Re: [PATCH v2 1/3] drm/sun4i: dsi: Fix video start delay computation

[Icenowy Zheng]

ä 2019å10æ7æ GMT+08:00 äå7:51:48, Maxime Ripard <mripard@xxxxxxxxxx> åå:
>On Mon, Oct 07, 2019 at 12:03:00AM +0800, Icenowy Zheng wrote:
>> From: Jagan Teki <jagan@xxxxxxxxxxxxxxxxxxxx>
>>
>> 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@xxxxxxxxxx>
>> Signed-off-by: Jagan Teki <jagan@xxxxxxxxxxxxxxxxxxxx>
>
>you should have your SoB here.
>
>All the patches look fine, so there's no need to resend a new
>version. I'll add it if you can give it.

Sorry, I forgot it.

Signed-off-by: Icenowy Zheng <icenowy@xxxxxxx>

>
>Maxime

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