From: Richard Fitzgerald rf@opensource.cirrus.com

[ Upstream commit ba05b39d265bdd16913f7684600d9d41e2796745 ]

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 Link: https://lore.kernel.org/r/20220916103505.1562210-1-rf@opensource.cirrus.com Signed-off-by: Vinod Koul vkoul@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 c6d421a4b91b..a3247692ddc0 100644 --- a/drivers/soundwire/cadence_master.c +++ b/drivers/soundwire/cadence_master.c @@ -501,9 +501,12 @@ 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; }