[PATCH] drm/amd/pm: Prevent divide by zero

[Alex Deucher]

Applied.  Thanks!

On Mon, Jul 11, 2022 at 9:06 PM Mr. B34r <mr.b34r at kolabnow.com> wrote:
>
>  From: Yefim Barashkin <mr.b34r at kolabnow.com>
>
> divide error: 0000 [#1] SMP PTI
> CPU: 3 PID: 78925 Comm: tee Not tainted 5.15.50-1-lts #1
> Hardware name: MSI MS-7A59/Z270 SLI PLUS (MS-7A59), BIOS 1.90 01/30/2018
> RIP: 0010:smu_v11_0_set_fan_speed_rpm+0x11/0x110 [amdgpu]
>
> Speed is user-configurable through a file.
> I accidentally set it to zero, and the driver crashed.
>
> Signed-off-by: Yefim Barashkin <mr.b34r at kolabnow.com>
> ---
>   drivers/gpu/drm/amd/pm/swsmu/smu11/smu_v11_0.c | 4 ++++
>   1 file changed, 4 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/pm/swsmu/smu11/smu_v11_0.c
> b/drivers/gpu/drm/amd/pm/swsmu/smu11/smu_v11_0.c
> index 5f8809f6990d..69cebdb58c04 100644
> --- a/drivers/gpu/drm/amd/pm/swsmu/smu11/smu_v11_0.c
> +++ b/drivers/gpu/drm/amd/pm/swsmu/smu11/smu_v11_0.c
> @@ -1236,6 +1236,10 @@ int smu_v11_0_set_fan_speed_rpm(struct
> smu_context *smu,
>       * - For some Sienna Cichlid SKU, the fan speed cannot be set
>       *   lower than 500 RPM.
>       */
> +
> +   if (speed == 0)
> +       return -EINVAL;
> +
>      tach_period = 60 * crystal_clock_freq * 10000 / (8 * speed);
>      WREG32_SOC15(THM, 0, mmCG_TACH_CTRL,
>               REG_SET_FIELD(RREG32_SOC15(THM, 0, mmCG_TACH_CTRL),
> --
> 2.36.1