* [PATCH v2] drm/msm/dp: remove fail safe mode related code
@ 2022-04-26 5:56 ` Kuogee Hsieh
0 siblings, 0 replies; 8+ messages in thread
From: Kuogee Hsieh @ 2022-04-26 5:56 UTC (permalink / raw)
To: robdclark, sean, swboyd, vkoul, daniel, airlied, agross,
dmitry.baryshkov, bjorn.andersson
Cc: quic_abhinavk, quic_aravindh, quic_khsieh, quic_sbillaka,
freedreno, dri-devel, linux-arm-msm, linux-kernel
Current DP driver implementation has adding safe mode done at
dp_hpd_plug_handle() which is expected to be executed under event
thread context.
However there is possible circular locking happen (see blow stack trace)
after edp driver call dp_hpd_plug_handle() from dp_bridge_enable() which
is executed under drm_thread context.
After review all possibilities methods and as discussed on
https://patchwork.freedesktop.org/patch/483155/, supporting EDID
compliance tests in the driver is quite hacky. As seen with other
vendor drivers, supporting these will be much easier with IGT. Hence
removing all the related fail safe code for it so that no possibility
of circular lock will happen.
======================================================
WARNING: possible circular locking dependency detected
5.15.35-lockdep #6 Tainted: G W
------------------------------------------------------
frecon/429 is trying to acquire lock:
ffffff808dc3c4e8 (&dev->mode_config.mutex){+.+.}-{3:3}, at:
dp_panel_add_fail_safe_mode+0x4c/0xa0
but task is already holding lock:
ffffff808dc441e0 (&kms->commit_lock[i]){+.+.}-{3:3}, at: lock_crtcs+0xb4/0x124
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #3 (&kms->commit_lock[i]){+.+.}-{3:3}:
__mutex_lock_common+0x174/0x1a64
mutex_lock_nested+0x98/0xac
lock_crtcs+0xb4/0x124
msm_atomic_commit_tail+0x330/0x748
commit_tail+0x19c/0x278
drm_atomic_helper_commit+0x1dc/0x1f0
drm_atomic_commit+0xc0/0xd8
drm_atomic_helper_set_config+0xb4/0x134
drm_mode_setcrtc+0x688/0x1248
drm_ioctl_kernel+0x1e4/0x338
drm_ioctl+0x3a4/0x684
__arm64_sys_ioctl+0x118/0x154
invoke_syscall+0x78/0x224
el0_svc_common+0x178/0x200
do_el0_svc+0x94/0x13c
el0_svc+0x5c/0xec
el0t_64_sync_handler+0x78/0x108
el0t_64_sync+0x1a4/0x1a8
-> #2 (crtc_ww_class_mutex){+.+.}-{3:3}:
__mutex_lock_common+0x174/0x1a64
ww_mutex_lock+0xb8/0x278
modeset_lock+0x304/0x4ac
drm_modeset_lock+0x4c/0x7c
drmm_mode_config_init+0x4a8/0xc50
msm_drm_init+0x274/0xac0
msm_drm_bind+0x20/0x2c
try_to_bring_up_master+0x3dc/0x470
__component_add+0x18c/0x3c0
component_add+0x1c/0x28
dp_display_probe+0x954/0xa98
platform_probe+0x124/0x15c
really_probe+0x1b0/0x5f8
__driver_probe_device+0x174/0x20c
driver_probe_device+0x70/0x134
__device_attach_driver+0x130/0x1d0
bus_for_each_drv+0xfc/0x14c
__device_attach+0x1bc/0x2bc
device_initial_probe+0x1c/0x28
bus_probe_device+0x94/0x178
deferred_probe_work_func+0x1a4/0x1f0
process_one_work+0x5d4/0x9dc
worker_thread+0x898/0xccc
kthread+0x2d4/0x3d4
ret_from_fork+0x10/0x20
-> #1 (crtc_ww_class_acquire){+.+.}-{0:0}:
ww_acquire_init+0x1c4/0x2c8
drm_modeset_acquire_init+0x44/0xc8
drm_helper_probe_single_connector_modes+0xb0/0x12dc
drm_mode_getconnector+0x5dc/0xfe8
drm_ioctl_kernel+0x1e4/0x338
drm_ioctl+0x3a4/0x684
__arm64_sys_ioctl+0x118/0x154
invoke_syscall+0x78/0x224
el0_svc_common+0x178/0x200
do_el0_svc+0x94/0x13c
el0_svc+0x5c/0xec
el0t_64_sync_handler+0x78/0x108
el0t_64_sync+0x1a4/0x1a8
-> #0 (&dev->mode_config.mutex){+.+.}-{3:3}:
__lock_acquire+0x2650/0x672c
lock_acquire+0x1b4/0x4ac
__mutex_lock_common+0x174/0x1a64
mutex_lock_nested+0x98/0xac
dp_panel_add_fail_safe_mode+0x4c/0xa0
dp_hpd_plug_handle+0x1f0/0x280
dp_bridge_enable+0x94/0x2b8
drm_atomic_bridge_chain_enable+0x11c/0x168
drm_atomic_helper_commit_modeset_enables+0x500/0x740
msm_atomic_commit_tail+0x3e4/0x748
commit_tail+0x19c/0x278
drm_atomic_helper_commit+0x1dc/0x1f0
drm_atomic_commit+0xc0/0xd8
drm_atomic_helper_set_config+0xb4/0x134
drm_mode_setcrtc+0x688/0x1248
drm_ioctl_kernel+0x1e4/0x338
drm_ioctl+0x3a4/0x684
__arm64_sys_ioctl+0x118/0x154
invoke_syscall+0x78/0x224
el0_svc_common+0x178/0x200
do_el0_svc+0x94/0x13c
el0_svc+0x5c/0xec
el0t_64_sync_handler+0x78/0x108
el0t_64_sync+0x1a4/0x1a8
Changes in v2:
-- re text commit title
-- remove all fail safe mode
Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
---
drivers/gpu/drm/msm/dp/dp_display.c | 6 ------
drivers/gpu/drm/msm/dp/dp_panel.c | 11 -----------
2 files changed, 17 deletions(-)
diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
index 92cd50f..01453db 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -555,12 +555,6 @@ static int dp_hpd_plug_handle(struct dp_display_private *dp, u32 data)
mutex_unlock(&dp->event_mutex);
- /*
- * add fail safe mode outside event_mutex scope
- * to avoid potiential circular lock with drm thread
- */
- dp_panel_add_fail_safe_mode(dp->dp_display.connector);
-
/* uevent will complete connection part */
return 0;
};
diff --git a/drivers/gpu/drm/msm/dp/dp_panel.c b/drivers/gpu/drm/msm/dp/dp_panel.c
index 1aa9aa8c..8ff174a 100644
--- a/drivers/gpu/drm/msm/dp/dp_panel.c
+++ b/drivers/gpu/drm/msm/dp/dp_panel.c
@@ -151,15 +151,6 @@ static int dp_panel_update_modes(struct drm_connector *connector,
return rc;
}
-void dp_panel_add_fail_safe_mode(struct drm_connector *connector)
-{
- /* fail safe edid */
- mutex_lock(&connector->dev->mode_config.mutex);
- if (drm_add_modes_noedid(connector, 640, 480))
- drm_set_preferred_mode(connector, 640, 480);
- mutex_unlock(&connector->dev->mode_config.mutex);
-}
-
int dp_panel_read_sink_caps(struct dp_panel *dp_panel,
struct drm_connector *connector)
{
@@ -215,8 +206,6 @@ int dp_panel_read_sink_caps(struct dp_panel *dp_panel,
rc = -ETIMEDOUT;
goto end;
}
-
- dp_panel_add_fail_safe_mode(connector);
}
if (panel->aux_cfg_update_done) {
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
^ permalink raw reply related [flat|nested] 8+ messages in thread
* [PATCH v2] drm/msm/dp: remove fail safe mode related code
@ 2022-04-26 5:56 ` Kuogee Hsieh
0 siblings, 0 replies; 8+ messages in thread
From: Kuogee Hsieh @ 2022-04-26 5:56 UTC (permalink / raw)
To: robdclark, sean, swboyd, vkoul, daniel, airlied, agross,
dmitry.baryshkov, bjorn.andersson
Cc: quic_sbillaka, linux-arm-msm, quic_abhinavk, dri-devel,
quic_khsieh, quic_aravindh, freedreno, linux-kernel
Current DP driver implementation has adding safe mode done at
dp_hpd_plug_handle() which is expected to be executed under event
thread context.
However there is possible circular locking happen (see blow stack trace)
after edp driver call dp_hpd_plug_handle() from dp_bridge_enable() which
is executed under drm_thread context.
