linux-kernel - Re: [PATCH] drm/mediatek: hdmi: Filter interlaced resolutions

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Message-ID: <20170523131243.5bjz5n4uv73r2l7j@phenom.ffwll.local>
Date:   Tue, 23 May 2017 15:12:43 +0200
From:   Daniel Vetter <daniel@...ll.ch>
To:     CK Hu <ck.hu@...iatek.com>
Cc:     Bibby Hsieh <bibby.hsieh@...iatek.com>,
        David Airlie <airlied@...ux.ie>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        Yingjoe Chen (陳英洲) 
        <Yingjoe.Chen@...iatek.com>,
        Cawa Cheng (鄭曄禧) 
        <cawa.cheng@...iatek.com>, Daniel Kurtz <djkurtz@...omium.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        YT Shen (沈岳霆) <Yt.Shen@...iatek.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Mao Huang <littlecvr@...omium.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Sascha Hauer <kernel@...gutronix.de>
Subject: Re: [PATCH] drm/mediatek: hdmi: Filter interlaced resolutions

On Tue, May 23, 2017 at 05:28:15PM +0800, CK Hu wrote:
> Hi, Bibby:
> 
> I've applied this patch to my branch mediatek-drm-fixes-4.12-rc1,
> thanks.
> 
> Regards,
> CK
> 
> On Tue, 2017-01-24 at 13:10 +0800, Bibby Hsieh wrote:
> > Current Mediatek DRM driver does not support interlaced mode, and
> > will hang if such resolution is used: Filter those to prevent
> > kernel hangs, until the DRM driver is fixed properly.
> > 
> > Signed-off-by: Bibby Hsieh <bibby.hsieh@...iatek.com>
> > ---
> >  drivers/gpu/drm/mediatek/mtk_hdmi.c | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/mediatek/mtk_hdmi.c b/drivers/gpu/drm/mediatek/mtk_hdmi.c
> > index 0e8c4d9..e33678d 100644
> > --- a/drivers/gpu/drm/mediatek/mtk_hdmi.c
> > +++ b/drivers/gpu/drm/mediatek/mtk_hdmi.c
> > @@ -1244,6 +1244,8 @@ static int mtk_hdmi_conn_mode_valid(struct drm_connector *conn,
> >  			return MODE_BAD;
> >  	}
> >  
> > +	if (mode->flags & DRM_MODE_FLAG_INTERLACE)
> > +		return MODE_NO_INTERLACE;
> >  	if (mode->clock < 27000)
> >  		return MODE_CLOCK_LOW;
> >  	if (mode->clock > 297000)

You probably want to check out Jose's mode_valid work, since only
filtering in the connector's ->mode_valid callback isn't enough. You also
need to filter in ->mode_fixup (or some other place called at atomic_check
time).
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch