The LCD timing definitions between Linux DRM vs Allwinner are different, below diagram shows this clear differences.
Active Front Sync Back Region Porch Porch <-----------------------><----------------><--------------><--------------> //////////////////////| ////////////////////// | ////////////////////// |.................. ................ ________________ <----- [hv]display -----> <------------- [hv]sync_start ------------> <--------------------- [hv]sync_end ----------------------> <-------------------------------- [hv]total ------------------------------>
<----- lcd_[xy] --------> <- lcd_[hv]spw -> <---------- lcd_[hv]bp ---------> <-------------------------------- lcd_[hv]t ------------------------------>
The DSI driver misinterpreted the vbp term from the BSP code to refer only to the backporch, when in fact it was backporch + sync. Thus the driver incorrectly used the vertical front porch plus sync in its calculation of the DRQ set bit value, when it should not have included the sync timing.
Including additional sync timings leads to flip_done timed out as:
WARNING: CPU: 0 PID: 31 at drivers/gpu/drm/drm_atomic_helper.c:1429 drm_atomic_helper_wait_for_vblanks.part.1+0x298/0x2a0 [CRTC:46:crtc-0] vblank wait timed out Modules linked in: CPU: 0 PID: 31 Comm: kworker/0:1 Not tainted 5.1.0-next-20190514-00029-g09e5b0ed0a58 #18 Hardware name: Allwinner sun8i Family Workqueue: events deferred_probe_work_func [<c010ed54>] (unwind_backtrace) from [<c010b76c>] (show_stack+0x10/0x14) [<c010b76c>] (show_stack) from [<c0688c70>] (dump_stack+0x84/0x98) [<c0688c70>] (dump_stack) from [<c011d9e4>] (__warn+0xfc/0x114) [<c011d9e4>] (__warn) from [<c011da40>] (warn_slowpath_fmt+0x44/0x68) [<c011da40>] (warn_slowpath_fmt) from [<c040cd50>] (drm_atomic_helper_wait_for_vblanks.part.1+0x298/0x2a0) [<c040cd50>] (drm_atomic_helper_wait_for_vblanks.part.1) from [<c040e694>] (drm_atomic_helper_commit_tail_rpm+0x5c/0x6c) [<c040e694>] (drm_atomic_helper_commit_tail_rpm) from [<c040e4dc>] (commit_tail+0x40/0x6c) [<c040e4dc>] (commit_tail) from [<c040e5cc>] (drm_atomic_helper_commit+0xbc/0x128) [<c040e5cc>] (drm_atomic_helper_commit) from [<c0411b64>] (restore_fbdev_mode_atomic+0x1cc/0x1dc) [<c0411b64>] (restore_fbdev_mode_atomic) from [<c04156f8>] (drm_fb_helper_restore_fbdev_mode_unlocked+0x54/0xa0) [<c04156f8>] (drm_fb_helper_restore_fbdev_mode_unlocked) from [<c0415774>] (drm_fb_helper_set_par+0x30/0x54) [<c0415774>] (drm_fb_helper_set_par) from [<c03ad450>] (fbcon_init+0x560/0x5ac) [<c03ad450>] (fbcon_init) from [<c03eb8a0>] (visual_init+0xbc/0x104) [<c03eb8a0>] (visual_init) from [<c03ed1b8>] (do_bind_con_driver+0x1b0/0x390) [<c03ed1b8>] (do_bind_con_driver) from [<c03ed780>] (do_take_over_console+0x13c/0x1c4) [<c03ed780>] (do_take_over_console) from [<c03ad800>] (do_fbcon_takeover+0x74/0xcc) [<c03ad800>] (do_fbcon_takeover) from [<c013c9c8>] (notifier_call_chain+0x44/0x84) [<c013c9c8>] (notifier_call_chain) from [<c013cd20>] (__blocking_notifier_call_chain+0x48/0x60) [<c013cd20>] (__blocking_notifier_call_chain) from [<c013cd50>] (blocking_notifier_call_chain+0x18/0x20) [<c013cd50>] (blocking_notifier_call_chain) from [<c03a6e44>] (register_framebuffer+0x1e0/0x2f8) [<c03a6e44>] (register_framebuffer) from [<c04153c0>] (__drm_fb_helper_initial_config_and_unlock+0x2fc/0x50c) [<c04153c0>] (__drm_fb_helper_initial_config_and_unlock) from [<c04158c8>] (drm_fbdev_client_hotplug+0xe8/0x1b8) [<c04158c8>] (drm_fbdev_client_hotplug) from [<c0415a20>] (drm_fbdev_generic_setup+0x88/0x118) [<c0415a20>] (drm_fbdev_generic_setup) from [<c043f060>] (sun4i_drv_bind+0x128/0x160) [<c043f060>] (sun4i_drv_bind) from [<c044b598>] (try_to_bring_up_master+0x164/0x1a0) [<c044b598>] (try_to_bring_up_master) from [<c044b668>] (__component_add+0x94/0x140) [<c044b668>] (__component_add) from [<c0445e1c>] (sun6i_dsi_probe+0x144/0x234) [<c0445e1c>] (sun6i_dsi_probe) from [<c0452ef4>] (platform_drv_probe+0x48/0x9c) [<c0452ef4>] (platform_drv_probe) from [<c04512cc>] (really_probe+0x1dc/0x2c8) [<c04512cc>] (really_probe) from [<c0451518>] (driver_probe_device+0x60/0x160) [<c0451518>] (driver_probe_device) from [<c044f7a4>] (bus_for_each_drv+0x74/0xb8) [<c044f7a4>] (bus_for_each_drv) from [<c045107c>] (__device_attach+0xd0/0x13c) [<c045107c>] (__device_attach) from [<c0450474>] (bus_probe_device+0x84/0x8c) [<c0450474>] (bus_probe_device) from [<c0450900>] (deferred_probe_work_func+0x64/0x90) [<c0450900>] (deferred_probe_work_func) from [<c0135970>] (process_one_work+0x204/0x420) [<c0135970>] (process_one_work) from [<c013690c>] (worker_thread+0x274/0x5a0) [<c013690c>] (worker_thread) from [<c013b3d8>] (kthread+0x11c/0x14c) [<c013b3d8>] (kthread) from [<c01010e8>] (ret_from_fork+0x14/0x2c) Exception stack(0xde539fb0 to 0xde539ff8) 9fa0: 00000000 00000000 00000000 00000000 9fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 9fe0: 00000000 00000000 00000000 00000000 00000013 00000000 ---[ end trace 495200a78b24980e ]--- random: fast init done [drm:drm_atomic_helper_wait_for_dependencies] *ERROR* [CRTC:46:crtc-0] flip_done timed out [drm:drm_atomic_helper_wait_for_dependencies] *ERROR* [CONNECTOR:48:DSI-1] flip_done timed out [drm:drm_atomic_helper_wait_for_dependencies] *ERROR* [PLANE:30:plane-0] flip_done timed out
With the terms(as described in above diagram) fixed, the panel displays correctly without any timeouts.
Tested-by: Merlijn Wajer merlijn@wizzup.org Signed-off-by: Jagan Teki jagan@amarulasolutions.com --- drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c index c9c99c52bf1e..446dc56cc44b 100644 --- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c +++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c @@ -376,7 +376,7 @@ static u16 sun6i_dsi_get_video_start_delay(struct sun6i_dsi *dsi, * working in DSI panels available in mainline. */ u8 start = 1; - u16 delay = mode->vtotal - (mode->vsync_end - mode->vdisplay) + start; + u16 delay = mode->vtotal - (mode->vsync_start - mode->vdisplay) + start;
if (delay > mode->vtotal) delay = delay % mode->vtotal;