[PATCH 07/15] fsi/fsi-master-gpio: Reduce dpoll clocks

From: Benjamin Herrenschmidt
Date: Mon May 28 2018 - 21:48:46 EST


FSI_GPIO_DPOLL_CLOCKS is the number of clocks before sending
a DPOLL command after receiving a BUSY status. It should be
at least tSendDelay (16 clocks).

According to comments in the code, it needs to also be at least
21 clocks due to HW issues.

It's currently 100 clocks which impacts performances negatively
in some cases. Reduces it in half to 50 clocks which seems to
still be solid.

Signed-off-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Christopher Bostic <cbostic@xxxxxxxxxxxxxxxxxx>
---
drivers/fsi/fsi-master-gpio.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/fsi/fsi-master-gpio.c b/drivers/fsi/fsi-master-gpio.c
index 029b0a5b6d89..bd2b2cbd5eb5 100644
--- a/drivers/fsi/fsi-master-gpio.c
+++ b/drivers/fsi/fsi-master-gpio.c
@@ -29,7 +29,8 @@
#define FSI_GPIO_CMD_TERM 0x3f
#define FSI_GPIO_CMD_ABS_AR 0x4

-#define FSI_GPIO_DPOLL_CLOCKS 100 /* < 21 will cause slave to hang */
+
+#define FSI_GPIO_DPOLL_CLOCKS 50 /* < 21 will cause slave to hang */

/* Bus errors */
#define FSI_GPIO_ERR_BUSY 1 /* Slave stuck in busy state */
@@ -43,7 +44,7 @@
#define FSI_GPIO_RESP_ACK 0
#define FSI_GPIO_RESP_ACKD 4

-#define FSI_GPIO_MAX_BUSY 100
+#define FSI_GPIO_MAX_BUSY 200
#define FSI_GPIO_MTOE_COUNT 1000
#define FSI_GPIO_DRAIN_BITS 20
#define FSI_GPIO_CRC_SIZE 4
--
2.17.0