Re: [PATCH v3 2/2] usb: typec: ucsi_glink: Increase buffer size to support UCSI v2

[Heikki Krogerus <heikki.krogerus@linux.intel.com>]

On Wed, Aug 27, 2025 at 01:12:41PM -0700, Anjelique Melendez wrote:
> UCSI v2 specification has increased the MSG_IN and MSG_OUT size from
> 16 bytes to 256 bytes each for the message exchange between OPM and PPM
> This makes the total buffer size increase from 48 bytes to 528 bytes.
> Update the buffer size to support this increase.
> 
> Signed-off-by: Anjelique Melendez <anjelique.melendez@oss.qualcomm.com>
> ---
>  drivers/usb/typec/ucsi/ucsi_glink.c | 85 +++++++++++++++++++++++++----
>  1 file changed, 75 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/usb/typec/ucsi/ucsi_glink.c b/drivers/usb/typec/ucsi/ucsi_glink.c
> index 1f9f0d942c1a..fc12569ec520 100644
> --- a/drivers/usb/typec/ucsi/ucsi_glink.c
> +++ b/drivers/usb/typec/ucsi/ucsi_glink.c
> @@ -16,10 +16,10 @@
>  
>  #define PMIC_GLINK_MAX_PORTS		3
>  
> -#define UCSI_BUF_SIZE                   48
> +#define UCSI_BUF_V1_SIZE		(UCSI_MESSAGE_OUT + (UCSI_MESSAGE_OUT - UCSI_MESSAGE_IN))
> +#define UCSI_BUF_V2_SIZE		(UCSIv2_MESSAGE_OUT + (UCSIv2_MESSAGE_OUT - UCSI_MESSAGE_IN))
>  
>  #define MSG_TYPE_REQ_RESP               1
> -#define UCSI_BUF_SIZE                   48
>  
>  #define UC_NOTIFY_RECEIVER_UCSI         0x0
>  #define UC_UCSI_READ_BUF_REQ            0x11
> @@ -32,13 +32,25 @@ struct ucsi_read_buf_req_msg {
>  
>  struct __packed ucsi_read_buf_resp_msg {
>  	struct pmic_glink_hdr   hdr;
> -	u8                      buf[UCSI_BUF_SIZE];
> +	u8                      buf[UCSI_BUF_V1_SIZE];
> +	u32                     ret_code;
> +};
> +
> +struct __packed ucsi_v2_read_buf_resp_msg {
> +	struct pmic_glink_hdr   hdr;
> +	u8                      buf[UCSI_BUF_V2_SIZE];
>  	u32                     ret_code;
>  };

Couldn't you just make a union inside that original struct
ucsi_read_buf_resp_msg?

>  struct __packed ucsi_write_buf_req_msg {
>  	struct pmic_glink_hdr   hdr;
> -	u8                      buf[UCSI_BUF_SIZE];
> +	u8                      buf[UCSI_BUF_V1_SIZE];
> +	u32                     reserved;
> +};
> +
> +struct __packed ucsi_v2_write_buf_req_msg {
> +	struct pmic_glink_hdr   hdr;
> +	u8                      buf[UCSI_BUF_V2_SIZE];
>  	u32                     reserved;
>  };

Ditto for the ucsi_write_buf_req_msg.

> @@ -72,7 +84,7 @@ struct pmic_glink_ucsi {
>  	bool ucsi_registered;
>  	bool pd_running;
>  
> -	u8 read_buf[UCSI_BUF_SIZE];
> +	u8 read_buf[UCSI_BUF_V2_SIZE];
>  };
>  
>  static int pmic_glink_ucsi_read(struct ucsi *__ucsi, unsigned int offset,
> @@ -131,18 +143,34 @@ static int pmic_glink_ucsi_read_message_in(struct ucsi *ucsi, void *val, size_t
>  static int pmic_glink_ucsi_locked_write(struct pmic_glink_ucsi *ucsi, unsigned int offset,
>  					const void *val, size_t val_len)
>  {
> -	struct ucsi_write_buf_req_msg req = {};
> +	struct ucsi_v2_write_buf_req_msg req = {};
> +	size_t len, max_buf_len;
>  	unsigned long left;
>  	int ret;
>  
>  	req.hdr.owner = PMIC_GLINK_OWNER_USBC;
>  	req.hdr.type = MSG_TYPE_REQ_RESP;
>  	req.hdr.opcode = UC_UCSI_WRITE_BUF_REQ;
> +
> +	if (ucsi->ucsi->version >= UCSI_VERSION_2_0) {
> +		max_buf_len = UCSI_BUF_V2_SIZE;
> +		len = sizeof(req);
> +	} else if (ucsi->ucsi->version) {
> +		max_buf_len = UCSI_BUF_V1_SIZE;
> +		len = sizeof(struct ucsi_write_buf_req_msg);
> +	} else {
> +		dev_err(ucsi->dev, "UCSI version not set\n");
> +		return -EINVAL;
> +	}
> +
> +	if (offset + val_len > max_buf_len)
> +		return -EINVAL;
> +
>  	memcpy(&req.buf[offset], val, val_len);
>  
>  	reinit_completion(&ucsi->write_ack);
>  
> -	ret = pmic_glink_send(ucsi->client, &req, sizeof(req));
> +	ret = pmic_glink_send(ucsi->client, &req, len);
>  	if (ret < 0) {
>  		dev_err(ucsi->dev, "failed to send UCSI write request: %d\n", ret);
>  		return ret;
> @@ -216,12 +244,49 @@ static const struct ucsi_operations pmic_glink_ucsi_ops = {
>  
>  static void pmic_glink_ucsi_read_ack(struct pmic_glink_ucsi *ucsi, const void *data, int len)
>  {
> -	const struct ucsi_read_buf_resp_msg *resp = data;
> +	u32 ret_code, buf_len, max_len;
> +	u8 *buf;
> +
> +	if (ucsi->ucsi->version) {
> +		if (ucsi->ucsi->version >= UCSI_VERSION_2_0) {
> +			max_len = sizeof(struct ucsi_v2_read_buf_resp_msg);
> +			buf = ((struct ucsi_v2_read_buf_resp_msg *)data)->buf;
> +			buf_len = UCSI_BUF_V2_SIZE;
> +		} else {
> +			max_len = sizeof(struct ucsi_read_buf_resp_msg);
> +			buf = ((struct ucsi_read_buf_resp_msg *)data)->buf;
> +			buf_len = UCSI_BUF_V1_SIZE;
> +		}
> +	} else if (!ucsi->ucsi->version && !ucsi->ucsi_registered) {

ucsi->ucsi->version will never be set in this else condition,
so no need to check it, no?

> +		/*
> +		 * If UCSI version is not known yet because device is not registered, choose buffer
> +		 * size which best fits incoming data
> +		 */
> +		if (len > sizeof(struct pmic_glink_hdr) + UCSI_BUF_V2_SIZE) {
> +			max_len = sizeof(struct ucsi_v2_read_buf_resp_msg);
> +			buf = ((struct ucsi_v2_read_buf_resp_msg *)data)->buf;
> +			buf_len = UCSI_BUF_V2_SIZE;
> +		} else {
> +			max_len = sizeof(struct ucsi_read_buf_resp_msg);
> +			buf = ((struct ucsi_read_buf_resp_msg *)data)->buf;
> +			buf_len = UCSI_BUF_V1_SIZE;
> +		}
> +	} else {
> +		dev_err(ucsi->dev, "UCSI version not set\n");
> +		return;
> +	}

I don't really see when you could enter that else statement?

> -	if (resp->ret_code)
> +	if (len > max_len)
> +		return;
> +
> +	if (buf_len > len - sizeof(struct pmic_glink_hdr) - sizeof(u32))
> +		buf_len = len - sizeof(struct pmic_glink_hdr) - sizeof(u32);
> +
> +	memcpy(&ret_code, buf + sizeof(struct pmic_glink_hdr) + buf_len, sizeof(u32));
> +	if (ret_code)
>  		return;
>  
> -	memcpy(ucsi->read_buf, resp->buf, UCSI_BUF_SIZE);
> +	memcpy(ucsi->read_buf, buf, buf_len);
>  	complete(&ucsi->read_ack);
>  }

thanks,

-- 
heikki