[PATCH] drm/atomic-helper: Do not call ->mode_fixup for CRTC which will be disabled

[Daniel Vetter]

On Fri, May 27, 2016 at 05:35:54PM +0800, Liu Ying wrote:
> When a CRTC is going to be disabled, it's state may contain a display mode
> with zeroed content.  This could be reproduced by HDMI cable hotplug out
> operation with legacy fbdev support in dual display cases.  It would confuse
> driver's CRTC callback ->mode_fixup and make the total state be rejected.
> So, let's don't call the callback for the CRTC.
> 
> Signed-off-by: Liu Ying <gnuiyl at gmail.com>

Indeed this matches behaviour for encoder/bridge mode_fixup functions.
Patch merged to drm-misc.

A doc patch for the kernel doc of all the mode_fixup (and the encoder's
atomic_check) that this is only called when enabling a mode would be
awesome.
-Daniel

> ---
>  drivers/gpu/drm/drm_atomic_helper.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> index ddfa0d1..939df90 100644
> --- a/drivers/gpu/drm/drm_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> @@ -414,6 +414,9 @@ mode_fixup(struct drm_atomic_state *state)
>  	for_each_crtc_in_state(state, crtc, crtc_state, i) {
>  		const struct drm_crtc_helper_funcs *funcs;
>  
> +		if (!crtc_state->enable)
> +			continue;
> +
>  		if (!crtc_state->mode_changed &&
>  		    !crtc_state->connectors_changed)
>  			continue;
> -- 
> 2.7.4
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch