Hi Am 22.11.22 um 21:58 schrieb Noralf Trønnes via B4 Submission Endpoint:
From: Noralf Trønnes <noralf@xxxxxxxxxxx> Use the shadow plane helper to take care of preparing the framebuffer for CPU access. The synchronous flushing is now done inline without the use of a worker. The async path now uses a shadow buffer to hold framebuffer changes and it doesn't read the framebuffer behind userspace's back anymore. Signed-off-by: Noralf Trønnes <noralf@xxxxxxxxxxx> --- drivers/gpu/drm/gud/gud_drv.c | 1 + drivers/gpu/drm/gud/gud_internal.h | 1 + drivers/gpu/drm/gud/gud_pipe.c | 69 ++++++++++++++++++++++++-------------- 3 files changed, 46 insertions(+), 25 deletions(-) diff --git a/drivers/gpu/drm/gud/gud_drv.c b/drivers/gpu/drm/gud/gud_drv.c index d57dab104358..5aac7cda0505 100644 --- a/drivers/gpu/drm/gud/gud_drv.c +++ b/drivers/gpu/drm/gud/gud_drv.c @@ -365,6 +365,7 @@ static void gud_debugfs_init(struct drm_minor *minor) static const struct drm_simple_display_pipe_funcs gud_pipe_funcs = { .check = gud_pipe_check, .update = gud_pipe_update, + DRM_GEM_SIMPLE_DISPLAY_PIPE_SHADOW_PLANE_FUNCS };static const struct drm_mode_config_funcs gud_mode_config_funcs = {diff --git a/drivers/gpu/drm/gud/gud_internal.h b/drivers/gpu/drm/gud/gud_internal.h index e351a1f1420d..0d148a6f27aa 100644 --- a/drivers/gpu/drm/gud/gud_internal.h +++ b/drivers/gpu/drm/gud/gud_internal.h @@ -43,6 +43,7 @@ struct gud_device { struct drm_framebuffer *fb; struct drm_rect damage; bool prev_flush_failed; + void *shadow_buf; };static inline struct gud_device *to_gud_device(struct drm_device *drm)diff --git a/drivers/gpu/drm/gud/gud_pipe.c b/drivers/gpu/drm/gud/gud_pipe.c index dfada6eedc58..7686325f7ee7 100644 --- a/drivers/gpu/drm/gud/gud_pipe.c +++ b/drivers/gpu/drm/gud/gud_pipe.c @@ -358,10 +358,10 @@ static void gud_flush_damage(struct gud_device *gdrm, struct drm_framebuffer *fb void gud_flush_work(struct work_struct *work) { struct gud_device *gdrm = container_of(work, struct gud_device, work); - struct iosys_map gem_map = { }, fb_map = { }; + struct iosys_map shadow_map; struct drm_framebuffer *fb; struct drm_rect damage; - int idx, ret; + int idx;if (!drm_dev_enter(&gdrm->drm, &idx))return; @@ -369,6 +369,7 @@ void gud_flush_work(struct work_struct *work) mutex_lock(&gdrm->damage_lock); fb = gdrm->fb; gdrm->fb = NULL; + iosys_map_set_vaddr(&shadow_map, gdrm->shadow_buf); damage = gdrm->damage; gud_clear_damage(gdrm); mutex_unlock(&gdrm->damage_lock); @@ -376,33 +377,33 @@ void gud_flush_work(struct work_struct *work) if (!fb) goto out;- ret = drm_gem_fb_vmap(fb, &gem_map, &fb_map);- if (ret) - goto fb_put; + gud_flush_damage(gdrm, fb, &shadow_map, true, &damage);- ret = drm_gem_fb_begin_cpu_access(fb, DMA_FROM_DEVICE);- if (ret) - goto vunmap; - - /* Imported buffers are assumed to be WriteCombined with uncached reads */ - gud_flush_damage(gdrm, fb, &fb_map, !fb->obj[0]->import_attach, &damage); - - drm_gem_fb_end_cpu_access(fb, DMA_FROM_DEVICE); -vunmap: - drm_gem_fb_vunmap(fb, &gem_map); -fb_put: drm_framebuffer_put(fb); out: drm_dev_exit(idx); }-static void gud_fb_queue_damage(struct gud_device *gdrm, struct drm_framebuffer *fb,- struct drm_rect *damage) +static int gud_fb_queue_damage(struct gud_device *gdrm, struct drm_framebuffer *fb, + const struct iosys_map *map, struct drm_rect *damage) { struct drm_framebuffer *old_fb = NULL; + struct iosys_map shadow_map;mutex_lock(&gdrm->damage_lock); + if (!gdrm->shadow_buf) {+ gdrm->shadow_buf = vzalloc(fb->pitches[0] * fb->height); + if (!gdrm->shadow_buf) { + mutex_unlock(&gdrm->damage_lock); + return -ENOMEM; + } + } + + iosys_map_set_vaddr(&shadow_map, gdrm->shadow_buf); + iosys_map_incr(&shadow_map, drm_fb_clip_offset(fb->pitches[0], fb->format, damage)); + drm_fb_memcpy(&shadow_map, fb->pitches, map, fb, damage); +
It's all good (sans the begin_cpu_access issue) in terms of code, but the memcpy here can have quite an impact on performace.
