[PATCH v15 3/5] drm: renesas: Add RZ/G2L DU Support

[Biju Das]

> Subject: RE: [PATCH v15 3/5] drm: renesas: Add RZ/G2L DU Support
> 
> Hi Maxime Ripard,
> 
> > -----Original Message-----
> > From: Maxime Ripard <mripard at kernel.org>
> > Sent: Friday, December 15, 2023 2:18 PM
> > Subject: Re: [PATCH v15 3/5] drm: renesas: Add RZ/G2L DU Support
> >
> > On Fri, Dec 15, 2023 at 01:52:28PM +0000, Biju Das wrote:
> > > > > > > > > +static int rzg2l_du_crtc_enable_vblank(struct drm_crtc
> > *crtc) {
> > > > > > > > > +	struct rzg2l_du_crtc *rcrtc = to_rzg2l_crtc(crtc);
> > > > > > > > > +
> > > > > > > > > +	rcrtc->vblank_enable = true;
> > > > > > > > > +
> > > > > > > > > +	return 0;
> > > > > > > > > +}
> > > > > > > > > +
> > > > > > > > > +static void rzg2l_du_crtc_disable_vblank(struct
> > > > > > > > > +drm_crtc
> > > > > > > > > +*crtc)
> > > > {
> > > > > > > > > +	struct rzg2l_du_crtc *rcrtc = to_rzg2l_crtc(crtc);
> > > > > > > > > +
> > > > > > > > > +	rcrtc->vblank_enable = false; }
> > > > > > > >
> > > > > > > > You should enable / disable your interrupts here
> > > > > > >
> > > > > > > We don't have dedicated vblank IRQ for enabling/disabling
> > vblank.
> > > > > > >
> > > > > > > vblank is handled by vspd.
> > > > > > >
> > > > > > > vspd is directly rendering images to display,
> > > > > > > rcar_du_crtc_finish_page_flip() and drm_crtc_handle_vblank()
> > > > > > > called in vspd's pageflip context.
> > > > > > >
> > > > > > > See rzg2l_du_vsp_complete()in rzg2l_du_vsp.c
> > > > > >
> > > > > > Sorry, I couldn't really get how the interrupt flow / vblank
> > > > > > reporting is going to work. Could you explain it a bit more?
> > > > >
> > > > > We just need to handle vertical blanking in the VSP frame end
> > handler.
> > > > > See the code below.
> > > > >
> > > > > static void rzg2l_du_vsp_complete(void *private, unsigned int
> > > > > status,
> > > > > u32 crc) {
> > > > > 	struct rzg2l_du_crtc *crtc = private;
> > > > >
> > > > > 	if (crtc->vblank_enable)
> > > > > 		drm_crtc_handle_vblank(&crtc->crtc);
> > > > >
> > > > > 	if (status & VSP1_DU_STATUS_COMPLETE)
> > > > > 		rzg2l_du_crtc_finish_page_flip(crtc);
> > > > >
> > > > > 	drm_crtc_add_crc_entry(&crtc->crtc, false, 0, &crc); }
> > > >
> > > > Then we're back to the same question :)
> > > >
> > > > Why can't you mask the frame end interrupt?
> > >
> > > We are masking interrupts.
> > >
> > > [   70.639139] #######rzg2l_du_crtc_disable_vblank#######
> > > [   70.650243] #########rzg2l_du_vsp_disable ############
> > > [   70.652003] ########## vsp1_wpf_stop###
> > >
> > > Unmask is,
> > >
> > > [ 176.354520] #######rzg2l_du_crtc_enable_vblank#######
> > > [  176.354922] #########rzg2l_du_vsp_atomic_flush ############ [
> > > 176.355198] ########## wpf_configure_stream###
> >
> > Sorry, my question was why aren't you unmasking and masking them in
> > the enable/disable_vblank hooks of the CRTC.
> 
> I have n't tried that. Will try and provide feedback.
> 
> Currently the IRQ source belongs to VSPD in media subsystem.
> So I need to export an API though vsp1_drm and test it.
> 
> 
> Currently we disable IRQ in rzg2l_du_crtc_atomic_disable() context
> 
> And enable IRQ in rzg2l_du_vsp_atomic_flush().


Typo, it is rzg2l_du_crtc_atomic_flush().

Cheers,
Biju