| Message ID | 7371f62a1385f2cbe3ed75dfca2e746338eb2286.1516617243.git-series.maxime.ripard@free-electrons.com |
|---|---|
| State | Accepted |
| Commit | 65f7fa3a3fcbdb67940a58ce24516d62aaec12b7 |
| Headers | show |
| Series | None | expand |
On Mon, Jan 22, 2018 at 6:35 PM, Maxime Ripard <maxime.ripard@free-electrons.com> wrote: > Due to the way the composition is done in hardware, we can only have a > single alpha-enabled plane active at a time, placed in the second (highest > priority) pipe. > > Make sure of that in our atomic_check to not end up in an impossible > scenario. > > Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com> > --- > drivers/gpu/drm/sun4i/sun4i_backend.c | 50 ++++++++++++++++++++++++++++- > drivers/gpu/drm/sun4i/sun4i_backend.h | 2 +- > drivers/gpu/drm/sun4i/sun4i_layer.c | 23 +------------- > 3 files changed, 53 insertions(+), 22 deletions(-) > > diff --git a/drivers/gpu/drm/sun4i/sun4i_backend.c b/drivers/gpu/drm/sun4i/sun4i_backend.c > index c4986054909b..eb1749d2c0d5 100644 > --- a/drivers/gpu/drm/sun4i/sun4i_backend.c > +++ b/drivers/gpu/drm/sun4i/sun4i_backend.c > @@ -329,6 +329,8 @@ static int sun4i_backend_atomic_check(struct sunxi_engine *engine, > struct drm_atomic_state *state = crtc_state->state; > struct drm_device *drm = state->dev; > struct drm_plane *plane; > + unsigned int num_planes = 0; > + unsigned int num_alpha_planes = 0; > unsigned int num_frontend_planes = 0; > > DRM_DEBUG_DRIVER("Starting checking our planes\n"); > @@ -341,6 +343,7 @@ static int sun4i_backend_atomic_check(struct sunxi_engine *engine, > drm_atomic_get_plane_state(state, plane); > struct sun4i_layer_state *layer_state = > state_to_sun4i_layer_state(plane_state); > + struct drm_framebuffer *fb = plane_state->fb; > > if (sun4i_backend_plane_uses_frontend(plane_state)) { > DRM_DEBUG_DRIVER("Using the frontend for plane %d\n", > @@ -351,6 +354,50 @@ static int sun4i_backend_atomic_check(struct sunxi_engine *engine, > } else { > layer_state->uses_frontend = false; > } > + > + DRM_DEBUG_DRIVER("Plane FB format is %s\n", > + drm_get_format_name(fb->format->format, > + &format_name)); > + if (fb->format->has_alpha) > + num_alpha_planes++; > + > + num_planes++; > + } > + > + /* > + * The hardware is a bit unusual here. > + * > + * Even though it supports 4 layers, it does the composition > + * in two separate steps. > + * > + * The first one is assigning a layer to one of its two > + * pipes. If more that 1 layer is assigned to the same pipe, > + * and if pixels overlaps, the pipe will take the pixel from > + * the layer with the highest priority. > + * > + * The second step is the actual alpha blending, that takes > + * the two pipes as input, and uses the eventual alpha > + * component to do the transparency between the two. > + * > + * This two steps scenario makes us unable to guarantee a > + * robust alpha blending between the 4 layers in all > + * situations, since this means that we need to have one layer > + * with alpha at the lowest position of our two pipes. > + * > + * However, we cannot even do that, since the hardware has a > + * bug where the lowest plane of the lowest pipe (pipe 0, > + * priority 0), if it has any alpha, will discard the pixel > + * entirely and just display the pixels in the background > + * color (black by default). > + * > + * Since means that we effectively have only three valid ^^^^^ This > + * configurations with alpha, all of them with the alpha being > + * on pipe1 with the lowest position, which can be 1, 2 or 3 > + * depending on the number of planes and their zpos. > + */ > + if (num_alpha_planes > SUN4I_BACKEND_NUM_ALPHA_LAYERS) { > + DRM_DEBUG_DRIVER("Too many planes with alpha, rejecting...