spi: fix the divide by 0 error when calculating xfer waiting time

[ Upstream commit 6170d077bf92c5b3dfbe1021688d3c0404f7c9e9 ]

The xfer waiting time is the result of xfer->len / xfer->speed_hz. This
patch makes the assumption of 100khz xfer speed if the xfer->speed_hz is
not assigned and stays 0. This avoids the divide by 0 issue and ensures
a reasonable tolerant waiting time.

Signed-off-by: Xu Yilun <yilun.xu@intel.com>
Link: https://lore.kernel.org/r/1609723749-3557-1-git-send-email-yilun.xu@intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 2eaa7dbb7010892d32016467c989d063533f1a8f..7694e1ae5b0b2f2d288abeb93eabac136693fb72 100644 (file)
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1100,6 +1100,7 @@ static int spi_transfer_wait(struct spi_controller *ctlr,
 {
        struct spi_statistics *statm = &ctlr->statistics;
        struct spi_statistics *stats = &msg->spi->statistics;
+       u32 speed_hz = xfer->speed_hz;
        unsigned long long ms;
 
        if (spi_controller_is_slave(ctlr)) {
@@ -1108,8 +1109,11 @@ static int spi_transfer_wait(struct spi_controller *ctlr,
                        return -EINTR;
                }
        } else {
+               if (!speed_hz)
+                       speed_hz = 100000;
+
                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)