Hi,
On 28/04/16 18:18, Noralf Trønnes wrote:
This adds deferred io support to drm_fb_helper. The fbdev framebuffer changes are flushed using the callback (struct drm_framebuffer *)->funcs->dirty() by a dedicated worker ensuring that it always runs in process context.
Signed-off-by: Noralf Trønnes noralf@tronnes.org Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch
Thanks for the series! Unfortunately I haven't been able to follow the discussions properly, so I hope my questions haven't been covered earlier.
Changes since v3:
- Don't use forward decl, move drm_fb_helper_dirty_work()
- Use DIV_ROUND_UP in drm_fb_helper_deferred_io()
Changes since v2:
- FB_DEFERRED_IO is now always selected by DRM_KMS_FB_HELPER, ifdef removed
- The drm_clip_rect utility functions are dropped, so open code it
- docs: use & to denote structs
Changes since v1:
- Use a dedicated worker to run the framebuffer flushing like qxl does
- Add parameter descriptions to drm_fb_helper_deferred_io
drivers/gpu/drm/Kconfig | 1 + drivers/gpu/drm/drm_fb_helper.c | 103 +++++++++++++++++++++++++++++++++++++++- include/drm/drm_fb_helper.h | 15 ++++++ 3 files changed, 118 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig index 9e4f2f1..8e6f34b 100644 --- a/drivers/gpu/drm/Kconfig +++ b/drivers/gpu/drm/Kconfig @@ -52,6 +52,7 @@ config DRM_KMS_FB_HELPER select FB_CFB_FILLRECT select FB_CFB_COPYAREA select FB_CFB_IMAGEBLIT
- select FB_DEFERRED_IO help FBDEV helpers for KMS drivers.
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index 855108e..62f849f 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -84,6 +84,15 @@ static LIST_HEAD(kernel_fb_helper_list);
- and set up an initial configuration using the detected hardware, drivers
- should call drm_fb_helper_single_add_all_connectors() followed by
- drm_fb_helper_initial_config().
- If CONFIG_FB_DEFERRED_IO is enabled and &drm_framebuffer_funcs ->dirty is
- set, the drm_fb_helper_{cfb,sys}_{write,fillrect,copyarea,imageblit}
- functions will accumulate changes and schedule &fb_helper .dirty_work to run
- right away. This worker then calls the dirty() function ensuring that it
- will always run in process context since the fb_*() function could be
- running in atomic context. If drm_fb_helper_deferred_io() is used as the
Who's calling {write,fillrect,copyarea,imageblit} in an atomic context? That sounds like a very bad idea to me...
If this is only for accumulating changes, I think it may be better to leave that to the driver as it may have better idea of how to accumulate.
But, of course, this is a helper, so if all the drivers use this kind of accumulation, it makes sense =).
Tomi