Re: [PATCH 0/2] drm/tegra: Fix panel support on Venice 2 and Nyan

From: Dmitry Osipenko <digetx@gmail.com>
To: Thierry Reding <thierry.reding@gmail.com>
Cc: Thomas Graichen <thomas.graichen@gmail.com>,
	Douglas Anderson <dianders@chromium.org>,
	dri-devel@lists.freedesktop.org,
	Jon Hunter <jonathanh@nvidia.com>,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	linux-tegra@vger.kernel.org
Subject: Re: [PATCH 0/2] drm/tegra: Fix panel support on Venice 2 and Nyan
Date: Tue, 21 Dec 2021 19:45:31 +0300	[thread overview]
Message-ID: <1bac3b32-ad9b-4d10-c7fb-6aafd353cdd4@gmail.com> (raw)
In-Reply-To: <YcH+Fw9sCzCIzFIx@orome>

21.12.2021 19:17, Thierry Reding пишет:
> On Tue, Dec 21, 2021 at 06:47:31PM +0300, Dmitry Osipenko wrote:
>> 21.12.2021 13:58, Thierry Reding пишет:
>> ..
>>>>>> The panel->ddc isn't used by the new panel-edp driver unless panel is
>>>>>> compatible with "edp-panel". Hence the generic_edp_panel_probe() should
>>>>>> either fail or crash for a such "edp-panel" since panel->ddc isn't fully
>>>>>> instantiated, AFAICS.
>>>>>
>>>>> I've tested this and it works fine on Venice 2. Since that was the
>>>>> reference design for Nyan, I suspect that Nyan's will also work.
>>>>>
>>>>> It'd be great if Thomas or anyone else with access to a Nyan could
>>>>> test this to verify that.
>>>>
>>>> There is no panel-edp driver in the v5.15. The EOL of v5.15 is Oct,
>>>> 2023, hence we need to either use:
>>>
>>> All the (at least relevant) functionality that is in panel-edp was in
>>> panel-simple before it was moved to panel-edp. I've backported this set
>>> of patches to v5.15 and it works just fine there.
>>
>> Will we be able to add patch to bypass the panel's DT ddc-i2c-bus on
>> Nyan to keep the older DTBs working?
> 
> I don't see why we would want to do that. It's quite clear that the DTB
> is buggy in this case and we have a more accurate way to describe what's
> really there in hardware. In addition that more accurate representation
> also gets rid of a bug. Obviously because the bug is caused by the
> previous representation that was not accurate.
> 
> Given that we can easily replace the DTBs on these devices there's no
> reason to make this any more complicated than it has to be.

Don't you care about normal people at all? Do you assume that everyone
must to be a kernel developer to be able to use Tegra devices? :/

It's not a problem for you to figure out why display is broken, for
other people it's a problem. Usually nobody will update DTB without a
well known reason, instead device will be dusted on a shelf. In the end
you won't have any users at all.