After review all possibilities methods and as discussed on
https://patchwork.freedesktop.org/patch/483155/, supporting EDID
compliance tests in the driver is quite hacky. As seen with other
vendor drivers, supporting these will be much easier with IGT. Hence
removing all the related fail safe code for it so that no possibility
of circular lock will happen.
======================================================
WARNING: possible circular locking dependency detected
5.15.35-lockdep #6 Tainted: G W
------------------------------------------------------
frecon/429 is trying to acquire lock:
ffffff808dc3c4e8 (&dev->mode_config.mutex){+.+.}-{3:3}, at:
dp_panel_add_fail_safe_mode+0x4c/0xa0
but task is already holding lock:
ffffff808dc441e0 (&kms->commit_lock[i]){+.+.}-{3:3}, at: lock_crtcs+0xb4/0x124
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #3 (&kms->commit_lock[i]){+.+.}-{3:3}:
__mutex_lock_common+0x174/0x1a64
mutex_lock_nested+0x98/0xac
lock_crtcs+0xb4/0x124
msm_atomic_commit_tail+0x330/0x748
commit_tail+0x19c/0x278
drm_atomic_helper_commit+0x1dc/0x1f0
drm_atomic_commit+0xc0/0xd8
drm_atomic_helper_set_config+0xb4/0x134
drm_mode_setcrtc+0x688/0x1248
drm_ioctl_kernel+0x1e4/0x338
drm_ioctl+0x3a4/0x684
__arm64_sys_ioctl+0x118/0x154
invoke_syscall+0x78/0x224
el0_svc_common+0x178/0x200
do_el0_svc+0x94/0x13c
el0_svc+0x5c/0xec
el0t_64_sync_handler+0x78/0x108
el0t_64_sync+0x1a4/0x1a8
-> #2 (crtc_ww_class_mutex){+.+.}-{3:3}:
__mutex_lock_common+0x174/0x1a64
ww_mutex_lock+0xb8/0x278
modeset_lock+0x304/0x4ac
drm_modeset_lock+0x4c/0x7c
drmm_mode_config_init+0x4a8/0xc50
msm_drm_init+0x274/0xac0
msm_drm_bind+0x20/0x2c
try_to_bring_up_master+0x3dc/0x470
__component_add+0x18c/0x3c0
component_add+0x1c/0x28
dp_display_probe+0x954/0xa98
platform_probe+0x124/0x15c
really_probe+0x1b0/0x5f8
__driver_probe_device+0x174/0x20c
driver_probe_device+0x70/0x134
__device_attach_driver+0x130/0x1d0
bus_for_each_drv+0xfc/0x14c
__device_attach+0x1bc/0x2bc
device_initial_probe+0x1c/0x28
bus_probe_device+0x94/0x178
deferred_probe_work_func+0x1a4/0x1f0
process_one_work+0x5d4/0x9dc
worker_thread+0x898/0xccc
kthread+0x2d4/0x3d4
ret_from_fork+0x10/0x20
-> #1 (crtc_ww_class_acquire){+.+.}-{0:0}:
ww_acquire_init+0x1c4/0x2c8
drm_modeset_acquire_init+0x44/0xc8
drm_helper_probe_single_connector_modes+0xb0/0x12dc
drm_mode_getconnector+0x5dc/0xfe8
drm_ioctl_kernel+0x1e4/0x338
drm_ioctl+0x3a4/0x684
__arm64_sys_ioctl+0x118/0x154
invoke_syscall+0x78/0x224
el0_svc_common+0x178/0x200
do_el0_svc+0x94/0x13c
el0_svc+0x5c/0xec
el0t_64_sync_handler+0x78/0x108
el0t_64_sync+0x1a4/0x1a8
-> #0 (&dev->mode_config.mutex){+.+.}-{3:3}:
__lock_acquire+0x2650/0x672c
lock_acquire+0x1b4/0x4ac
__mutex_lock_common+0x174/0x1a64
mutex_lock_nested+0x98/0xac
dp_panel_add_fail_safe_mode+0x4c/0xa0
dp_hpd_plug_handle+0x1f0/0x280
dp_bridge_enable+0x94/0x2b8
drm_atomic_bridge_chain_enable+0x11c/0x168
drm_atomic_helper_commit_modeset_enables+0x500/0x740
msm_atomic_commit_tail+0x3e4/0x748
commit_tail+0x19c/0x278
drm_atomic_helper_commit+0x1dc/0x1f0
drm_atomic_commit+0xc0/0xd8
drm_atomic_helper_set_config+0xb4/0x134
drm_mode_setcrtc+0x688/0x1248
drm_ioctl_kernel+0x1e4/0x338
drm_ioctl+0x3a4/0x684
__arm64_sys_ioctl+0x118/0x154
invoke_syscall+0x78/0x224
el0_svc_common+0x178/0x200
do_el0_svc+0x94/0x13c
el0_svc+0x5c/0xec
el0t_64_sync_handler+0x78/0x108
el0t_64_sync+0x1a4/0x1a8
Changes in v2:
