linux-kernel - Re: [PATCH 12/12] drm/amd/display: Remove two unused variables 'result_write_min_hblank' and 'hblank

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Message-ID: <CADnq5_OG8pDyYruc4VCpd_eG8MxZUDf+nPr4zTy+u-7-a5L6uw@mail.gmail.com>
Date:   Mon, 27 Mar 2023 19:53:36 -0400
From:   Alex Deucher <alexdeucher@...il.com>
To:     Caio Novais <caionovais@....br>
Cc:     amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, Felipe Clark <felipe.clark@....com>,
        Wenjing Liu <wenjing.liu@....com>,
        Maíra Canal <mairacanal@...eup.net>,
        Mario Limonciello <mario.limonciello@....com>,
        Jun Lei <Jun.Lei@....com>, David Airlie <airlied@...il.com>,
        Charlene Liu <Charlene.Liu@....com>,
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        Rodrigo Siqueira <Rodrigo.Siqueira@....com>,
        Taimur Hassan <Syed.Hassan@....com>,
        Aurabindo Pillai <aurabindo.pillai@....com>,
        Alvin Lee <alvin.lee2@....com>,
        George Shen <George.Shen@....com>,
        Hamza Mahfooz <hamza.mahfooz@....com>,
        Chaitanya Dhere <chaitanya.dhere@....com>,
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        Hawking Zhang <Hawking.Zhang@....com>
Subject: Re: [PATCH 12/12] drm/amd/display: Remove two unused variables
 'result_write_min_hblank' and 'hblank_size'

On Mon, Mar 27, 2023 at 7:36 PM Caio Novais <caionovais@....br> wrote:
>
> Compiling AMD GPU drivers displays a warning:
>
> drivers/gpu/drm/amd/amdgpu/../display/dc/link/protocols/link_dp_capability.c: In function ‘dpcd_set_source_specific_data’:
> drivers/gpu/drm/amd/amdgpu/../display/dc/link/protocols/link_dp_capability.c:1290:32: warning: variable ‘result_write_min_hblank’ set but not used [-Wunused-but-set-variable]
>
> Get rid of it by removing the variable 'result_write_min_hblank' and 'hblank_size'.
>
> Signed-off-by: Caio Novais <caionovais@....br>
> ---
>  .../drm/amd/display/dc/link/protocols/link_dp_capability.c | 7 -------
>  1 file changed, 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_capability.c b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_capability.c
> index d4370856f164..7392fcf17653 100644
> --- a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_capability.c
> +++ b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_capability.c
> @@ -1287,7 +1287,6 @@ void dc_link_overwrite_extended_receiver_cap(
>  void dpcd_set_source_specific_data(struct dc_link *link)
>  {
>         if (!link->dc->vendor_signature.is_valid) {
> -               enum dc_status result_write_min_hblank = DC_NOT_SUPPORTED;
>                 struct dpcd_amd_signature amd_signature = {0};
>                 struct dpcd_amd_device_id amd_device_id = {0};
>
> @@ -1324,16 +1323,10 @@ void dpcd_set_source_specific_data(struct dc_link *link)
>                 if (link->ctx->dce_version >= DCN_VERSION_2_0 &&
>                         link->dc->caps.min_horizontal_blanking_period != 0) {
>
> -                       uint8_t hblank_size = (uint8_t)link->dc->caps.min_horizontal_blanking_period;
> -
> -                       result_write_min_hblank = core_link_write_dpcd(link,
> -                               DP_SOURCE_MINIMUM_HBLANK_SUPPORTED, (uint8_t *)(&hblank_size),
> -                               sizeof(hblank_size));

This writes to the monitor.  We shouldn't remove this.

>                 }
>                 DC_TRACE_LEVEL_MESSAGE(DAL_TRACE_LEVEL_INFORMATION,
>                                                         WPP_BIT_FLAG_DC_DETECTION_DP_CAPS,
>                                                         "result=%u link_index=%u enum dce_version=%d DPCD=0x%04X min_hblank=%u branch_dev_id=0x%x branch_dev_name='%c%c%c%c%c%c'",
> -                                                       result_write_min_hblank,

You are dropping information from the debug logging.  Maybe it would
be better to just flag this as maybe unused.  Also, I'd suggest
rebasing on the latest amdgpu -next branch, as I think a lot of these
were already fixed last week or the week before.

Alex

>                                                         link->link_index,
>                                                         link->ctx->dce_version,
>                                                         DP_SOURCE_MINIMUM_HBLANK_SUPPORTED,
> --
> 2.40.0
>