Quoting Kuogee Hsieh (2021-08-02 13:20:55)
> Currently at dp_pm_resume() is_connected state is decided base on hpd connection
> status only. This will put is_connected in wrongly "true" state at the scenario
> that dongle attached to DUT but without hmdi cable connecting to it. Fix this
> problem by adding read sink count from dongle and decided is_connected state base
> on both sink count and hpd connection status.
>
> Changes in v2:
> -- remove dp_get_sink_count() cand call drm_dp_read_sink_count()
>
> Fixes: d9aa6571b28ba ("drm/msm/dp: check sink_count before update is_connected status")
> Signed-off-by: Kuogee Hsieh <khsieh@xxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/msm/dp/dp_display.c | 18 +++++++++++++++---
> 1 file changed, 15 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index 8b69114..6dcb78e 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -1403,6 +1403,7 @@ static int dp_pm_resume(struct device *dev)
> struct msm_dp *dp_display = platform_get_drvdata(pdev);
> struct dp_display_private *dp;
> u32 status;
'status' is unused now, right? The compiler should be complaining about
unused local variables.
> + int sink_count = 0;
>
> dp = container_of(dp_display, struct dp_display_private, dp_display);
> xlog(__func__, 1,0,0, dp->core_initialized, dp_display->power_on);
> @@ -1417,15 +1418,26 @@ xlog(__func__, 1,0,0, dp->core_initialized, dp_display->power_on);
>
> dp_catalog_ctrl_hpd_config(dp->catalog);
>
> - status = dp_catalog_link_is_connected(dp->catalog);
> + /*
> + * set sink to normal operation mode -- D0
> + * before dpcd read
> + */
> + dp_link_psm_config(dp->link, &dp->panel->link_info, false);
> +
> + /* if sink conencted, do dpcd read sink count */
> + if ((status = dp_catalog_link_is_connected(dp->catalog))) {
> + sink_count = drm_dp_read_sink_count(dp->aux);
> + if (sink_count < 0)
> + sink_count = 0;
> + }
>
> + dp->link->sink_count = sink_count;
> /*
> * can not declared display is connected unless
> * HDMI cable is plugged in and sink_count of
> * dongle become 1
> */
> -xlog(__func__, 0x12,0,0, 0, dp->link->sink_count);
> - if (status && dp->link->sink_count)
> + if (dp->link->sink_count)
> dp->dp_display.is_connected = true;
> else
> dp->dp_display.is_connected = false;
