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SubjectRe: [RFC PATCH 3/6] drm/dp: Add is_hpd_asserted() callback to struct drm_dp_aux
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On 09/04/2022 05:36, Douglas Anderson wrote:
> Sometimes it's useful for users of the DP AUX bus (like panels) to be
> able to poll HPD. Let's add a callback that allows DP AUX busses
> drivers to provide this.
>
> Suggested-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> Signed-off-by: Douglas Anderson <dianders@chromium.org>

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

> ---
>
> include/drm/dp/drm_dp_helper.h | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/include/drm/dp/drm_dp_helper.h b/include/drm/dp/drm_dp_helper.h
> index dad1442c91df..a12951319573 100644
> --- a/include/drm/dp/drm_dp_helper.h
> +++ b/include/drm/dp/drm_dp_helper.h
> @@ -2021,6 +2021,20 @@ struct drm_dp_aux {
> ssize_t (*transfer)(struct drm_dp_aux *aux,
> struct drm_dp_aux_msg *msg);
>
> + /**
> + * @is_hpd_asserted: returns true if HPD is asserted
> + *
> + * This is mainly useful for eDP panels drivers to query whether
> + * an eDP panel has finished powering on. This is an optional function.
> + *
> + * NOTE: this function specifically reports the state of the HPD pin
> + * that's associated with the DP AUX channel. This is different from
> + * the HPD concept in much of the rest of DRM which is more about
> + * physical presence of a display. For eDP, for instance, a display is
> + * assumed always present even if the HPD pin is deasserted.
> + */
> + bool (*is_hpd_asserted)(struct drm_dp_aux *aux);
> +
> /**
> * @i2c_nack_count: Counts I2C NACKs, used for DP validation.
> */


--
With best wishes
Dmitry

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