linux-kernel - Re: [PATCH 5/7] drm/msm/dp: return correct edid checksum after corrupted edid checksum read

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Date:   Fri, 09 Jul 2021 11:16:28 -0700
From:   khsieh@...eaurora.org
To:     Stephen Boyd <swboyd@...omium.org>
Cc:     dri-devel@...ts.freedesktop.org, robdclark@...il.com,
        sean@...rly.run, abhinavk@...eaurora.org, aravindh@...eaurora.org,
        airlied@...ux.ie, daniel@...ll.ch, bjorn.andersson@...aro.org,
        linux-arm-msm@...r.kernel.org, freedreno@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/7] drm/msm/dp: return correct edid checksum after
 corrupted edid checksum read

On 2021-07-08 00:14, Stephen Boyd wrote:
> Quoting Kuogee Hsieh (2021-07-06 10:20:18)
>> Response with correct edid checksum saved at connector after corrupted 
>> edid
>> checksum read. This fixes Link Layer CTS cases 4.2.2.3, 4.2.2.6.
>> 
>> Signed-off-by: Kuogee Hsieh <khsieh@...eaurora.org>
>> ---
>>  drivers/gpu/drm/msm/dp/dp_panel.c | 9 +++++++--
>>  1 file changed, 7 insertions(+), 2 deletions(-)
>> 
>> diff --git a/drivers/gpu/drm/msm/dp/dp_panel.c 
>> b/drivers/gpu/drm/msm/dp/dp_panel.c
>> index 88196f7..0fdb551 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_panel.c
>> +++ b/drivers/gpu/drm/msm/dp/dp_panel.c
>> @@ -271,7 +271,7 @@ static u8 dp_panel_get_edid_checksum(struct edid 
>> *edid)
>>  {
>>         struct edid *last_block;
>>         u8 *raw_edid;
>> -       bool is_edid_corrupt;
>> +       bool is_edid_corrupt = false;
>> 
>>         if (!edid) {
>>                 DRM_ERROR("invalid edid input\n");
>> @@ -303,7 +303,12 @@ void dp_panel_handle_sink_request(struct dp_panel 
>> *dp_panel)
>>         panel = container_of(dp_panel, struct dp_panel_private, 
>> dp_panel);
>> 
>>         if (panel->link->sink_request & DP_TEST_LINK_EDID_READ) {
>> -               u8 checksum = 
>> dp_panel_get_edid_checksum(dp_panel->edid);
>> +               u8 checksum;
>> +
>> +               if (dp_panel->edid)
>> +                       checksum = 
>> dp_panel_get_edid_checksum(dp_panel->edid);
>> +               else
>> +                       checksum = 
>> dp_panel->connector->real_edid_checksum;
>> 
>>                 dp_link_send_edid_checksum(panel->link, checksum);
> 
> It looks like this can be drm_dp_send_real_edid_checksum()? Then we
> don't have to look at the connector internals sometimes and can drop
> dp_panel_get_edid_checksum() entirely?
you still need to pass read edid checksum into 
drm_dp_send_real_edid_checksum().
> 
>>                 dp_link_send_test_response(panel->link);