\n"); > + return -EINVAL; > } > > if (num_frontend_planes > SUN4I_BACKEND_NUM_FRONTEND_LAYERS) { > @@ -358,6 +405,9 @@ static int sun4i_backend_atomic_check(struct sunxi_engine *engine, > return -EINVAL; > } > > + DRM_DEBUG_DRIVER("State valid with %u planes, %u alpha, %u video\n", > + num_planes, num_alpha_planes, num_frontend_planes); > + > return 0; > } > > diff --git a/drivers/gpu/drm/sun4i/sun4i_backend.h b/drivers/gpu/drm/sun4i/sun4i_backend.h > index 04a4f11b87a8..52e77591186a 100644 > --- a/drivers/gpu/drm/sun4i/sun4i_backend.h > +++ b/drivers/gpu/drm/sun4i/sun4i_backend.h > @@ -146,6 +146,8 @@ > #define SUN4I_BACKEND_HWCCOLORTAB_OFF 0x4c00 > #define SUN4I_BACKEND_PIPE_OFF(p) (0x5000 + (0x400 * (p))) > > +#define SUN4I_BACKEND_NUM_LAYERS 4 > +#define SUN4I_BACKEND_NUM_ALPHA_LAYERS 1 > #define SUN4I_BACKEND_NUM_FRONTEND_LAYERS 1 > > struct sun4i_backend { > diff --git a/drivers/gpu/drm/sun4i/sun4i_layer.c b/drivers/gpu/drm/sun4i/sun4i_layer.c > index fbf25d59cf88..900e716443b8 100644 > --- a/drivers/gpu/drm/sun4i/sun4i_layer.c > +++ b/drivers/gpu/drm/sun4i/sun4i_layer.c > @@ -201,32 +201,11 @@ struct drm_plane **sun4i_layers_init(struct drm_device *drm, > struct sun4i_backend *backend = engine_to_sun4i_backend(engine); > int i; > > - planes = devm_kcalloc(drm->dev, ARRAY_SIZE(sun4i_backend_planes) + 1, > + planes = devm_kcalloc(drm->dev, SUN4I_BACKEND_NUM_LAYERS, > sizeof(*planes), GFP_KERNEL); The returned "planes" array has to have a sentinel at the end, as we never return the actual number of layers created. That is what the +1 was for in the original code. Otherwise, Reviewed-by: Chen-Yu Tsai <wens@csie.org> > if (!planes) > return ERR_PTR(-ENOMEM); > > - /* > - * The hardware is a bit unusual here. > - * > - * Even though it supports 4 layers, it does the composition > - * in two separate steps. > - * > - * The first one is assigning a layer to one of its two > - * pipes. If more that 1 layer is assigned to the same pipe, > - * and if pixels overlaps, the pipe will take the pixel from > - * the layer with the highest priority. > - * > - * The second step is the actual alpha blending, that takes > - * the two pipes as input, and uses the eventual alpha > - * component to do the transparency between the two. > - * > - * This two steps scenario makes us unable to guarantee a > - * robust alpha blending between the 4 layers in all > - * situations. So we just expose two layers, one per pipe. On > - * SoCs that support it, sprites could fill the need for more > - * layers. > - */ > for (i = 0; i < ARRAY_SIZE(sun4i_backend_planes); i++) { > const struct sun4i_plane_desc *plane = &sun4i_backend_planes[i]; > struct sun4i_layer *layer; > -- > git-series 0.9.1
diff --git a/drivers/gpu/drm/sun4i/sun4i_backend.c b/drivers/gpu/drm/sun4i/sun4i_backend.c index c4986054909b..eb1749d2c0d5 100644 --- a/drivers/gpu/drm/sun4i/sun4i_backend.c +++ b/drivers/gpu/drm/sun4i/sun4i_backend.c @@ -329,6 +329,8 @@ static int sun4i_backend_atomic_check(struct sunxi_engine *engine, struct drm_atomic_state *state = crtc_state->state; struct drm_device *drm = state->dev; struct drm_plane *plane; + unsigned int num_planes = 0; + unsigned int num_alpha_planes = 0; unsigned int num_frontend_planes = 0; DRM_DEBUG_DRIVER("Starting checking our planes\n"); @@ -341,6 +343,7 @@ static int sun4i_backend_atomic_check(struct sunxi_engine *engine, drm_atomic_get_plane_state(state, plane); struct sun4i_layer_state *layer_state = state_to_sun4i_layer_state(plane_state); + struct drm_framebuffer *fb = plane_state->fb; if (sun4i_backend_plane_uses_frontend(plane_state)) { DRM_DEBUG_DRIVER("Using the frontend for plane %d\n", @@ -351,6 +354,50 @@ static int sun4i_backend_atomic_check(struct sunxi_engine *engine, } else { layer_state->uses_frontend = false; } + + DRM_DEBUG_DRIVER("Plane FB format is %s\n", + drm_get_format_name(fb->format->format, + &format_name)); + if (fb->format->has_alpha) + num_alpha_planes++; + + num_planes++; + } + + /* + * The hardware is a bit unusual here. + * + * Even though it supports 4 layers, it does the composition + * in two separate steps. + * + * The first one is assigning a layer to one of its two + * pipes. If more that 1 layer is assigned to the same pipe, + * and if pixels overlaps, the pipe will