[PATCH 04/14] fsi: master-gpio: Rename and adjust send delay

From: Benjamin Herrenschmidt
Date: Tue Jun 26 2018 - 19:49:14 EST


What the driver called "FSI_GPIO_PRIME_SLAVE_CLOCKS" is what
the FSI spec calls tSendDelay and should be 16 clocks by
default.

Signed-off-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
---
drivers/fsi/fsi-master-gpio.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/fsi/fsi-master-gpio.c b/drivers/fsi/fsi-master-gpio.c
index 1fd8b417939d..836587701ceb 100644
--- a/drivers/fsi/fsi-master-gpio.c
+++ b/drivers/fsi/fsi-master-gpio.c
@@ -18,6 +18,7 @@

#define FSI_GPIO_STD_DLY 1 /* Standard pin delay in nS */
#define FSI_ECHO_DELAY_CLOCKS 16 /* Number clocks for echo delay */
+#define FSI_SEND_DELAY_CLOCKS 16 /* Number clocks for send delay */
#define FSI_PRE_BREAK_CLOCKS 50 /* Number clocks to prep for break */
#define FSI_BREAK_CLOCKS 256 /* Number of clocks to issue break */
#define FSI_POST_BREAK_CLOCKS 16000 /* Number clocks to set up cfam */
@@ -48,7 +49,6 @@
#define FSI_GPIO_CRC_SIZE 4
#define FSI_GPIO_MSG_ID_SIZE 2
#define FSI_GPIO_MSG_RESPID_SIZE 2
-#define FSI_GPIO_PRIME_SLAVE_CLOCKS 20

#define LAST_ADDR_INVALID 0x1

@@ -535,9 +535,12 @@ static int poll_for_response(struct fsi_master_gpio *master,
if (busy_count > 0)
trace_fsi_master_gpio_poll_response_busy(master, busy_count);
fail:
- /* Clock the slave enough to be ready for next operation */
+ /*
+ * tSendDelay clocks, avoids signal reflections when switching
+ * from receive of response back to send of data.
+ */
local_irq_save(flags);
- clock_zeros(master, FSI_GPIO_PRIME_SLAVE_CLOCKS);
+ clock_zeros(master, FSI_SEND_DELAY_CLOCKS);
local_irq_restore(flags);

return rc;
--
2.17.1