From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= Subject: Re: [PATCH v3 3/4] drm/vblank: estimate vblank while disabling vblank if interrupt disabled Date: Wed, 26 Jun 2019 16:27:32 +0300 Message-ID: <20190626132732.GP5942@intel.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Robert Beckett Cc: dri-devel@lists.freedesktop.org, Maxime Ripard , Shawn Guo , linux-kernel@vger.kernel.org, David Airlie , NXP Linux Team , Sean Paul , Pengutronix Kernel Team , linux-arm-kernel@lists.infradead.org List-Id: dri-devel@lists.freedesktop.org On Tue, Jun 25, 2019 at 06:59:14PM +0100, Robert Beckett wrote: > If interrupts are disabled (e.g. via vblank_disable_fn) and we come to > disable vblank, update the vblank count to best guess as to what it > would be had the interrupts remained enabled, and update the timesamp to > now. > > This avoids a stale vblank event being sent while disabling crtcs during > atomic modeset. > > Fixes: 68036b08b91bc ("drm/vblank: Do not update vblank count if interrupts > are already disabled.") I don't understand that commit. drm_vblank_off() should be called when the power is still present, so it looks to me like that commit is actually wrong. So I think we may want to just revert it and figure out what the actual bug was. > > Signed-off-by: Robert Beckett > --- > drivers/gpu/drm/drm_vblank.c | 16 +++++++++++++++- > 1 file changed, 15 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c > index 7dabb2bdb733..db68b8cbf797 100644 > --- a/drivers/gpu/drm/drm_vblank.c > +++ b/drivers/gpu/drm/drm_vblank.c > @@ -375,9 +375,23 @@ void drm_vblank_disable_and_save(struct drm_device *dev, unsigned int pipe) > * interrupts were enabled. This avoids calling the ->disable_vblank() > * operation in atomic context with the hardware potentially runtime > * suspended. > + * If interrupts are disabled (e.g. via blank_disable_fn) then make > + * best guess as to what it would be now and make sure we have an up > + * to date timestamp. > */ > - if (!vblank->enabled) > + if (!vblank->enabled) { > + ktime_t now = ktime_get(); > + u32 diff = 0; > + if (vblank->framedur_ns) { > + u64 diff_ns = ktime_to_ns(ktime_sub(now, vblank->time)); > + diff = DIV_ROUND_CLOSEST_ULL(diff_ns, > + vblank->framedur_ns); > + } > + > + store_vblank(dev, pipe, diff, now, vblank->count); > + > goto out; > + } > > /* > * Update the count and timestamp to maintain the > -- > 2.18.0 > > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- Ville Syrjälä Intel