| Message ID | 20201105135656.383350-6-maxime@cerno.tech |
|---|---|
| State | Accepted |
| Commit | b5dbc4d36885bef6257054a737a76101d293b185 |
| Headers | show |
| Series | drm/vc4: Rework the HVS muxing code | expand |
Hi Thomas, Thanks again for your review On Thu, Nov 19, 2020 at 09:11:58AM +0100, Thomas Zimmermann wrote: > Hi, > > A few suggestions below. But I'm not a native speaker. > > Am 05.11.20 um 14:56 schrieb Maxime Ripard: > > We've had a number of muxing corner-cases with specific ways to reproduce > > them, so let's document them to make sure they aren't lost and introduce > > regressions later on. > > > > Reviewed-by: Hoegeun Kwon <hoegeun.kwon@samsung.com> > > Tested-by: Hoegeun Kwon <hoegeun.kwon@samsung.com> > > Signed-off-by: Maxime Ripard <maxime@cerno.tech> > > --- > > drivers/gpu/drm/vc4/vc4_kms.c | 22 ++++++++++++++++++++++ > > 1 file changed, 22 insertions(+) > > > > diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c > > index bb2efc5d2d01..499c6914fce4 100644 > > --- a/drivers/gpu/drm/vc4/vc4_kms.c > > +++ b/drivers/gpu/drm/vc4/vc4_kms.c > > @@ -662,6 +662,28 @@ static int vc4_load_tracker_obj_init(struct vc4_dev *vc4) > > return drmm_add_action_or_reset(&vc4->base, vc4_load_tracker_obj_fini, NULL); > > } > > +/* > > + * The BCM2711 HVS has up to 7 output connected to the pixelvalves and > > '7 outputs' > > Is it 'pixelvalves' or 'pixel valves'? The documentation uses both, but the driver uses the former all the time. > > > + * the TXP (and therefore all the CRTCs found on that platform). > > + * > > + * The naive (and our initial) implementation would just iterate over > > + * all the active CRTCs, try to find a suitable FIFO, and then remove it > > + * from the available FIFOs pool. However, there's a few corner cases > > I'd write. 'and remove it from the pool of available FIFOs'. Sounds more > natural to me. > > 'there are a few' > > > + * that need to be considered: > > + * > > + * - When running in a dual-display setup (so with two CRTCs involved), > > + * we can update the state of a single CRTC (for example by changing > > + * its mode using xrandr under X11) without affecting the other. In > > + * this case, the other CRTC wouldn't be in the state at all, so we > > + * need to consider all the running CRTCs in the DRM device to assign > > + * a FIFO, not just the one in the state. > > + * > > + * - Since we need the pixelvalve to be disabled and enabled back when > > + * the FIFO is changed, we should keep the FIFO assigned for as long > > + * as the CRTC is enabled, only considering it free again once that > > + * CRTC has been disabled. This can be tested by booting X11 on a > > + * single display, and changing the resolution down and then back up. > > + */ > > With my suggestions considered, > > Acked-by: Thomas Zimmermann <tzimmermann@suse.de> I've applied it with your comments fixed. Thanks! Maxime
diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c index bb2efc5d2d01..499c6914fce4 100644 --- a/drivers/gpu/drm/vc4/vc4_kms.c +++ b/drivers/gpu/drm/vc4/vc4_kms.c @@ -662,6 +662,28 @@ static int vc4_load_tracker_obj_init(struct vc4_dev *vc4) return drmm_add_action_or_reset(&vc4->base, vc4_load_tracker_obj_fini, NULL); } +/* + * The BCM2711 HVS has up to 7 output connected to the pixelvalves and + * the TXP (and therefore all the CRTCs found on that platform). + * + * The naive (and our initial) implementation would just iterate over + * all the active CRTCs, try to find a suitable FIFO, and then remove it + * from the available FIFOs pool. However, there's a few corner cases + * that need to be considered: + * + * - When running in a dual-display setup (so with two CRTCs involved), + * we can update the state of a single CRTC (for example by changing + * its mode using xrandr under X11) without affecting the other. In + * this case, the other CRTC wouldn't be in the state at all, so we + * need to consider all the running CRTCs in the DRM device to assign + * a FIFO, not just the one in the state. + * + * - Since we need the pixelvalve to be disabled and enabled back when + * the FIFO is changed, we should keep the FIFO assigned for as long + * as the CRTC is enabled, only considering it free again once that + * CRTC has been disabled. This can be tested by booting X11 on a + * single display, and changing the resolution down and then back up. + */ static int vc4_pv_muxing_atomic_check(struct drm_device *dev, struct drm_atomic_state *state) {