Hi! Dne sobota, 28. december 2019 ob 21:28:15 CET je roman.stratiienko@xxxxxxxxxxxxxxx napisal(a): > From: Roman Stratiienko <roman.stratiienko@xxxxxxxxxxxxxxx> > > Screen composition that requires dynamic layout modification, > especially scaling is corrupted when layout changes. > > For example if one of the layer scales down, misaligned lines can be > observed, and dynamic increasing of destination area makes mixer to hang > and draw nothing after drawing modified layer. > > After deep investigation it turns that scaler double-buffered registers > are not latched by GLB_DBUFFER bit, instead thay are latched immidiately. > > Only way to avoid artifacts is to change the registers after mixer finish > previous frame. > > Similar was made in sunxi BSP - scaler register values was stored into RAM, > and moved into registers at sync together with GLB_DBUFFER. > > Signed-off-by: Roman Stratiienko <roman.stratiienko@xxxxxxxxxxxxxxx> Nice catch! However, I'm a bit worried about blocking nature of this solution. What about shadowing scaler registers and applying them in "finish_irq" handler? You see, VI scaler can in some cases consume almost all time between two VSync events. That issue came up on A64 mixer1 with downscaling 4K videos in real time. I imagine that this solution might block for too long in this case. Check VI coarse scaling code: https://elixir.bootlin.com/linux/v5.5-rc3/source/drivers/gpu/drm/sun4i/ sun8i_vi_layer.c#L144 > --- > drivers/gpu/drm/sun4i/sun8i_mixer.c | 15 +++++++++++++++ > drivers/gpu/drm/sun4i/sun8i_mixer.h | 2 ++ > 2 files changed, 17 insertions(+) > > diff --git a/drivers/gpu/drm/sun4i/sun8i_mixer.c > b/drivers/gpu/drm/sun4i/sun8i_mixer.c index 8b803eb903b8..eea4813602b7 > 100644 > --- a/drivers/gpu/drm/sun4i/sun8i_mixer.c > +++ b/drivers/gpu/drm/sun4i/sun8i_mixer.c > @@ -257,6 +257,20 @@ const struct de2_fmt_info *sun8i_mixer_format_info(u32 > format) return NULL; > } > > +static void sun8i_atomic_begin(struct sunxi_engine *engine, > + struct drm_crtc_state *old_state) > +{ > + int reg, ret; > + > + ret = regmap_read_poll_timeout(engine->regs, SUN8I_MIXER_GLOBAL_STATUS, > + reg, > + !(reg & SUN8I_MIXER_GLOBAL_STATUS_BUSY), > + 200, 100000); > + > + if (ret) > + pr_warn("%s: Wait for frame finish timeout\n", __func__); Newly introduced drm_warn() should be used here. Best regards, Jernej > +} > + > static void sun8i_mixer_commit(struct sunxi_engine *engine) > { > DRM_DEBUG_DRIVER("Committing changes\n"); > @@ -310,6 +324,7 @@ static struct drm_plane **sun8i_layers_init(struct > drm_device *drm, static const struct sunxi_engine_ops sun8i_engine_ops = { > .commit = sun8i_mixer_commit, > .layers_init = sun8i_layers_init, > + .atomic_begin = sun8i_atomic_begin, > }; > > static struct regmap_config sun8i_mixer_regmap_config = { > diff --git a/drivers/gpu/drm/sun4i/sun8i_mixer.h > b/drivers/gpu/drm/sun4i/sun8i_mixer.h index c6cc94057faf..915479cc3077 > 100644 > --- a/drivers/gpu/drm/sun4i/sun8i_mixer.h > +++ b/drivers/gpu/drm/sun4i/sun8i_mixer.h > @@ -25,6 +25,8 @@ > > #define SUN8I_MIXER_GLOBAL_DBUFF_ENABLE BIT(0) > > +#define SUN8I_MIXER_GLOBAL_STATUS_BUSY BIT(4) > + > #define DE2_MIXER_UNIT_SIZE 0x6000 > #define DE3_MIXER_UNIT_SIZE 0x3000 _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
