Re: [PATCH v10 0/17] Add Analogix Core Display Port Driver

[Heiko Stübner]

Hi Yakir,

Am Mittwoch, 9. Dezember 2015, 11:49:10 schrieb Yakir Yang:
> Thanks a lot for great debugging.
> 
> On 12/08/2015 11:33 PM, Heiko Stübner wrote:
> > Hi Yakir,
> > 
> > Am Montag, 7. Dezember 2015, 14:37:19 schrieb Yakir Yang:
> >>     The Samsung Exynos eDP controller and Rockchip RK3288 eDP controller
> >> 
> >> share the same IP, so a lot of parts can be re-used. I split the common
> >> code into bridge directory, then rk3288 and exynos only need to keep
> >> some platform code. Cause I can't find the exact IP name of exynos dp
> >> controller, so I decide to name dp core driver with "analogix" which I
> >> find in rk3288 eDP TRM
> > 
> > [...]
> > 
> >> Changes in v10:
> >> - Correct the ROCKCHIP_ANALOGIX_DP indentation in Kconfig to tabs here
> >> (Heiko) - Fix the wrong macro value of
> >> GRF_EDP_REF_CLK_SEL_INTER_HIWORD_MASK BIT(4) -> BIT(20)
> >> - Remove the surplus "plat_data" check. (Heiko)
> >> -       switch (dp->plat_data && dp->plat_data->dev_type) {
> >> +       switch (dp->plat_data->dev_type) {
> >> 
> >> - Revert parts of Gustavo Padovan's changes in commit:
> >> 	drm/exynos: do not start enabling DP at bind() phase
> >> 	
> >>    Add dp phy poweron function in bind time.
> > 
> > The hotplug issue is still present, but I think I found the cause. When
> > the first detect call happens, the display simply is still off. I just did
> > some very basic tracing [0] and it seems the display simply is not enabled
> > when it is supposed to get detected.
> 
> Aha, thanks, make a lot of sense.
> 
> > And it seems injecting a drm_panel_prepare early for _testing_ [1] really
> > did make the hotplug work on both my jerry and minnie.
> > 
> > So I guess we should somehow make sure the panel is actually powered when
> > detection is running. Although I'm not sure yet, how that should look
> > like.
> 
> Agree, panel should be powered up before DP controller start to detect
> hotplug signal.
> 
> > Intuition suggests, making drm_panel calls nestable (similar to
> > clk_prepare/unprepare, etc) and simply wrapping the detection code
> > in a prepare-unprepare calls, but I'm not sure if Thierry might have other
> > ideas ;-)
> 
> Due to the panel power status would influence the hotplug status, so I
> think we don't
> need to unprepared the panel unless in driver enter into suspend time.
> Things I want:
> 
> 1. Prepared the panel in driver *bind time*
> 2. Enable the panel in driver *bridge->enable time*
> 3. Disable the panel in driver *bridge->disable time*
> 4. Unprepared the panel in driver*suspend time *
> 5. Re-prepared the panel in driver *resume time*
6. Unprepare the panel in driver at *unbind time*

otherwise going that way looks nice.


> > Also my "log" below suggests some sort of mismatch between
> > prepare/unprepare calls, as there are a lot more of the prepare-side.
> 
> Yes, it's a typo too. I shouldn't place the panel->prepare in
> connector->get_modes,
> cause userspace would try to call get_modes once it receive the hotplug
> event, so
> there wouldn't have a match between panel prepare/unprepare.
> 
> Previously, I just want to ensure that panel should be power-up when
> driver try to
> read the EDID from panel, so for now must remove the prepare from
> get_modes time  :)
> 
> > And the locking issue also seems to be still there [2].
> 
> Hmm, I haven't meet this dead lock on my chromebook (ChromeOS + 4.4-rc3
> Kernel)
> 
> After look at the dead lock trace, I guess this dead lock would happened
> when hotplug
> event happened in bridge->disable time, not sure.  Would try to find
> more in trace log
> and try to reproduce this.

It is not an actual deadlock, but a warning that a deadlock might happen.
So you need to have LOCKDEP on. My kernels are currently running with

CONFIG_DEBUG_LOCK_ALLOC=y
CONFIG_PROVE_LOCKING=y
CONFIG_LOCKDEP=y
CONFIG_DEBUG_LOCKDEP=y
CONFIG_DEBUG_ATOMIC_SLEEP=y

and I see this mostly when changing between X11, console and back to X11.


Heiko

> > Heiko
> > 
> > 
> > [0]
> > [    2.797383] analogix_dp_reset
> > [    2.800709] analogix_dp_init_hpd
> > [    2.803960] analogix_dp_init_video
> > [    2.807653] rockchip-drm display-subsystem: bound ff970000.dp (ops
> > rockchip_dp_component_ops) [    2.817176] [drm] Supports vblank timestamp
> > caching Rev 2 (21.10.2013). [    2.823799] [drm] No driver support for
> > vblank timestamp query. [    2.829947] analogix_dp_detect
> > [    2.833015] analogix_dp_get_plug_in_status: hpd status 0
> > ...
> > [    2.893425] analogix_dp_get_plug_in_status: hpd status 0
> > [    2.893456] rockchip-dp ff970000.dp: failed to get hpd plug status, try
> > to force hpd [    2.893458] analogix_dp_force_hpd
> > [    2.893464] analogix_dp_get_plug_in_status: hpd status 112
> > [    2.893470] panel_simple_prepare
> > [    2.952183] rockchip-dp ff970000.dp: EDID data does not include any
> > extensions. [    2.961727] panel_simple_get_modes
> > [    3.432154] analogix_dp_detect
> > [    3.432158] analogix_dp_get_plug_in_status: hpd status 120
> > [    3.432160] panel_simple_prepare
> > [    3.433731] rockchip-dp ff970000.dp: EDID data does not include any
> > extensions. [    3.443268] panel_simple_get_modes
> > [    3.444668] panel_simple_prepare
> > [    3.444755] analogix_dp_reset
> > [    3.445078] analogix_dp_init_hpd
> > [    3.445096] panel_simple_disable
> > [    3.455349] analogix_dp_init_video
> > [    3.558323] rockchip-dp ff970000.dp: Timeout of video streamclk ok
> > [    3.558326] rockchip-dp ff970000.dp: unable to config video
> > [    3.558328] panel_simple_enable
> > [    3.573915] analogix_dp_detect
> > [    3.573919] analogix_dp_get_plug_in_status: hpd status 72
> > [    3.573921] panel_simple_prepare
> > 
> > 
> > [1]
> > diff --git a/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c
> > b/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c index 3990951..0c2dca5
> > 100644
> > --- a/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c
> > +++ b/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c
> > @@ -399,6 +399,8 @@ static int rockchip_dp_probe(struct platform_device
> > *pdev)> 
> >          dp->plat_data.panel = panel;
> > 
> > +drm_panel_prepare(dp->plat_data.panel);
> > +
> > 
> >          /*
> >          
> >           * We just use the drvdata until driver run into component
> >           * add function, and then we would set drvdata to null, so
> > 
> > [2]
> > [   11.971277] panel_simple_get_modes
> > [  OK  ] Started LSB: X display manager for KDE.
> > [  OK  ] Started LSB: Speech Dispatcher.
> > [   12.007120] panel_simple_disable
> > [   12.012323]
> > [   12.013820] ======================================================
> > [   12.019993] [ INFO: possible circular locking dependency detected ]
