[PATCH 0/2] drm/amd: fix VRR race condition during IRQ handling

[Christopher Snowhill]

On Mon Sep 2, 2024 at 2:40 AM PDT, tjakobi wrote:
> From: Tobias Jakobi <tjakobi at math.uni-bielefeld.de>
>
> Hello,
>
> this fixes a nasty race condition in the set_drr() callbacks for DCN10
> and DCN35 that has existed now since quite some time, see this GitLab
> issue for reference.
>
> https://gitlab.freedesktop.org/drm/amd/-/issues/3142
>
> The report just focuses von DCN10, but the same problem also exists in
> the DCN35 code.

Does the problem not exist in the following references to funcs->set_drr?

drivers/gpu/drm/amd/display/dc/hwss/dce110/dce110_hwseq.c:      if (pipe_ctx->stream_res.tg->funcs->set_drr)
drivers/gpu/drm/amd/display/dc/hwss/dce110/dce110_hwseq.c:              pipe_ctx->stream_res.tg->funcs->set_drr(
drivers/gpu/drm/amd/display/dc/hwss/dce110/dce110_hwseq.c:              pipe_ctx[i]->stream_res.tg->funcs->set_drr(
drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c:        if (pipe_ctx->stream_res.tg->funcs->set_drr)
drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c:                pipe_ctx->stream_res.tg->funcs->set_drr(
drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c:                if (pipe_ctx->stream_res.tg->funcs->set_drr)
drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c:                        pipe_ctx->stream_res.tg->funcs->set_drr(
drivers/gpu/drm/amd/display/dc/hwss/dcn31/dcn31_hwseq.c:        if (pipe_ctx->stream_res.tg->funcs->set_drr)
drivers/gpu/drm/amd/display/dc/hwss/dcn31/dcn31_hwseq.c:                pipe_ctx->stream_res.tg->funcs->set_drr(
drivers/gpu/drm/amd/display/dc/hwss/dcn401/dcn401_hwseq.c:      if (pipe_ctx->stream_res.tg->funcs->set_drr)
drivers/gpu/drm/amd/display/dc/hwss/dcn401/dcn401_hwseq.c:              pipe_ctx->stream_res.tg->funcs->set_drr(

>
> With best wishes,
> Tobias
>
> Tobias Jakobi (2):
>   drm/amd/display: Avoid race between dcn10_set_drr() and
>     dc_state_destruct()
>   drm/amd/display: Avoid race between dcn35_set_drr() and
>     dc_state_destruct()
>
>  .../amd/display/dc/hwss/dcn10/dcn10_hwseq.c   | 20 +++++++++++--------
>  .../amd/display/dc/hwss/dcn35/dcn35_hwseq.c   | 20 +++++++++++--------
>  2 files changed, 24 insertions(+), 16 deletions(-)