Quoting Kuogee Hsieh (2021-07-28 14:30:54)
> 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.
>
Please add a Fixes tag.
> Signed-off-by: Kuogee Hsieh <khsieh@xxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/msm/dp/dp_display.c | 23 +++++++++++++++++++++--
> 1 file changed, 21 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index 2b660e9..9bcb261 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -1308,6 +1308,17 @@ static int dp_display_remove(struct platform_device *pdev)
> return 0;
> }
>
> +static int dp_get_sink_count(struct dp_display_private *dp)
> +{
> + u8 sink_count;
> +
> + sink_count = drm_dp_read_sink_count(dp->aux);
drm_dp_read_sink_count() returns an int, not a u8. Comparing a u8 to
less than zero doesn't make any sense as it isn't signed.
> + if (sink_count < 0)
> + return 0;
> +
> + return sink_count;
> +}
We can drop this function and just have an int count in dp_pm_resume()
that is compared to < 0 and then ignored.
> +
> static int dp_pm_resume(struct device *dev)
> {
> struct platform_device *pdev = to_platform_device(dev);
> @@ -1327,14 +1338,22 @@ static int dp_pm_resume(struct device *dev)
>
> 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 ((status = dp_catalog_link_is_connected(dp->catalog)))
> + dp->link->sink_count = dp_get_sink_count(dp);
Do we need to call drm_dp_read_sink_count_cap() as well?
> + else
> + dp->link->sink_count = 0;
> /*
> * can not declared display is connected unless
> * HDMI cable is plugged in and sink_count of
> * dongle become 1
> */
> - if (status && dp->link->sink_count)
Is 'status' used anymore? If not, please remove it.
> + if (dp->link->sink_count)
> dp->dp_display.is_connected = true;
> else
> dp->dp_display.is_connected = false;
