When slice_height is 0, the division by slice_height in the calculation
of the number of slices will cause a division by zero driver crash. This
leaves the kernel in a state that requires a reboot. This patch adds a
check to avoid the division by zero.
The stack trace below is for the 6.8.4 Kernel. I reproduced the issue on
a Z16 Gen 2 Lenovo Thinkpad with a Apple Studio Display monitor
connected via Thunderbolt. The amdgpu driver crashed with this exception
when I rebooted the system with the monitor connected.
kernel: ? die (arch/x86/kernel/dumpstack.c:421 arch/x86/kernel/dumpstack.c:434 arch/x86/kernel/dumpstack.c:447)
kernel: ? do_trap (arch/x86/kernel/traps.c:113 arch/x86/kernel/traps.c:154)
kernel: ? setup_dsc_config (drivers/gpu/drm/amd/amdgpu/../display/dc/dsc/dc_dsc.c:1053) amdgpu
kernel: ? do_error_trap (./arch/x86/include/asm/traps.h:58 arch/x86/kernel/traps.c:175)
kernel: ? setup_dsc_config (drivers/gpu/drm/amd/amdgpu/../display/dc/dsc/dc_dsc.c:1053) amdgpu
kernel: ? exc_divide_error (arch/x86/kernel/traps.c:194 (discriminator 2))
kernel: ? setup_dsc_config (drivers/gpu/drm/amd/amdgpu/../display/dc/dsc/dc_dsc.c:1053) amdgpu
kernel: ? asm_exc_divide_error (./arch/x86/include/asm/idtentry.h:548)
kernel: ? setup_dsc_config (drivers/gpu/drm/amd/amdgpu/../display/dc/dsc/dc_dsc.c:1053) amdgpu
kernel: dc_dsc_compute_config (drivers/gpu/drm/amd/amdgpu/../display/dc/dsc/dc_dsc.c:1109) amdgpu
After applying this patch, the driver no longer crashes when the monitor
is connected and the system is rebooted. I believe this is the same
issue reported for 3113.
Signed-off-by: Jose Fernandez <[email protected]>
Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/3113
---
drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c b/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c
index ac41f9c0a283..597d5425d6cb 100644
--- a/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c
+++ b/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c
@@ -1055,7 +1055,12 @@ static bool setup_dsc_config(
if (!is_dsc_possible)
goto done;
- dsc_cfg->num_slices_v = pic_height/slice_height;
+ if (slice_height > 0)
+ dsc_cfg->num_slices_v = pic_height/slice_height;
+ else {
+ is_dsc_possible = false;
+ goto done;
+ }
if (target_bandwidth_kbps > 0) {
is_dsc_possible = decide_dsc_target_bpp_x16(
--
2.44.0
…
> +++ b/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c
> @@ -1055,7 +1055,12 @@ static bool setup_dsc_config(
> if (!is_dsc_possible)
> goto done;
>
> - dsc_cfg->num_slices_v = pic_height/slice_height;
> + if (slice_height > 0)
> + dsc_cfg->num_slices_v = pic_height/slice_height;
> + else {
> + is_dsc_possible = false;
> + goto done;
> + }
>
> if (target_bandwidth_kbps > 0) {
> is_dsc_possible = decide_dsc_target_bpp_x16(
I suggest to take another coding style concern into account.
Please use curly brackets for both if branches.
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/coding-style.rst?h=v6.9-rc5#n213
Regards,
Markus