Re: [git pull] drm for 6.17-rc1

[Mario Limonciello <superm1@kernel.org>]

On 7/31/25 10:37 AM, Linus Torvalds wrote:
> On Wed, 30 Jul 2025 at 21:58, Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
>>
>> d7b618bc41ee3d44c070212dff93949702ede997 is the first bad commit
>>      drm/amd/display: Refactor DSC cap calculations
>>
>> Let me go see how painful it is to just revert it from top-of-tree.
> 
> So with that reverted (didn't require a lot of fixing, only minor
> unrelated context added nearby later), current top-of-tree works for
> me again.
> 
> The revert I used for testing attached just so people can see exactly
> what I did.
> 
> It's late here, I wasn't getting any more work done today anyway, so
> I'll leave it like this for now.
> 
> I can continue to do the merge window with this revert purely local
> for a while, so if somebody comes up with a proper fix, I can test
> that out.
> 
>              Linus

Pure guess from looking at the diff from 
d7b618bc41ee3d44c070212dff93949702ede997, maybe the NULL ptr is a deref 
on a pointer that doesn't have funcs declared being an older GPU.  So 
maybe check for funcs?

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 a454d16e6586..95d51de26c0b 100644
--- a/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c
+++ b/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c
@@ -673,7 +673,7 @@ static void get_dsc_enc_caps(
                 return;

         /* check if reported cap global or only for a single DCN DSC enc */
-       if (dsc->funcs->dsc_get_enc_caps) {
+       if (dsc->funcs && dsc->funcs->dsc_get_enc_caps) {
                 if (!dsc->ctx->dc->debug.disable_dsc)
                         dsc->funcs->dsc_get_enc_caps(dsc_enc_caps, 
pixel_clock_100Hz);
         } else {