soundwire: cadence: Don't overflow the command FIFOs

The command FIFOs in the Cadence IP can be configured during design
up to 32 entries, and the code in cadence_master.c was assuming the
full 32-entry FIFO. But all current Intel implementations use an 8-entry
FIFO.

Up to now the longest message used was 6 entries so this wasn't
causing any problem. But future Cirrus Logic codecs have downloadable
firmware or tuning blobs. It is more efficient for the codec driver to
issue long transfers that can take advantage of any queuing in the
Soundwire controller and avoid the overhead of repeatedly writing the
page registers.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Fixes: 2f52a5177caa ("soundwire: cdns: Add cadence library")
Link: https://lore.kernel.org/r/20221202161812.4186897-2-rf@opensource.cirrus.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

diff --git a/drivers/soundwire/cadence_master.c b/drivers/soundwire/cadence_master.c
index a1de363..27699f3 100644 (file)
--- a/drivers/soundwire/cadence_master.c
+++ b/drivers/soundwire/cadence_master.c
@@ -127,7 +127,8 @@ MODULE_PARM_DESC(cdns_mcp_int_mask, "Cadence MCP IntMask");
 
 #define CDNS_MCP_CMD_BASE                      0x80
 #define CDNS_MCP_RESP_BASE                     0x80
-#define CDNS_MCP_CMD_LEN                       0x20
+/* FIFO can hold 8 commands */
+#define CDNS_MCP_CMD_LEN                       8
 #define CDNS_MCP_CMD_WORD_LEN                  0x4
 
 #define CDNS_MCP_CMD_SSP_TAG                   BIT(31)