> > [   12.026250] 4.4.0-rc3+ #2755 Not tainted
> > [   12.030165] -------------------------------------------------------
> > [  12.036417] Xorg/793 is trying to acquire lock:
> > [   12.040855]  ((&dp->hotplug_work)){+.+...}[   12.040870]
> > [   12.040870] but task is already holding lock:
> > [   12.040871]  (crtc_ww_class_mutex){+.+.+.}, at: [<c0383600>]
> > drm_modeset_lock+0x84/0x104 [   12.040881]
> > [   12.040881] which lock already depends on the new lock.
> > [   12.040881]
> > [   12.040882]
> > [   12.040882] the existing dependency chain (in reverse order) is:
> > [   12.040883]
> > [   12.040883] -> #2 (crtc_ww_class_mutex){+.+.+.}:
> > [   12.040887]        [<c0756374>] mutex_lock_nested+0x78/0x41c
> > [   12.040893]        [<c038365c>] drm_modeset_lock+0xe0/0x104
> > [   12.040896]        [<c0377888>] drm_mode_getconnector+0x168/0x38c
> > [   12.040902]        [<c036ae58>] drm_ioctl+0x274/0x408
> > [   12.040907]        [<c017cbc8>] do_vfs_ioctl+0x670/0x750
> > [   12.040911]        [<c017cd04>] SyS_ioctl+0x5c/0x84
> > [   12.040914]        [<c000ff80>] ret_fast_syscall+0x0/0x1c
> > [   12.040920]
> > [   12.040920] -> #1 (&dev->mode_config.mutex){+.+.+.}:
> > [   12.040924]        [<c0756374>] mutex_lock_nested+0x78/0x41c
> > [   12.040928]        [<c035b3b4>] drm_helper_hpd_irq_event+0x40/0x150
> > [   12.040934]        [<c038e0b0>] analogix_dp_hotplug+0x24/0x28
> > [   12.040938]        [<c00450c4>] process_one_work+0x328/0x668
> > [   12.040942]        [<c0046334>] worker_thread+0x2cc/0x41c
> > [   12.040945]        [<c004bbe8>] kthread+0xf4/0x10c
> > [   12.040950]        [<c0010010>] ret_from_fork+0x14/0x24
> > [   12.040954]
> > [   12.040954] -> #0 ((&dp->hotplug_work)){+.+...}:
> > [   12.040958]        [<c007f4ac>] lock_acquire+0x178/0x218
> > [   12.040963]        [<c00437d0>] flush_work+0x4c/0x22c
> > [   12.040966]        [<c038e45c>] analogix_dp_bridge_disable+0x74/0xf0
> > [   12.040970]        [<c0385ef4>] drm_bridge_disable+0x34/0x38
> > [   12.040973]        [<c0359044>] drm_crtc_helper_set_mode+0x200/0x424
> > [   12.040977]        [<c0359a38>] drm_crtc_helper_set_config+0x6c0/0x988
> > [   12.040981]        [<c0373ba8>] drm_mode_set_config_internal+0x60/0xdc
> > [   12.040984]        [<c0378938>] drm_mode_setcrtc+0x3cc/0x474
> > [   12.040988]        [<c036ae58>] drm_ioctl+0x274/0x408
> > [   12.040991]        [<c017cbc8>] do_vfs_ioctl+0x670/0x750
> > [   12.040994]        [<c017cd04>] SyS_ioctl+0x5c/0x84
> > [   12.040997]        [<c000ff80>] ret_fast_syscall+0x0/0x1c
> > [   12.041001]
> > [   12.041001] other info that might help us debug this:
> > [   12.041001]
> > [   12.041002] Chain exists of:
> > [   12.041002]   (&dp->hotplug_work) --> &dev->mode_config.mutex -->
> > crtc_ww_class_mutex [   12.041007]
> > [   12.041008]  Possible unsafe locking scenario:
> > [   12.041008]
> > [   12.041009]        CPU0                    CPU1
> > [   12.041010]        ----                    ----
> > [   12.041011]   lock(crtc_ww_class_mutex);
> > [   12.041013]                               
