Date:   Wed, 1 Jul 2020 00:26:49 +0800
From:   Chun-Kuang Hu <chunkuang.hu@...nel.org>
To:     Enric Balletbo i Serra <enric.balletbo@...labora.com>
Cc:     Sam Ravnborg <sam@...nborg.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Collabora Kernel ML <kernel@...labora.com>,
        Chun-Kuang Hu <chunkuang.hu@...nel.org>,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        Nicolas Boichat <drinkcat@...omium.org>,
        Jonas Karlman <jonas@...boo.se>,
        David Airlie <airlied@...ux.ie>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        DRI Development <dri-devel@...ts.freedesktop.org>,
        Neil Armstrong <narmstrong@...libre.com>,
        Andrzej Hajda <a.hajda@...sung.com>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@...ts.infradead.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Hsin-Yi Wang <hsinyi@...omium.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [RESEND PATCH v4 0/7] Convert mtk-dsi to drm_bridge API and get
 EDID for ps8640 bridge

Hi, Enric:

Enric Balletbo i Serra <enric.balletbo@...labora.com> 於 2020年6月30日 週二 下午10:34寫道：
>
> Hi Sam, Chun-Kuan,
>
> On 20/6/20 23:33, Sam Ravnborg wrote:
> > Hi Enric
> >
> > On Mon, Jun 15, 2020 at 10:31:01PM +0200, Enric Balletbo i Serra wrote:
> >> (This resend is to fix some trivial conflicts due the merge window)
> >>
> >> The PS8640 dsi-to-eDP bridge driver is using the panel bridge API,
> >> however, not all the components in the chain have been ported to the
> >> drm_bridge API. Actually, when a panel is attached the default panel's mode
> >> is used, but in some cases we can't get display up if mode getting from
> >> eDP control EDID is not chosen.
> >>
> >> This series address that problem, first implements the .get_edid()
> >> callback in the PS8640 driver (which is not used until the conversion is
> >> done) and then, converts the Mediatek DSI driver to use the drm_bridge
> >> API.
> >>
> >> As far as I know, we're the only users of the mediatek dsi driver in
> >> mainline, so should be safe to switch to the new chain of drm_bridge API
> >> unconditionally.
> >>
> >> The patches has been tested on a Acer Chromebook R13 (Elm) running a
> >> Chrome OS userspace and checking that the valid EDID mode reported by
> >> the bridge is selected.
> >>
> >> Changes in v4:
> >> - Remove double call to drm_encoder_init(). (Chun-Kuang Hu)
> >> - Cleanup the encoder in mtk_dsi_unbind(). (Chun-Kuang Hu)
> >>
> >> Changes in v3:
> >> - Replace s/bridge/next bridge/ for comment. (Laurent Pinchart)
> >> - Add the bridge.type. (Laurent Pinchart)
> >> - Use next_bridge field to store the panel bridge. (Laurent Pinchart)
> >> - Add the bridge.type field. (Laurent Pinchart)
> >> - This patch requires https://lkml.org/lkml/2020/4/16/2080 to work
> >>   properly.
> >> - Move the bridge.type line to the patch that adds drm_bridge support. (Laurent Pinchart)
> >>
> >> Changes in v2:
> >> - Do not set connector_type for panel here. (Sam Ravnborg)
> >>
> >> Enric Balletbo i Serra (7):
> >>   drm/bridge: ps8640: Get the EDID from eDP control
> >>   drm/bridge_connector: Set default status connected for eDP connectors
> >>   drm/mediatek: mtk_dsi: Rename bridge to next_bridge
> >>   drm/mediatek: mtk_dsi: Convert to bridge driver
> >>   drm/mediatek: mtk_dsi: Use simple encoder
> >>   drm/mediatek: mtk_dsi: Use the drm_panel_bridge API
> >>   drm/mediatek: mtk_dsi: Create connector for bridges
> >
> > Patch seems ready to apply. Will they be applied to a mediatek tree
> > or to drm-misc-next?
> > Or shall we take the first two patches via drm-misc-next, and the
> > remaning via a mediatek tree? (I hope not)
> >
>
> I think the only concern is from Chun-Kuan regarding patch 7/7 "drm/mediatek:
> mtk_dsi: Create connector for bridges" whether we should support the old API or
> not, but the discussion stalled.
>

I get more clear now. In patch 7/7,

ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL,
                                        DRM_BRIDGE_ATTACH_NO_CONNECTOR);

this would call into mtk_dsi_bridge_attach() first, and then call into
panel_bridge_attach() next. So panel_bridge_attach() would receive
DRM_BRIDGE_ATTACH_NO_CONNECTOR and it return immediately so it does
not call drm_panel_attach(). So where do you call drm_panel_attach()?

Regards,
Chun-Kuang.

> Thanks,
>  Enric
>
>
>
> >       Sam
> >
> >
> >>
> >>  drivers/gpu/drm/bridge/parade-ps8640.c |  12 ++
> >>  drivers/gpu/drm/drm_bridge_connector.c |   1 +
> >>  drivers/gpu/drm/mediatek/mtk_dsi.c     | 269 ++++++++-----------------
> >>  3 files changed, 97 insertions(+), 185 deletions(-)
> >>
> >> --
> >> 2.27.0
> >>
> >> _______________________________________________
> >> dri-devel mailing list
> >> dri-devel@...ts.freedesktop.org
> >> https://lists.freedesktop.org/mailman/listinfo/dri-devel
> >

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