* [PATCH] spi: Fix regression when the SPI controller does not pass max_speed_hz
@ 2020-12-28 19:32 Fabio Estevam
0 siblings, 0 replies; only message in thread
From: Fabio Estevam @ 2020-12-28 19:32 UTC (permalink / raw)
To: broonie; +Cc: tudor.ambarus, linux-spi, Fabio Estevam
Since commit 9326e4f1e5dd ("spi: Limit the spi device max speed to
controller's max speed") the following regression is observed on an
imx6q-sabresd:
[ 3.918284] spi_imx 2008000.spi: cannot set clock freq: 0 (base freq: 60000000)
[ 3.925953] Division by zero in kernel.
[ 3.929831] CPU: 1 PID: 1 Comm: swapper/0 Tainted: G W 5.10.0-next-20201223 #276
[ 3.938565] Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
[ 3.945124] [<c0111a68>] (unwind_backtrace) from [<c010c068>] (show_stack+0x10/0x14)
[ 3.952925] [<c010c068>] (show_stack) from [<c0e11540>] (dump_stack+0xe0/0x10c)
[ 3.960279] [<c0e11540>] (dump_stack) from [<c05d471c>] (Ldiv0+0x8/0x10)
[ 3.967026] [<c05d471c>] (Ldiv0) from [<c089b044>] (mx51_ecspi_prepare_transfer+0xfc/0x17c)
The spi-imx driver does not fill the max_speed_hz field, so we get:
spi->max_speed_hz = 20MHz
spi->controller->max_speed_hz = 0MHz
which will result in spi->max_speed_hz being 0, causing the division by
zero in the spi-imx driver.
Fix this problem, by checking if spi->controller->max_speed_hz is not
zero prior to assign it to spi->max_speed_hz.
Fixes: 9326e4f1e5dd ("spi: Limit the spi device max speed to controller's max speed")
Signed-off-by: Fabio Estevam <festevam@gmail.com>
---
drivers/spi/spi.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 51d7c004fbab..daa3d89484df 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -3379,8 +3379,9 @@ int spi_setup(struct spi_device *spi)
return status;
if (!spi->max_speed_hz ||
- spi->max_speed_hz > spi->controller->max_speed_hz)
- spi->max_speed_hz = spi->controller->max_speed_hz;
+ (spi->max_speed_hz > spi->controller->max_speed_hz))
+ if (spi->controller->max_speed_hz)
+ spi->max_speed_hz = spi->controller->max_speed_hz;
mutex_lock(&spi->controller->io_mutex);
--
2.17.1
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2020-12-28 19:32 [PATCH] spi: Fix regression when the SPI controller does not pass max_speed_hz Fabio Estevam
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