Re: [PATCH] drm/meson: add support for 2560x1440 resolution output

From: Christian Hewitt <christianshewitt@gmail.com>
To: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Cc: Neil Armstrong <neil.armstrong@linaro.org>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Maxime Ripard <mripard@kernel.org>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	David Airlie <airlied@gmail.com>, Simona Vetter <simona@ffwll.ch>,
	Kevin Hilman <khilman@baylibre.com>,
	Jerome Brunet <jbrunet@baylibre.com>,
	dri-devel@lists.freedesktop.org,
	linux-amlogic@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, Dongjin Kim <tobetter@gmail.com>
Subject: Re: [PATCH] drm/meson: add support for 2560x1440 resolution output
Date: Mon, 29 Sep 2025 03:57:51 +0400	[thread overview]
Message-ID: <C8A273D4-5F5F-4BD8-911A-67EC9C3FF1F4@gmail.com> (raw)
In-Reply-To: <CAFBinCCsTqsn06A5oVXGTW6PgmSQH0bHE+8PSftyWNRAbYUTcA@mail.gmail.com>

> On 29 Sep 2025, at 1:24 am, Martin Blumenstingl <martin.blumenstingl@googlemail.com> wrote:
> 
> Hi Christian,
> 
> On Sat, Sep 27, 2025 at 3:02 PM Christian Hewitt
> <christianshewitt@gmail.com> wrote:
> [...]
>> @@ -894,6 +908,10 @@ static void meson_vclk_set(struct meson_drm *priv,
>>                        m = 0xf7;
>>                        frac = vic_alternate_clock ? 0x8148 : 0x10000;
>>                        break;
>> +               case 4830000:
>> +                       m = 0xc9;
>> +                       frac = 0xd560;
>> +                       break;
> Initially I thought this was wrong because it's only added for the
> G12A (which is also used on G12B and SM1) code-path, leaving out the
> GX SoCs.
> 
> Was the 2560x1440 mode tested on a computer monitor or a TV?
> I suspect it's the former, so I think it expected the code to take the
> MESON_VCLK_TARGET_DMT path, which automatically calculates m and frac.
> 
> I'll give it a try on Friday as I do have a computer monitor with that
> resolution - so any hints for testing are welcome!

The original patch is from Hardkernel sources - I’ve picked it several
years ago and then updated values semi-recently after 1000ULL changes.
The user who originally requested that I cherry-pick it (and tested it)
was using an Odroid N2+ board (G12B) with a Dell monitor IIRC. It’s not
tested by myself as I only have TV’s not monitors, so it will be good
to have your confirmation (either way). If it’s wrong I’ll be happy to
drop it - I’m just trying to upstream and offload some longer-running
and allegedly good patches in the LibreELEC kernel patchset.

Christian
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