Re: [PATCH v3 6/7] drm/atomic: Convert get_existing_state callers to get_old/new_state, v2.

From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: dri-devel@lists.freedesktop.org
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH v3 6/7] drm/atomic: Convert get_existing_state callers to get_old/new_state, v2.
Date: Tue, 17 Jan 2017 03:27:59 +0200	[thread overview]
Message-ID: <2353911.UeQs03ax0S@avalon> (raw)
In-Reply-To: <1484559464-27107-7-git-send-email-maarten.lankhorst@linux.intel.com>

Hi Maarten,

One more thing.

On Monday 16 Jan 2017 10:37:43 Maarten Lankhorst wrote:
> This is a straightforward conversion that converts all the users of
> get_existing_state in atomic core to use get_old_state or get_new_state
> 
> Changes since v1:
> - Fix using the wrong state in
> drm_atomic_helper_update_legacy_modeset_state.
> 
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> ---
>  drivers/gpu/drm/drm_atomic.c        |  6 +++---
>  drivers/gpu/drm/drm_atomic_helper.c | 39 ++++++++++++++--------------------
>  drivers/gpu/drm/drm_blend.c         |  3 +--
>  3 files changed, 22 insertions(+), 26 deletions(-)

[snip]

> diff --git a/drivers/gpu/drm/drm_atomic_helper.c
> b/drivers/gpu/drm/drm_atomic_helper.c index b26cf786ce12..1de8d5fbc8d3
> 100644
> --- a/drivers/gpu/drm/drm_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_helper.c

[snip]

> @@ -698,8 +695,7 @@ disable_outputs(struct drm_device *dev, struct
> drm_atomic_state *old_state) if (!old_conn_state->crtc)
>  			continue;
> 
> -		old_crtc_state = drm_atomic_get_existing_crtc_state(old_state,
> -								    
old_conn_state->crtc);
> +		old_crtc_state = drm_atomic_get_new_crtc_state(old_state,
> old_conn_state->crtc);

This looks wrong. I believe you should call drm_atomic_get_old_crtc_state() 
here. If I'm not mistaken drm_atomic_get_existing_crtc_state() did the right 
thing as old_state->crtcs[*].state was set to the old state by the state swap 
operation.

On the other hand, drm_atomic_helper_update_legacy_modeset_state() uses 
drm_atomic_get_new_plane_state() the same way you do here, even though it 
operates after state swap, and your changelog specifically mentions that 
you've fixed that in v2. It's getting too late to properly wrap my head around 
this, I'll let you check which option is correct (but I reserve the right to 
challenge it if your explanation isn't convincing enough ;-)).

>  		if (!old_crtc_state->active ||
>  		    !drm_atomic_crtc_needs_modeset(old_conn_state->crtc-
>state))

-- 
Regards,

Laurent Pinchart

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