linux-kernel - Re: [PATCH] drm/ssd130x: Use shadow-buffer helpers when managing plane's state

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Message-ID: <0ce32153-cfc0-e701-3863-803fcdb897ff@suse.de>
Date:   Thu, 27 Jul 2023 17:03:35 +0200
From:   Thomas Zimmermann <tzimmermann@...e.de>
To:     Javier Martinez Canillas <javierm@...hat.com>,
        linux-kernel@...r.kernel.org
Cc:     Arnd Bergmann <arnd@...db.de>, Maxime Ripard <mripard@...nel.org>,
        dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH] drm/ssd130x: Use shadow-buffer helpers when managing
 plane's state

Hi Javier

Am 27.07.23 um 16:04 schrieb Javier Martinez Canillas:
> The commit 45b58669e532 ("drm/ssd130x: Allocate buffer in the plane's
> .atomic_check() callback") moved the buffers allocation to be done in
> the primary plane's .atomic_check() callback.
> 
> But it missed that since the driver uses a shadow-buffered plane, the
> __drm_gem_{reset,duplicate,destroy}_shadow_plane() helper functions
> must be used in the struct drm_plane_funcs handlers.
> 
> This was missed because the mentioned commit did not remove the macro
> DRM_GEM_SHADOW_PLANE_FUNCS, which leads to the custom plane's atomic
> state management handlers to not be used.
> 
> Fixes: 45b58669e532 ("drm/ssd130x: Allocate buffer in the plane's .atomic_check() callback")
> Reported-by: Arnd Bergmann <arnd@...db.de>

Reported-by needs to be followed by

Closes: <url>

where <url> would point to Arnd's bug report on dri-devel.

> Suggested-by: Thomas Zimmermann <tzimmermann@...e.de>
> Signed-off-by: Javier Martinez Canillas <javierm@...hat.com>

This looks correct now. Thanks for fixing this bug quickly. With the 
Close added:

Reviewed-by: Thomas Zimmermann <tzimmermann@...e.de>

Best regards
Thomas

> ---
> 
>   drivers/gpu/drm/solomon/ssd130x.c | 16 +++++++++-------
>   1 file changed, 9 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/solomon/ssd130x.c b/drivers/gpu/drm/solomon/ssd130x.c
> index d2f8dd6a6347..971c425340c1 100644
> --- a/drivers/gpu/drm/solomon/ssd130x.c
> +++ b/drivers/gpu/drm/solomon/ssd130x.c
> @@ -142,7 +142,7 @@ const struct ssd130x_deviceinfo ssd130x_variants[] = {
>   EXPORT_SYMBOL_NS_GPL(ssd130x_variants, DRM_SSD130X);
>   
>   struct ssd130x_plane_state {
> -	struct drm_plane_state base;
> +	struct drm_shadow_plane_state base;
>   	/* Intermediate buffer to convert pixels from XRGB8888 to HW format */
>   	u8 *buffer;
>   	/* Buffer to store pixels in HW format and written to the panel */
> @@ -151,7 +151,7 @@ struct ssd130x_plane_state {
>   
>   static inline struct ssd130x_plane_state *to_ssd130x_plane_state(struct drm_plane_state *state)
>   {
> -	return container_of(state, struct ssd130x_plane_state, base);
> +	return container_of(state, struct ssd130x_plane_state, base.base);
>   }
>   
>   static inline struct ssd130x_device *drm_to_ssd130x(struct drm_device *drm)
> @@ -689,11 +689,12 @@ static void ssd130x_primary_plane_reset(struct drm_plane *plane)
>   	if (!ssd130x_state)
>   		return;
>   
> -	__drm_atomic_helper_plane_reset(plane, &ssd130x_state->base);
> +	__drm_gem_reset_shadow_plane(plane, &ssd130x_state->base);
>   }
>   
>   static struct drm_plane_state *ssd130x_primary_plane_duplicate_state(struct drm_plane *plane)
>   {
> +	struct drm_shadow_plane_state *new_shadow_plane_state;
>   	struct ssd130x_plane_state *old_ssd130x_state;
>   	struct ssd130x_plane_state *ssd130x_state;
>   
> @@ -709,9 +710,11 @@ static struct drm_plane_state *ssd130x_primary_plane_duplicate_state(struct drm_
>   	ssd130x_state->buffer = NULL;
>   	ssd130x_state->data_array = NULL;
>   
> -	__drm_atomic_helper_plane_duplicate_state(plane, &ssd130x_state->base);
> +	new_shadow_plane_state = &ssd130x_state->base;
>   
> -	return &ssd130x_state->base;
> +	 __drm_gem_duplicate_shadow_plane_state(plane, new_shadow_plane_state);
> +
> +	return &new_shadow_plane_state->base;
>   }
>   
>   static void ssd130x_primary_plane_destroy_state(struct drm_plane *plane,
> @@ -722,7 +725,7 @@ static void ssd130x_primary_plane_destroy_state(struct drm_plane *plane,
>   	kfree(ssd130x_state->data_array);
>   	kfree(ssd130x_state->buffer);
>   
> -	__drm_atomic_helper_plane_destroy_state(&ssd130x_state->base);
> +	__drm_gem_destroy_shadow_plane_state(&ssd130x_state->base);
>   
>   	kfree(ssd130x_state);
>   }
> @@ -741,7 +744,6 @@ static const struct drm_plane_funcs ssd130x_primary_plane_funcs = {
>   	.atomic_duplicate_state = ssd130x_primary_plane_duplicate_state,
>   	.atomic_destroy_state = ssd130x_primary_plane_destroy_state,
>   	.destroy = drm_plane_cleanup,
> -	DRM_GEM_SHADOW_PLANE_FUNCS,
>   };
>   
>   static enum drm_mode_status ssd130x_crtc_helper_mode_valid(struct drm_crtc *crtc,

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)

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