linux-kernel - Re: [PATCH 1/2] Revert "drm/meson: vclk: fix calculation of 59.94 fractional rates"

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Message-ID: <bca7f65c-cdb8-48be-a800-2c36aeeeb8e3@linaro.org>
Date: Fri, 10 Jan 2025 11:13:02 +0100
From: Neil Armstrong <neil.armstrong@...aro.org>
To: Christian Hewitt <christianshewitt@...il.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
 Kevin Hilman <khilman@...libre.com>, Jerome Brunet <jbrunet@...libre.com>,
 Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
 Jernej Skrabec <jernej.skrabec@...il.com>, dri-devel@...ts.freedesktop.org,
 linux-amlogic@...ts.infradead.org, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org
Cc: stable@...r.kernel.org
Subject: Re: [PATCH 1/2] Revert "drm/meson: vclk: fix calculation of 59.94
 fractional rates"

On 10/01/2025 08:44, Christian Hewitt wrote:
> This reverts commit bfbc68e4d8695497f858a45a142665e22a512ea3.
> 
> The patch does permit the offending YUV420 @ 59.94 phy_freq and
> vclk_freq mode to match in calculations. It also results in all
> fractional rates being unavailable for use. This was unintended
> and requires the patch to be reverted.
> 
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Christian Hewitt <christianshewitt@...il.com>
> ---
>   drivers/gpu/drm/meson/meson_vclk.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/meson/meson_vclk.c b/drivers/gpu/drm/meson/meson_vclk.c
> index 2a942dc6a6dc..2a82119eb58e 100644
> --- a/drivers/gpu/drm/meson/meson_vclk.c
> +++ b/drivers/gpu/drm/meson/meson_vclk.c
> @@ -790,13 +790,13 @@ meson_vclk_vic_supported_freq(struct meson_drm *priv, unsigned int phy_freq,
>   				 FREQ_1000_1001(params[i].pixel_freq));
>   		DRM_DEBUG_DRIVER("i = %d phy_freq = %d alt = %d\n",
>   				 i, params[i].phy_freq,
> -				 FREQ_1000_1001(params[i].phy_freq/1000)*1000);
> +				 FREQ_1000_1001(params[i].phy_freq/10)*10);
>   		/* Match strict frequency */
>   		if (phy_freq == params[i].phy_freq &&
>   		    vclk_freq == params[i].vclk_freq)
>   			return MODE_OK;
>   		/* Match 1000/1001 variant */
> -		if (phy_freq == (FREQ_1000_1001(params[i].phy_freq/1000)*1000) &&
> +		if (phy_freq == (FREQ_1000_1001(params[i].phy_freq/10)*10) &&
>   		    vclk_freq == FREQ_1000_1001(params[i].vclk_freq))
>   			return MODE_OK;
>   	}
> @@ -1070,7 +1070,7 @@ void meson_vclk_setup(struct meson_drm *priv, unsigned int target,
>   
>   	for (freq = 0 ; params[freq].pixel_freq ; ++freq) {
>   		if ((phy_freq == params[freq].phy_freq ||
> -		     phy_freq == FREQ_1000_1001(params[freq].phy_freq/1000)*1000) &&
> +		     phy_freq == FREQ_1000_1001(params[freq].phy_freq/10)*10) &&
>   		    (vclk_freq == params[freq].vclk_freq ||
>   		     vclk_freq == FREQ_1000_1001(params[freq].vclk_freq))) {
>   			if (vclk_freq != params[freq].vclk_freq)

I wonder if a Fixes is also required here