linux-kernel - Re: [PATCH] drm/amd/display: do not allocate display_mode

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Date:   Fri, 17 Jan 2020 12:59:39 +0200
From:   Dor Askayo <dor.askayo@...il.com>
To:     amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org,
        Alex Deucher <alexander.deucher@....com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>
Cc:     Harry Wentland <harry.wentland@....com>,
        Leo Li <sunpeng.li@....com>,
        Christian König <christian.koenig@....com>,
        "David (ChunMing) Zhou" <David1.Zhou@....com>
Subject: Re: [PATCH] drm/amd/display: do not allocate display_mode_lib unnecessarily

On Sat, Jan 4, 2020 at 2:23 PM Dor Askayo <dor.askayo@...il.com> wrote:
>
> This allocation isn't required and can fail when resuming from suspend.
>
> Bug: https://gitlab.freedesktop.org/drm/amd/issues/1009
> Signed-off-by: Dor Askayo <dor.askayo@...il.com>
> ---
>  drivers/gpu/drm/amd/display/dc/core/dc.c | 17 +++++++++--------
>  1 file changed, 9 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/core/dc.c b/drivers/gpu/drm/amd/display/dc/core/dc.c
> index dd4731ab935c..83ebb716166b 100644
> --- a/drivers/gpu/drm/amd/display/dc/core/dc.c
> +++ b/drivers/gpu/drm/amd/display/dc/core/dc.c
> @@ -2179,12 +2179,7 @@ void dc_set_power_state(
>         enum dc_acpi_cm_power_state power_state)
>  {
>         struct kref refcount;
> -       struct display_mode_lib *dml = kzalloc(sizeof(struct display_mode_lib),
> -                                               GFP_KERNEL);
> -
> -       ASSERT(dml);
> -       if (!dml)
> -               return;
> +       struct display_mode_lib *dml;
>
>         switch (power_state) {
>         case DC_ACPI_CM_POWER_STATE_D0:
> @@ -2206,6 +2201,12 @@ void dc_set_power_state(
>                  * clean state, and dc hw programming optimizations will not
>                  * cause any trouble.
>                  */
> +               dml = kzalloc(sizeof(struct display_mode_lib),
> +                               GFP_KERNEL);
> +
> +               ASSERT(dml);
> +               if (!dml)
> +                       return;
>
>                 /* Preserve refcount */
>                 refcount = dc->current_state->refcount;
> @@ -2219,10 +2220,10 @@ void dc_set_power_state(
>                 dc->current_state->refcount = refcount;
>                 dc->current_state->bw_ctx.dml = *dml;
>
> +               kfree(dml);
> +
>                 break;
>         }
> -
> -       kfree(dml);
>  }
>
>  void dc_resume(struct dc *dc)
> --
> 2.24.1
>

I've been running with this fix applied on top of Fedora's
5.3.16-300.fc31.x86_64 kernel for
the past two weeks, suspending and resuming often. This the first time
since I bought my
RX 580 8GB more than a year ago that I can suspend and resume reliably.

I'd appreciate a quick review for the above, it really is a trivial change.

Thanks,
Dor