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 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
