[PATCH v2] drm/meson: Fix atomic mode switching regression

[Neil Armstrong]

Hi Stable kernel team,

On 14/01/2019 16:31, Neil Armstrong wrote:
> Since commit 2bcd3ecab773 when switching mode from X11 (ubuntu mate for
> example) the display gets blurry, looking like an invalid framebuffer width.
> 
> This commit fixed atomic crtc modesetting in a totally wrong way and
> introduced a local unnecessary ->enabled crtc state.
> 
> This commit reverts the crctc _begin() and _enable() changes and simply
> adds drm_atomic_helper_commit_tail_rpm as helper.
> 
> Reported-by: Tony McKahan <tonymckahan at gmail.com>
> Suggested-by: Daniel Vetter <daniel at ffwll.ch>
> Fixes: 2bcd3ecab773 ("drm/meson: Fixes for drm_crtc_vblank_on/off support")
> Signed-off-by: Neil Armstrong <narmstrong at baylibre.com>

This fix has landed in linus master with id ce0210c12433031aba3bbacd75f4c02ab77f2004

could it be applied to 4.19 and 4.20 stable trees ?

Thanks,
Neil

> ---
>  drivers/gpu/drm/meson/meson_crtc.c | 23 ++---------------------
>  drivers/gpu/drm/meson/meson_drv.c  |  6 ++++++
>  2 files changed, 8 insertions(+), 21 deletions(-)
> 
> Changes since v1:
> - drop the unecessary local ->enabled logic
> - use drm_atomic_helper_commit_tail_rpm as atomic_commit_tail helper
> 
> diff --git a/drivers/gpu/drm/meson/meson_crtc.c b/drivers/gpu/drm/meson/meson_crtc.c
> index 75d97f1b2e8f..4f5c67f70c4d 100644
> --- a/drivers/gpu/drm/meson/meson_crtc.c
> +++ b/drivers/gpu/drm/meson/meson_crtc.c
> @@ -46,7 +46,6 @@ struct meson_crtc {
>  	struct drm_crtc base;
>  	struct drm_pending_vblank_event *event;
>  	struct meson_drm *priv;
> -	bool enabled;
>  };
>  #define to_meson_crtc(x) container_of(x, struct meson_crtc, base)
>  
> @@ -82,7 +81,8 @@ static const struct drm_crtc_funcs meson_crtc_funcs = {
>  
>  };
>  
> -static void meson_crtc_enable(struct drm_crtc *crtc)
> +static void meson_crtc_atomic_enable(struct drm_crtc *crtc,
> +				     struct drm_crtc_state *old_state)
>  {
>  	struct meson_crtc *meson_crtc = to_meson_crtc(crtc);
>  	struct drm_crtc_state *crtc_state = crtc->state;
> @@ -108,20 +108,6 @@ static void meson_crtc_enable(struct drm_crtc *crtc)
>  
>  	drm_crtc_vblank_on(crtc);
>  
> -	meson_crtc->enabled = true;
> -}
> -
> -static void meson_crtc_atomic_enable(struct drm_crtc *crtc,
> -				     struct drm_crtc_state *old_state)
> -{
> -	struct meson_crtc *meson_crtc = to_meson_crtc(crtc);
> -	struct meson_drm *priv = meson_crtc->priv;
> -
> -	DRM_DEBUG_DRIVER("\n");
> -
> -	if (!meson_crtc->enabled)
> -		meson_crtc_enable(crtc);
> -
>  	priv->viu.osd1_enabled = true;
>  }
>  
> @@ -153,8 +139,6 @@ static void meson_crtc_atomic_disable(struct drm_crtc *crtc,
>  
>  		crtc->state->event = NULL;
>  	}
> -
> -	meson_crtc->enabled = false;
>  }
>  
>  static void meson_crtc_atomic_begin(struct drm_crtc *crtc,
> @@ -163,9 +147,6 @@ static void meson_crtc_atomic_begin(struct drm_crtc *crtc,
>  	struct meson_crtc *meson_crtc = to_meson_crtc(crtc);
>  	unsigned long flags;
>  
> -	if (crtc->state->enable && !meson_crtc->enabled)
> -		meson_crtc_enable(crtc);
> -
>  	if (crtc->state->event) {
>  		WARN_ON(drm_crtc_vblank_get(crtc) != 0);
>  
> diff --git a/drivers/gpu/drm/meson/meson_drv.c b/drivers/gpu/drm/meson/meson_drv.c
> index 3ee4d4a4ecba..a74d861ddceb 100644
> --- a/drivers/gpu/drm/meson/meson_drv.c
> +++ b/drivers/gpu/drm/meson/meson_drv.c
> @@ -75,6 +75,11 @@ static const struct drm_mode_config_funcs meson_mode_config_funcs = {
>  	.fb_create           = drm_gem_fb_create,
>  };
>  
> +
> +static const struct drm_mode_config_helper_funcs meson_mode_config_helpers = {
> +	.atomic_commit_tail = drm_atomic_helper_commit_tail_rpm,
> +};
> +
>  static irqreturn_t meson_irq(int irq, void *arg)
>  {
>  	struct drm_device *dev = arg;
> @@ -266,6 +271,7 @@ static int meson_drv_bind_master(struct device *dev, bool has_components)
>  	drm->mode_config.max_width = 3840;
>  	drm->mode_config.max_height = 2160;
>  	drm->mode_config.funcs = &meson_mode_config_funcs;
> +	drm->mode_config.helper_private	= &meson_mode_config_helpers;
>  
>  	/* Hardware Initialization */
>  
>