Hi all,

Today's linux-next merge of the drm tree got a conflict in:

  drivers/gpu/drm/amd/display/dc/hwss/dcn35/dcn35_hwseq.c

between commit:

  e835d5144f5e ("drm/amd/display: Avoid race between dcn35_set_drr() and dc_state_destruct()")

from Linus' tree and commit:

  be7a6a517164 ("drm/amd/display: Check stream pointer is initialized before accessing")

from the drm tree.

I fixed it up (see below) and can carry the fix as necessary. This
is now fixed as far as linux-next is concerned, but any non trivial
conflicts should be mentioned to your upstream maintainer when your tree
is submitted for merging.  You may also want to consider cooperating
with the maintainer of the conflicting tree to minimise any particularly
complex conflicts.

-- 
Cheers,
Stephen Rothwell

diff --cc drivers/gpu/drm/amd/display/dc/hwss/dcn35/dcn35_hwseq.c
index d5e9aec52a05,a4c6decee0f8..000000000000
--- a/drivers/gpu/drm/amd/display/dc/hwss/dcn35/dcn35_hwseq.c
+++ b/drivers/gpu/drm/amd/display/dc/hwss/dcn35/dcn35_hwseq.c
@@@ -1462,17 -1414,10 +1414,17 @@@ void dcn35_set_drr(struct pipe_ctx **pi
  	params.vertical_total_mid_frame_num = adjust.v_total_mid_frame_num;
  
  	for (i = 0; i < num_pipes; i++) {
 -		if ((pipe_ctx[i]->stream_res.tg != NULL) && pipe_ctx[i]->stream_res.tg->funcs) {
 +		/* dc_state_destruct() might null the stream resources, so fetch tg
 +		 * here first to avoid a race condition. The lifetime of the pointee
 +		 * itself (the timing_generator object) is not a problem here.
 +		 */
 +		struct timing_generator *tg = pipe_ctx[i]->stream_res.tg;
 +
 +		if ((tg != NULL) && tg->funcs) {
- 			struct dc_crtc_timing *timing = &pipe_ctx[i]->stream->timing;
- 			struct dc *dc = pipe_ctx[i]->stream->ctx->dc;
 +
- 			if (dc->debug.static_screen_wait_frames) {
+ 			if (pipe_ctx[i]->stream && pipe_ctx[i]->stream->ctx->dc->debug.static_screen_wait_frames) {
+ 				struct dc_crtc_timing *timing = &pipe_ctx[i]->stream->timing;
+ 				struct dc *dc = pipe_ctx[i]->stream->ctx->dc;
  				unsigned int frame_rate = timing->pix_clk_100hz / (timing->h_total * timing->v_total);
  
  				if (frame_rate >= 120 && dc->caps.ips_support &&

On 9/16/24 06:15, Stephen Rothwell wrote:

> Hi all,
>
> Today's linux-next merge of the drm tree got a conflict in:
>
>    drivers/gpu/drm/amd/display/dc/hwss/dcn35/dcn35_hwseq.c
>
> between commit:
>
>    e835d5144f5e ("drm/amd/display: Avoid race between dcn35_set_drr() and dc_state_destruct()")
>
> from Linus' tree and commit:
>
>    be7a6a517164 ("drm/amd/display: Check stream pointer is initialized before accessing")
>
> from the drm tree.
>
> I fixed it up (see below) and can carry the fix as necessary. This
> is now fixed as far as linux-next is concerned, but any non trivial
> conflicts should be mentioned to your upstream maintainer when your tree
> is submitted for merging.  You may also want to consider cooperating
> with the maintainer of the conflicting tree to minimise any particularly
> complex conflicts.
>
On close inspection it might be worthwhile to take the same precautions 
that we now take with tg, also with pipe_ctx[i]->stream.

@Alex: What do you think?

With best wishes,
Tobias

+ Harry

On Mon, Sep 16, 2024 at 8:58 AM Tobias Jakobi
<tjakobi@math.uni-bielefeld.de> wrote:
>
> On 9/16/24 06:15, Stephen Rothwell wrote:
>
> > Hi all,
> >
> > Today's linux-next merge of the drm tree got a conflict in:
> >
> >    drivers/gpu/drm/amd/display/dc/hwss/dcn35/dcn35_hwseq.c
> >
> > between commit:
> >
> >    e835d5144f5e ("drm/amd/display: Avoid race between dcn35_set_drr() and dc_state_destruct()")
> >
> > from Linus' tree and commit:
> >
> >    be7a6a517164 ("drm/amd/display: Check stream pointer is initialized before accessing")
> >
> > from the drm tree.
> >
> > I fixed it up (see below) and can carry the fix as necessary. This
> > is now fixed as far as linux-next is concerned, but any non trivial
> > conflicts should be mentioned to your upstream maintainer when your tree
> > is submitted for merging.  You may also want to consider cooperating
> > with the maintainer of the conflicting tree to minimise any particularly
> > complex conflicts.
> >
> On close inspection it might be worthwhile to take the same precautions
> that we now take with tg, also with pipe_ctx[i]->stream.
>
> @Alex: What do you think?

@Wentland, Harry can stream be NULL here?

Alex

>
> With best wishes,
> Tobias
>