linux-kernel - Re: [PATCH 3/3] drm/vc4: Correct generation check in vc4_hvs_lut

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Message-ID: <a0922d76-0dc0-46a5-8408-a8eda3a07f26@igalia.com>
Date: Tue, 8 Oct 2024 22:30:49 -0300
From: Maíra Canal <mcanal@...lia.com>
To: Dave Stevenson <dave.stevenson@...pberrypi.com>,
 Maxime Ripard <mripard@...nel.org>,
 Raspberry Pi Kernel Maintenance <kernel-list@...pberrypi.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>,
 Simona Vetter <simona@...ll.ch>
Cc: Marek Szyprowski <m.szyprowski@...sung.com>,
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] drm/vc4: Correct generation check in vc4_hvs_lut_load

Hi Dave,

On 10/8/24 13:44, Dave Stevenson wrote:
> Commit 24c5ed3ddf27 ("drm/vc4: Introduce generation number enum")
> incorrectly swapped a check of hvs->vc4->is_vc5 to
> hvs->vc4->gen == VC4_GEN_4 in vc4_hvs_lut_load, hence breaking
> loading the gamma look up table on Pi0-3.
> 
> Correct that conditional.
> 
> Fixes: 24c5ed3ddf27 ("drm/vc4: Introduce generation number enum")
> Signed-off-by: Dave Stevenson <dave.stevenson@...pberrypi.com>
> ---
>   drivers/gpu/drm/vc4/vc4_hvs.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/vc4/vc4_hvs.c b/drivers/gpu/drm/vc4/vc4_hvs.c
> index c5ebc317188a..1edf6e3fa7e6 100644
> --- a/drivers/gpu/drm/vc4/vc4_hvs.c
> +++ b/drivers/gpu/drm/vc4/vc4_hvs.c
> @@ -224,7 +224,7 @@ static void vc4_hvs_lut_load(struct vc4_hvs *hvs,
>   	if (!drm_dev_enter(drm, &idx))
>   		return;
>   
> -	if (hvs->vc4->gen == VC4_GEN_4)
> +	if (hvs->vc4->gen != VC4_GEN_4)

Again, another nit: I believe `hvs->vc4->gen > VC4_GEN_4` is more
semantic and it's the standard I usually see around the driver.

But this isn't critical, so:

Reviewed-by: Maíra Canal <mcanal@...lia.com>

Best Regards,
- Maíra

>   		goto exit;
>   
>   	/* The LUT memory is laid out with each HVS channel in order,
>