> > lock(&dev->mode_config.mutex); [   12.041016]                            
> >    lock(crtc_ww_class_mutex); [   12.041018]   lock((&dp->hotplug_work));
> > [   12.041020]
> > [   12.041020]  *** DEADLOCK ***
> > [   12.041020]
> > [   12.041023] 3 locks held by Xorg/793:
> > [   12.041023]  #0:  (&dev->mode_config.mutex){+.+.+.}, at: [<c0383d48>]
> > drm_modeset_lock_all+0x50/0xd8 [   12.041030]  #1: 
> > (crtc_ww_class_acquire){+.+.+.}, at: [<c0383d58>]
> > drm_modeset_lock_all+0x60/0xd8 [   12.041037]  #2: 
> > (crtc_ww_class_mutex){+.+.+.}, at: [<c0383600>]
> > drm_modeset_lock+0x84/0x104 [   12.041044]
> > [   12.041044] stack backtrace:
> > [   12.041048] CPU: 3 PID: 793 Comm: Xorg Not tainted 4.4.0-rc3+ #2755
> > [   12.041049] Hardware name: Rockchip (Device Tree)
> > [   12.041059] [<c0019914>] (unwind_backtrace) from [<c0014bcc>]
> > (show_stack+0x20/0x24) [   12.041066] [<c0014bcc>] (show_stack) from
> > [<c02c4484>] (dump_stack+0x84/0xb8) [   12.041072] [<c02c4484>]
> > (dump_stack) from [<c007a2b8>] (print_circular_bug+0x278/0x2cc) [  
> > 12.041078] [<c007a2b8>] (print_circular_bug) from [<c007e850>]
> > (__lock_acquire+0x14a0/0x1aec) [   12.041082] [<c007e850>]
> > (__lock_acquire) from [<c007f4ac>] (lock_acquire+0x178/0x218) [  
> > 12.041086] [<c007f4ac>] (lock_acquire) from [<c00437d0>]
> > (flush_work+0x4c/0x22c) [   12.041091] [<c00437d0>] (flush_work) from
> > [<c038e45c>] (analogix_dp_bridge_disable+0x74/0xf0) [   12.041097]
> > [<c038e45c>] (analogix_dp_bridge_disable) from [<c0385ef4>]
> > (drm_bridge_disable+0x34/0x38) [   12.041102] [<c0385ef4>]
> > (drm_bridge_disable) from [<c0359044>]
> > (drm_crtc_helper_set_mode+0x200/0x424) [   12.041108] [<c0359044>]
> > (drm_crtc_helper_set_mode) from [<c0359a38>]
> > (drm_crtc_helper_set_config+0x6c0/0x988) [   12.041114] [<c0359a38>]
> > (drm_crtc_helper_set_config) from [<c0373ba8>]
> > (drm_mode_set_config_internal+0x60/0xdc) [   12.041119] [<c0373ba8>]
> > (drm_mode_set_config_internal) from [<c0378938>]
> > (drm_mode_setcrtc+0x3cc/0x474) [   12.041124] [<c0378938>]
> > (drm_mode_setcrtc) from [<c036ae58>] (drm_ioctl+0x274/0x408) [  
> > 12.041129] [<c036ae58>] (drm_ioctl) from [<c017cbc8>]
> > (do_vfs_ioctl+0x670/0x750) [   12.041134] [<c017cbc8>] (do_vfs_ioctl)
> > from [<c017cd04>] (SyS_ioctl+0x5c/0x84) [   12.041138] [<c017cd04>]
> > (SyS_ioctl) from [<c000ff80>] (ret_fast_syscall+0x0/0x1c) [   12.041210]
> > panel_simple_unprepare
> > [   12.041359] panel_simple_prepare
> > [   12.101638] analogix_dp_reset
> > [   12.101879] analogix_dp_init_hpd
> > [   12.101897] panel_simple_disable
> > [   12.108543] analogix_dp_irq_handler: irq-type 0
> > [   12.110452] rockchip-dp ff970000.dp: Link Training Clock Recovery
> > success [   12.111900] rockchip-dp ff970000.dp: Link Training success!
> > [   12.113384] analogix_dp_init_video
> > [   12.215825] rockchip-dp ff970000.dp: Timeout of video streamclk ok
> > [   12.215829] rockchip-dp ff970000.dp: unable to config video
> > [   12.215832] panel_simple_enable
> > ,at: [<c0043784>] flush_work+0x0/0x22c

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