take the pixel from + * the layer with the highest priority. + * + * The second step is the actual alpha blending, that takes + * the two pipes as input, and uses the eventual alpha + * component to do the transparency between the two. + * + * This two steps scenario makes us unable to guarantee a + * robust alpha blending between the 4 layers in all + * situations, since this means that we need to have one layer + * with alpha at the lowest position of our two pipes. + * + * However, we cannot even do that, since the hardware has a + * bug where the lowest plane of the lowest pipe (pipe 0, + * priority 0), if it has any alpha, will discard the pixel + * entirely and just display the pixels in the background + * color (black by default). + * + * Since means that we effectively have only three valid + * configurations with alpha, all of them with the alpha being + * on pipe1 with the lowest position, which can be 1, 2 or 3 + * depending on the number of planes and their zpos. + */ + if (num_alpha_planes > SUN4I_BACKEND_NUM_ALPHA_LAYERS) { + DRM_DEBUG_DRIVER("Too many planes with alpha, rejecting...\n"); + return -EINVAL; } if (num_frontend_planes > SUN4I_BACKEND_NUM_FRONTEND_LAYERS) { @@ -358,6 +405,9 @@ static int sun4i_backend_atomic_check(struct sunxi_engine *engine, return -EINVAL; } + DRM_DEBUG_DRIVER("State valid with %u planes, %u alpha, %u video\n", + num_planes, num_alpha_planes, num_frontend_planes); + return 0; } diff --git a/drivers/gpu/drm/sun4i/sun4i_backend.h b/drivers/gpu/drm/sun4i/sun4i_backend.h index 04a4f11b87a8..52e77591186a 100644 --- a/drivers/gpu/drm/sun4i/sun4i_backend.h +++ b/drivers/gpu/drm/sun4i/sun4i_backend.h @@ -146,6 +146,8 @@ #define SUN4I_BACKEND_HWCCOLORTAB_OFF 0x4c00 #define SUN4I_BACKEND_PIPE_OFF(p) (0x5000 + (0x400 * (p))) +#define SUN4I_BACKEND_NUM_LAYERS 4 +#define SUN4I_BACKEND_NUM_ALPHA_LAYERS 1 #define SUN4I_BACKEND_NUM_FRONTEND_LAYERS 1 struct sun4i_backend { diff --git a/drivers/gpu/drm/sun4i/sun4i_layer.c b/drivers/gpu/drm/sun4i/sun4i_layer.c index fbf25d59cf88..900e716443b8 100644 --- a/drivers/gpu/drm/sun4i/sun4i_layer.c +++ b/drivers/gpu/drm/sun4i/sun4i_layer.c @@ -201,32 +201,11 @@ struct drm_plane **sun4i_layers_init(struct drm_device *drm, struct sun4i_backend *backend = engine_to_sun4i_backend(engine); int i; - planes = devm_kcalloc(drm->dev, ARRAY_SIZE(sun4i_backend_planes) + 1, + planes = devm_kcalloc(drm->dev, SUN4I_BACKEND_NUM_LAYERS, sizeof(*planes), GFP_KERNEL); if (!planes) return ERR_PTR(-ENOMEM); - /* - * The hardware is a bit unusual here. - * - * Even though it supports 4 layers, it does the composition - * in two separate steps. - * - * The first one is assigning a layer to one of its two - * pipes. If more that 1 layer is assigned to the same pipe, - * and if pixels overlaps, the pipe will take the pixel from - * the layer with the highest priority. - * - * The second step is the actual alpha blending, that takes - * the two pipes as input, and uses the eventual alpha - * component to do the transparency between the two. - * - * This two steps scenario makes us unable to guarantee a - * robust alpha blending between the 4 layers in all - * situations. So we just expose two layers, one per pipe. On - * SoCs that support it, sprites could fill the need for more - * layers. - */ for (i = 0; i < ARRAY_SIZE(sun4i_backend_planes); i++) { const struct sun4i_plane_desc *plane = &sun4i_backend_planes[i]; struct sun4i_layer *layer;
Due to the way the composition is done in hardware, we can only have a single alpha-enabled plane active at a time, placed in the second (highest priority) pipe. Make sure of that in our atomic_check to not end up in an impossible scenario. Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com> --- drivers/gpu/drm/sun4i/sun4i_backend.c | 50 ++++++++++++++++++++++++++++- drivers/gpu/drm/sun4i/sun4i_backend.h | 2 +- drivers/gpu/drm/sun4i/sun4i_layer.c | 23 +------------- 3 files changed, 53 insertions(+), 22 deletions(-) -- git-series 0.9.1