linux-kernel - Re: [PATCH] mediatek: Set default value for Panel Orientation connector prop.

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Message-ID: <CAAOTY_-b=F+moHec9sx_o5jv7XhfSd9A2crHsWGtzBdRSoiwHw@mail.gmail.com>
Date:   Fri, 17 Dec 2021 00:53:32 +0800
From:   Chun-Kuang Hu <chunkuang.hu@...nel.org>
To:     Mark Yacoub <markyacoub@...omium.org>
Cc:     Chun-Kuang Hu <chunkuang.hu@...nel.org>,
        Sean Paul <sean@...rly.run>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@...ts.infradead.org>,
        Sean Paul <seanpaul@...omium.org>,
        Mark Yacoub <markyacoub@...gle.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Matthias Brugger <matthias.bgg@...il.com>,
        DRI Development <dri-devel@...ts.freedesktop.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mediatek: Set default value for Panel Orientation
 connector prop.

Hi, Mark:

Mark Yacoub <markyacoub@...omium.org> 於 2021年12月16日 週四 上午1:25寫道：
>
> On Wed, Dec 15, 2021 at 11:14 AM Chun-Kuang Hu <chunkuang.hu@...nel.org> wrote:
> >
> > Hi, Mark:
> >
> > Mark Yacoub <markyacoub@...omium.org> 於 2021年12月14日 週二 下午11:13寫道：
> > >
> > > Hey CK, can we have this merged?
> > > Thank you!
> > >
> > > On Mon, Oct 25, 2021 at 9:13 PM Sean Paul <sean@...rly.run> wrote:
> > > >
> > > > On Fri, Oct 22, 2021 at 01:24:03PM -0400, Mark Yacoub wrote:
> > > > > From: Mark Yacoub <markyacoub@...omium.org>
> > > > >
> > > > > [Why]
> > > > > Creating the prop uses UNKNOWN as the initial value, which is not a
> > > > > supported value if the props is to be supported.
> > > > >
> > > > > [How]
> > > > > Set the panel orientation default value to NORMAL right after creating
> > > > > the prop.
> > > >
> > > > Reviewed-by: Sean Paul <seanpaul@...omium.org>
> > > >
> > > > >
> > > > > Tested on Jacuzzi(MTK)
> > > > > Fixes IGT@..._properties@..._properties-sanity-{atomic,non-atomic}
> > > > >
> > > > > Signed-off-by: Mark Yacoub <markyacoub@...omium.org>
> > > > > ---
> > > > >  drivers/gpu/drm/mediatek/mtk_dsi.c | 2 ++
> > > > >  1 file changed, 2 insertions(+)
> > > > >
> > > > > diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
> > > > > index 0ad7157660afa..b7c2528a8f41c 100644
> > > > > --- a/drivers/gpu/drm/mediatek/mtk_dsi.c
> > > > > +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
> > > > > @@ -1039,6 +1039,8 @@ static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi)
> > > > >               DRM_ERROR("Unable to init panel orientation\n");
> > > > >               goto err_cleanup_encoder;
> > > > >       }
> > > > > +     drm_connector_set_panel_orientation(dsi->connector,
> > > > > +                                         DRM_MODE_PANEL_ORIENTATION_NORMAL);
> >
> > In drm_connector_set_panel_orientation() [1], I find that the
> > orientation could be set only once. Once you set it to normal, it
> > could not be set to other orientation. Right?
> >
> Hello,
> Yeah this looks true, and makes sense according to the documentation:
> https://01.org/linuxgraphics/gfx-docs/drm/gpu/drm-kms.html#:~:text=one%20standardized%20property%3A-,panel%20orientation%3A,-On%20some%20devices
>
> Panel orientation has to do with the how the hardware is mounted, in
> contrast with the Rotation property. All the HW we have right now has
> a normal panel orientation so it makes sense to be set this way. Among

Many evidence [1], [2], [3], show that Chromebook plan to have other
orientation on mt8183, so I think you should consider this.

[1] https://patchwork.kernel.org/project/linux-mediatek/patch/20210409045314.3420733-2-hsinyi@chromium.org/
[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpu/drm/panel/panel-boe-tv101wum-nl6.c?h=v5.16-rc5#n1474
[3] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm64/boot/dts/mediatek/mt8183-kukui-krane-sku176.dts?h=v5.16-rc5#n22

Regards,
Chun-Kuang.



> other drivers, panel orientation is always set right after the
> property is initialized.
>
> > [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpu/drm/drm_connector.c?h=v5.16-rc5#n2302
> >
> > Regards,
> > Chun-Kuang.
> >
> > > > >
> > > > >       drm_connector_attach_encoder(dsi->connector, &dsi->encoder);
> > > > >
> > > > > --
> > > > > 2.33.0.1079.g6e70778dc9-goog
> > > > >
> > > >
> > > > --
> > > > Sean Paul, Software Engineer, Google / Chromium OS