linux-kernel - Re: [PATCH v6 10/11] drm/mediatek: dp: Add .wait_hpd

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Message-ID: <a3502c0b-d0e8-9166-b6b4-8f40650636c7@baylibre.com>
Date:   Thu, 20 Jul 2023 17:03:49 +0200
From:   Alexandre Mergnat <amergnat@...libre.com>
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>, chunkuang.hu@...nel.org
Cc:     p.zabel@...gutronix.de, airlied@...il.com, daniel@...ll.ch,
        matthias.bgg@...il.com, dri-devel@...ts.freedesktop.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, kernel@...labora.com,
        wenst@...omium.org, nfraprado@...labora.com
Subject: Re: [PATCH v6 10/11] drm/mediatek: dp: Add .wait_hpd_asserted() for
 AUX bus

Reviewed-by: Alexandre Mergnat <amergnat@...libre.com>

On 17/07/2023 16:14, AngeloGioacchino Del Regno wrote:
> In order to support usecases in which the panel regulator can be
> switched on and off to save power, and usecases in which the panel
> regulator is off at boot, add a .wait_hpd_asserted() callback for
> the AUX bus: this will make sure to wait until the panel is fully
> ready after power-on before trying to communicate with it.
> 
> Also, parse the eDP display capabilities in that callback, so that
> we can also avoid using the .get_edid() callback from this bridge.
> 
> Since at this point the hpd machinery is performed in the new hpd
> callback and the detection and edid reading are done outside of
> this driver, assign the DRM_BRIDGE_OP_{DETECT, EDID, HPD} ops and
> register the bridge unconditionally at probe time only if we are
> probing full DisplayPort and not eDP while, for the latter, we
> register the bridge in the .done_probing() callback and only if
> the panel was found and triggered HPD.

-- 
Regards,
Alexandre