| Message ID | 20201229040450.10052-1-festevam@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] spi: Fix regression when the SPI controller does not pass max_speed_hz | expand |
Hi Fabio, On Tue, Dec 29, 2020 at 5:06 AM Fabio Estevam <festevam@gmail.com> wrote: > 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> See also https://lore.kernel.org/linux-spi/20201216092321.413262-1-tudor.ambarus@microchip.com/ Gr{oetje,eeting}s, Geert
On Tue, Dec 29, 2020 at 09:05:45AM +0100, Geert Uytterhoeven wrote: > See also > https://lore.kernel.org/linux-spi/20201216092321.413262-1-tudor.ambarus@microchip.com/ Right, I already queued that version.
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 51d7c004fbab..e786a94960d5 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -3380,7 +3380,8 @@ int spi_setup(struct spi_device *spi) if (!spi->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);
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> --- Changes since v1: - Do not add unneeded parenthesis. drivers/spi/spi.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)