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Subject: Re: [PATCH 3/3 v3] drm: bridge/dw-hdmi: Move edid reading to
 .detect() callback
To: Russell King - ARM Linux <linux@armlinux.org.uk>,
        Jose Abreu <Jose.Abreu@synopsys.com>
References: <cover.1470306826.git.joabreu@synopsys.com>
 <1bbffb944fb9ce0363f5544db31baf2a911c1c55.1470306826.git.joabreu@synopsys.com>
 <20160804104738.GR1041@n2100.armlinux.org.uk>
CC: <dri-devel@lists.freedesktop.org>,
        Carlos Palminha <CARLOS.PALMINHA@synopsys.com>,
        Archit Taneja <architt@codeaurora.org>,
        David Airlie <airlied@linux.ie>,
        Fabio Estevam <fabio.estevam@freescale.com>,
        Daniel Vetter <daniel.vetter@ffwll.ch>, Takashi Iwai <tiwai@suse.de>,
        Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>,
        Thierry Reding <treding@nvidia.com>, <linux-kernel@vger.kernel.org>
From: Jose Abreu <Jose.Abreu@synopsys.com>
Message-ID: <57A349E8.5040400@synopsys.com>
Date: Thu, 4 Aug 2016 14:58:00 +0100
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Hi Russell,


On 04-08-2016 11:47, Russell King - ARM Linux wrote:
> On Thu, Aug 04, 2016 at 11:44:51AM +0100, Jose Abreu wrote:
>> When running HDMI compliance tests we noticed that sometimes
>> the edid changes but the get_modes() function is not called
>> so the edid is not updated. Moving the edid reading to the
>> detect() callback ensures that the edid is correctly updated
>> after an hotplug.
> Wouldn't this be a bug in the higher levels of DRM?
>

I am not sure if this is a bug in DRM or a bad implementation of
dw-hdmi. I've seen at least two more drivers that do the edid
reading at the .detect() callback: nouveau and gma500. This is
noticeable if while sending video the edid changes like in a
compliance environment. In the environment that I tested I was
sending video and swapped an edid that had support for AI packets
to another one without support and I noticed that although the
hotplug is generated the edid was not being updated.

Best regards,
Jose Miguel Abreu