mirror of https://gitee.com/openkylin/linux.git
fc8fd40eb2
So I just wanted to add a new field to struct drm_device and accidentally stumbled over something. According to comments dev->open_count is protected by dev->count_lock, but that's totally not the case. It's protected by drm_global_mutex. Unfortunately the vga switcheroo callbacks took this comment at face value. The problem is that we can't just take the drm_global_mutex because: - It would lead to a locking inversion with the driver load/unload paths. - It wouldn't actually protect anything, for that we'd need to wrap the entire vga switcheroo code in the drm_global_mutex. And I'm not sure whether that would actually solve anything. What we probably want is a try_to_grab_switcheroo reference kind of thing which is used in the driver's ->open callback. Then we could move all that ->can_switch madness into the vga switcheroo core where it really belongs. But since that would amount to real work take the easy way out and just add a comment. It's definitely not going to make anything worse since doing switcheroo state changes while restarting X just isn't recommended. Even though the delayed switching code does exactly that. v2: - Simplify the ->can_switch implementations more (Thierry) - Fix comment about the dev->open_count locking (Thierry) Cc: Thierry Reding <treding@nvidia.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> (v1) Reviewed-by: Thierry Reding <treding@nvidia.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> |
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| .. | ||
| bridge | ||
| i2c | ||
| ttm | ||
| drmP.h | ||
| drm_agpsupport.h | ||
| drm_buffer.h | ||
| drm_cache.h | ||
| drm_core.h | ||
| drm_crtc.h | ||
| drm_crtc_helper.h | ||
| drm_dp_helper.h | ||
| drm_edid.h | ||
| drm_encoder_slave.h | ||
| drm_fb_cma_helper.h | ||
| drm_fb_helper.h | ||
| drm_fixed.h | ||
| drm_flip_work.h | ||
| drm_gem_cma_helper.h | ||
| drm_global.h | ||
| drm_hashtab.h | ||
| drm_mem_util.h | ||
| drm_memory.h | ||
| drm_mipi_dsi.h | ||
| drm_mm.h | ||
| drm_modes.h | ||
| drm_os_linux.h | ||
| drm_panel.h | ||
| drm_pciids.h | ||
| drm_plane_helper.h | ||
| drm_rect.h | ||
| drm_sysfs.h | ||
| drm_usb.h | ||
| drm_vma_manager.h | ||
| exynos_drm.h | ||
| gma_drm.h | ||
| i915_drm.h | ||
| i915_pciids.h | ||
| i915_powerwell.h | ||
| intel-gtt.h | ||