i < csi->num_ctx; i++) {
>  		csi->ctx[i].idx = i;
>  		csi->ctx[i].csi = csi;
>  		ret = ti_csi2rx_init_ctx(&csi->ctx[i]);
> @@ -1369,7 +1388,7 @@ static void ti_csi2rx_remove(struct platform_device *pdev)
>  	struct ti_csi2rx_dev *csi = platform_get_drvdata(pdev);
>  	unsigned int i;
>  
> -	for (i = 0; i < TI_CSI2RX_NUM_CTX; i++)
> +	for (i = 0; i < csi->num_ctx; i++)
>  		ti_csi2rx_cleanup_ctx(&csi->ctx[i]);
>  
>  	ti_csi2rx_cleanup_notifier(csi);

-- 
Regards,

Laurent Pinchart