linux-kernel - Re: [PATCH RFC v2 0/2] drm/meson: vclk: revert and re-fix vclk calculations

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Message-ID: <b88bfe5a-9256-4de0-822b-b22d74dfdec0@linaro.org>
Date: Tue, 22 Apr 2025 09:03:04 +0200
From: neil.armstrong@...aro.org
To: Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
 dri-devel@...ts.freedesktop.org, linux-amlogic@...ts.infradead.org
Cc: christianshewitt@...il.com, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC v2 0/2] drm/meson: vclk: revert and re-fix vclk
 calculations

On 21/04/2025 22:12, Martin Blumenstingl wrote:
> This is a successor of a previous patchset by Christian [0]
> 
> Patch 1 reverts a previous fix for loss of HDMI sync when playing YUV420
> @ 59.94 media. The patch does resolve a calculation issue. It also makes
> all fractional rates invalid which is a bigger problem.
> 
> Patch 2 changes the whole drm/meson driver to use Hz as unit for clocks/
> frequencies. And importantly it uses the relevant 64-bit maths helpers so
> the code can still be compiled using for 32-bit ARM.
> Maxime previously suggested using drm_hdmi_compute_mode_clock(). That's
> still something to implement with future patches.
> 
> Neil, I'd like to hear your feedback on this approach.
> 
> 
> [0] https://lore.kernel.org/linux-amlogic/20250110074458.3624094-1-christianshewitt@gmail.com/
> 
> 
> Christian Hewitt (1):
>    Revert "drm/meson: vclk: fix calculation of 59.94 fractional rates"
> 
> Martin Blumenstingl (1):
>    drm/meson: use unsigned long long / Hz for frequency types
> 
>   drivers/gpu/drm/meson/meson_drv.c          |   2 +-
>   drivers/gpu/drm/meson/meson_drv.h          |   2 +-
>   drivers/gpu/drm/meson/meson_encoder_hdmi.c |  29 +--
>   drivers/gpu/drm/meson/meson_vclk.c         | 195 +++++++++++----------
>   drivers/gpu/drm/meson/meson_vclk.h         |  13 +-
>   5 files changed, 126 insertions(+), 115 deletions(-)
> 

Thanks for re-spinning, will apply.

Reviewed-by: Neil Armstrong <neil.armstrong@...aro.org>

Thanks !