The xfer waiting time is the result of xfer->len / xfer->speed_hz, but
when the following patch is merged,
commit 9326e4f1e5dd ("spi: Limit the spi device max speed to controller's max
speed")
the xfer->speed_hz may always be clamped to 0 if the controller doesn't
provide its max_speed_hz. There may be no hardware indication of the
max_speed_hz so the controller driver leaves it, but exception happens
when it tries to do irq mode transfer.
This patch makes the assumption of 1khz xfer speed if the xfer->speed_hz
is not assigned. This avoids the divide by 0 issue and ensures a
reasonable tolerant waiting time.
Signed-off-by: Xu Yilun <yilun...@intel.com>
---
drivers/spi/spi.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 51d7c00..2f3c2c9 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1109,6 +1109,7 @@ static int spi_transfer_wait(struct spi_controller *ctlr,
struct spi_statistics *statm = &ctlr->statistics;
struct spi_statistics *stats = &msg->spi->statistics;
unsigned long long ms;
+ u32 speed_hz;
if (spi_controller_is_slave(ctlr)) {
if (wait_for_completion_interruptible(&ctlr->xfer_completion)) {
@@ -1116,8 +1117,9 @@ static int spi_transfer_wait(struct spi_controller *ctlr,
return -EINTR;
}
} else {
+ speed_hz = xfer->speed_hz ? : 1000;
ms = 8LL * 1000LL * xfer->len;
- do_div(ms, xfer->speed_hz);
+ do_div(ms, speed_hz);
ms += ms + 200; /* some tolerance */
if (ms > UINT_MAX)
--
2.7.4
