On Thu, May 05, 2016 at 05:13:38PM +0100, Robin Murphy wrote:
> The current PM ops simply unconditionally enable/disable the HDLCD,
> which proves problematic when there is no display plugged in - since
> without a crtc the hardware itself is still in an uninitialised state,
> coming out of suspend results in it being enabled without a valid
> framebuffer address, which typically results in it trying to scan out
> from bus address 0 and flooding the system with error interrupts.
>
> Fix this by checking the crtc state on resume, and only enabling the
> hardware if it's actually supposed to be. For the sake of consistency,
> do the same on the suspend path as well, although there it's merely a
> case of skipping unnecessary work.
>
> CC: Liviu Dudau <liviu.dudau@xxxxxxx>
> Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
> ---
> drivers/gpu/drm/arm/hdlcd_crtc.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/arm/hdlcd_crtc.c b/drivers/gpu/drm/arm/hdlcd_crtc.c
> index fef1b04c2aab..bf6ff5e48adc 100644
> --- a/drivers/gpu/drm/arm/hdlcd_crtc.c
> +++ b/drivers/gpu/drm/arm/hdlcd_crtc.c
> @@ -296,12 +296,14 @@ static struct drm_plane *hdlcd_plane_init(struct drm_device *drm)
>
> void hdlcd_crtc_suspend(struct drm_crtc *crtc)
> {
> - hdlcd_crtc_disable(crtc);
> + if (crtc->state->active)
> + hdlcd_crtc_disable(crtc);
> }
>
> void hdlcd_crtc_resume(struct drm_crtc *crtc)
> {
> - hdlcd_crtc_enable(crtc);
> + if (crtc->state->active)
> + hdlcd_crtc_enable(crtc);
> }
If you use the atomic helpers to suspend/resume your entire display
pipeline these callbacks shouldn't even be needed at all. Tried just
removing them?
-Daniel
>
> int hdlcd_setup_crtc(struct drm_device *drm)
> --
> 2.8.1.dirty
>
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--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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