The buf passed in struct sdw_msg must only be written for a READ,
in that case the RDATA part of the response is the data value of the
register.

For a write command there is no RDATA, and buf should be assumed to
be const and unmodifable. The original caller should not expect its data
buffer to be corrupted by an sdw_nwrite().

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
---
 drivers/soundwire/cadence_master.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/soundwire/cadence_master.c b/drivers/soundwire/cadence_master.c
index be9cd47f31ec..3ef472049980 100644
--- a/drivers/soundwire/cadence_master.c
+++ b/drivers/soundwire/cadence_master.c
@@ -544,9 +544,12 @@ cdns_fill_msg_resp(struct sdw_cdns *cdns,
 		return SDW_CMD_IGNORED;
 	}
 
-	/* fill response */
-	for (i = 0; i < count; i++)
-		msg->buf[i + offset] = FIELD_GET(CDNS_MCP_RESP_RDATA, cdns->response_buf[i]);
+	if (msg->flags == SDW_MSG_FLAG_READ) {
+		/* fill response */
+		for (i = 0; i < count; i++)
+			msg->buf[i + offset] = FIELD_GET(CDNS_MCP_RESP_RDATA,
+							 cdns->response_buf[i]);
+	}
 
 	return SDW_CMD_OK;
 }
-- 
2.30.2

On 16-09-22, 11:35, Richard Fitzgerald wrote:
> The buf passed in struct sdw_msg must only be written for a READ,
> in that case the RDATA part of the response is the data value of the
> register.
> 
> For a write command there is no RDATA, and buf should be assumed to
> be const and unmodifable. The original caller should not expect its data
> buffer to be corrupted by an sdw_nwrite().

Applied, thanks

-- 
~Vinod

On 9/16/22 12:35, Richard Fitzgerald wrote:
> The buf passed in struct sdw_msg must only be written for a READ,
> in that case the RDATA part of the response is the data value of the
> register.
> 
> For a write command there is no RDATA, and buf should be assumed to
> be const and unmodifable. The original caller should not expect its data
> buffer to be corrupted by an sdw_nwrite().
> 
> Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>

Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>

> ---
>  drivers/soundwire/cadence_master.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/soundwire/cadence_master.c b/drivers/soundwire/cadence_master.c
> index be9cd47f31ec..3ef472049980 100644
> --- a/drivers/soundwire/cadence_master.c
> +++ b/drivers/soundwire/cadence_master.c
> @@ -544,9 +544,12 @@ cdns_fill_msg_resp(struct sdw_cdns *cdns,
>  		return SDW_CMD_IGNORED;
>  	}
>  
> -	/* fill response */
> -	for (i = 0; i < count; i++)
> -		msg->buf[i + offset] = FIELD_GET(CDNS_MCP_RESP_RDATA, cdns->response_buf[i]);
> +	if (msg->flags == SDW_MSG_FLAG_READ) {
> +		/* fill response */
> +		for (i = 0; i < count; i++)
> +			msg->buf[i + offset] = FIELD_GET(CDNS_MCP_RESP_RDATA,
> +							 cdns->response_buf[i]);
> +	}
>  
>  	return SDW_CMD_OK;
>  }