So why not just nuke the async code entirely? It's a userspace problem and we don't have many(/any?) other drivers with such a workaround. Udl, our other usb-based driver, works well enough without.
Best regards Thomas
if (fb != gdrm->fb) { old_fb = gdrm->fb; drm_framebuffer_get(fb); @@ -420,6 +421,26 @@ static void gud_fb_queue_damage(struct gud_device *gdrm, struct drm_framebufferif (old_fb)drm_framebuffer_put(old_fb); + + return 0; +} + +static void gud_fb_handle_damage(struct gud_device *gdrm, struct drm_framebuffer *fb, + const struct iosys_map *map, struct drm_rect *damage) +{ + int ret; + + if (gdrm->flags & GUD_DISPLAY_FLAG_FULL_UPDATE) + drm_rect_init(damage, 0, 0, fb->width, fb->height); + + if (gud_async_flush) { + ret = gud_fb_queue_damage(gdrm, fb, map, damage); + if (ret != -ENOMEM) + return; + } + + /* Imported buffers are assumed to be WriteCombined with uncached reads */ + gud_flush_damage(gdrm, fb, map, !fb->obj[0]->import_attach, damage); }int gud_pipe_check(struct drm_simple_display_pipe *pipe,@@ -544,6 +565,7 @@ void gud_pipe_update(struct drm_simple_display_pipe *pipe, struct drm_device *drm = pipe->crtc.dev; struct gud_device *gdrm = to_gud_device(drm); struct drm_plane_state *state = pipe->plane.state; + struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(state); struct drm_framebuffer *fb = state->fb; struct drm_crtc *crtc = &pipe->crtc; struct drm_rect damage; @@ -557,6 +579,8 @@ void gud_pipe_update(struct drm_simple_display_pipe *pipe, gdrm->fb = NULL; } gud_clear_damage(gdrm); + vfree(gdrm->shadow_buf); + gdrm->shadow_buf = NULL; mutex_unlock(&gdrm->damage_lock); }@@ -572,13 +596,8 @@ void gud_pipe_update(struct drm_simple_display_pipe *pipe,if (crtc->state->active_changed) gud_usb_set_u8(gdrm, GUD_REQ_SET_DISPLAY_ENABLE, crtc->state->active);- if (drm_atomic_helper_damage_merged(old_state, state, &damage)) {- if (gdrm->flags & GUD_DISPLAY_FLAG_FULL_UPDATE) - drm_rect_init(&damage, 0, 0, fb->width, fb->height); - gud_fb_queue_damage(gdrm, fb, &damage); - if (!gud_async_flush) - flush_work(&gdrm->work); - } + if (drm_atomic_helper_damage_merged(old_state, state, &damage)) + gud_fb_handle_damage(gdrm, fb, &shadow_plane_state->data[0], &damage);if (!crtc->state->enable)gud_usb_set_u8(gdrm, GUD_REQ_SET_CONTROLLER_ENABLE, 0);
-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Ivo Totev
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