Re: [RFC PATCH 3/6] drm/dp: Add is_hpd_asserted() callback to struct drm_dp_aux

[Dmitry Baryshkov]

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@xxxxxxxxxx>
> Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx>

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

> ---
>
>   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