It was <2020-08-19 śro 14:49>, when Krzysztof Kozlowski wrote:

On Wed, Aug 19, 2020 at 02:32:07PM +0200, Łukasz Stelmach wrote:

quoted

Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com>

Why? Everything works fine and suddenly minimum timeout is 100 ms?

Actually I am not 100% sure the max() call is required, maybe +30 is
enough. Definitely some minimum value is required because for small
tranfers (100s of bytes) ms is 0 after the first assignment.

quoted

---
 drivers/spi/spi-s3c64xx.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
index 27d77600a820..27db1e0f6f32 100644
--- a/drivers/spi/spi-s3c64xx.c
+++ b/drivers/spi/spi-s3c64xx.c

@@ -464,7 +464,8 @@ static int s3c64xx_wait_for_dma(struct s3c64xx_spi_driver_data *sdd,
 
 	/* millisecs to xfer 'len' bytes @ 'cur_speed' */
 	ms = xfer->len * 8 * 1000 / sdd->cur_speed;
-	ms += 10; /* some tolerance */
+	ms = (ms * 10) + 30;    /* some tolerance */
+	ms = max(ms, 100);      /* minimum timeout */
 
 	val = msecs_to_jiffies(ms) + 10;
 	val = wait_for_completion_timeout(&sdd->xfer_completion, val);

-- 
2.26.2

-- 
Łukasz Stelmach
Samsung R&D Institute Poland
Samsung Electronics