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Date: Thu, 5 May 2016 19:01:17 +0100 From: Robin Murphy <robin.murphy@....com> To: airlied@...ux.ie, liviu.dudau@....com, dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org Subject: Re: [PATCH 2/2] drm: hdlcd: Suspend/resume only active crtcs Hi Daniel, On 05/05/16 18:06, Daniel Vetter wrote: > 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@....com> >> Signed-off-by: Robin Murphy <robin.murphy@....com> >> --- >> 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? I'll have to leave that in Liviu's hands as I know literally nothing about the relationship between platform PM ops and DRM helpers ;) My only motivation is for the arm64 hibernate support currently sat in -next for 4.7 to stop being broken on my Juno board by this. Robin. > -Daniel > >> >> int hdlcd_setup_crtc(struct drm_device *drm) >> -- >> 2.8.1.dirty >> >> _______________________________________________ >> dri-devel mailing list >> dri-devel@...ts.freedesktop.org >> https://lists.freedesktop.org/mailman/listinfo/dri-devel >
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