-- re text commit title
-- remove all fail safe mode
Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
---
drivers/gpu/drm/msm/dp/dp_display.c | 6 ------
drivers/gpu/drm/msm/dp/dp_panel.c | 11 -----------
2 files changed, 17 deletions(-)
diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
index 92cd50f..01453db 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -555,12 +555,6 @@ static int dp_hpd_plug_handle(struct dp_display_private *dp, u32 data)
mutex_unlock(&dp->event_mutex);
- /*
- * add fail safe mode outside event_mutex scope
- * to avoid potiential circular lock with drm thread
- */
- dp_panel_add_fail_safe_mode(dp->dp_display.connector);
-
/* uevent will complete connection part */
return 0;
};
diff --git a/drivers/gpu/drm/msm/dp/dp_panel.c b/drivers/gpu/drm/msm/dp/dp_panel.c
index 1aa9aa8c..8ff174a 100644
--- a/drivers/gpu/drm/msm/dp/dp_panel.c
+++ b/drivers/gpu/drm/msm/dp/dp_panel.c
@@ -151,15 +151,6 @@ static int dp_panel_update_modes(struct drm_connector *connector,
return rc;
}
-void dp_panel_add_fail_safe_mode(struct drm_connector *connector)
-{
- /* fail safe edid */
- mutex_lock(&connector->dev->mode_config.mutex);
- if (drm_add_modes_noedid(connector, 640, 480))
- drm_set_preferred_mode(connector, 640, 480);
- mutex_unlock(&connector->dev->mode_config.mutex);
-}
-
int dp_panel_read_sink_caps(struct dp_panel *dp_panel,
struct drm_connector *connector)
{
@@ -215,8 +206,6 @@ int dp_panel_read_sink_caps(struct dp_panel *dp_panel,
rc = -ETIMEDOUT;
goto end;
}
-
- dp_panel_add_fail_safe_mode(connector);
}
if (panel->aux_cfg_update_done) {
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH v2] drm/msm/dp: remove fail safe mode related code
2022-04-26 5:56 ` Kuogee Hsieh
@ 2022-04-26 6:00 ` Stephen Boyd
-1 siblings, 0 replies; 8+ messages in thread
From: Stephen Boyd @ 2022-04-26 6:00 UTC (permalink / raw)
To: Kuogee Hsieh, agross, airlied, bjorn.andersson, daniel,
dmitry.baryshkov, robdclark, sean, vkoul
Cc: quic_abhinavk, quic_aravindh, quic_sbillaka, freedreno,
dri-devel, linux-arm-msm, linux-kernel
Quoting Kuogee Hsieh (2022-04-25 22:56:35)
> Current DP driver implementation has adding safe mode done at
> dp_hpd_plug_handle() which is expected to be executed under event
> thread context.
>
> However there is possible circular locking happen (see blow stack trace)
> after edp driver call dp_hpd_plug_handle() from dp_bridge_enable() which
> is executed under drm_thread context.
>
> After review all possibilities methods and as discussed on
> https://patchwork.freedesktop.org/patch/483155/, supporting EDID
> compliance tests in the driver is quite hacky. As seen with other
> vendor drivers, supporting these will be much easier with IGT. Hence
> removing all the related fail safe code for it so that no possibility
> of circular lock will happen.
[...]
>
> Changes in v2:
> -- re text commit title
> -- remove all fail safe mode
>
> Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
Should add some Fixes tags here, probably for the first introduction of
this logic and the one that moved stuff around to try to avoid the
lockdep warning.
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2] drm/msm/dp: remove fail safe mode related code
@ 2022-04-26 6:00 ` Stephen Boyd
0 siblings, 0 replies; 8+ messages in thread
From: Stephen Boyd @ 2022-04-26 6:00 UTC (permalink / raw)
To: Kuogee Hsieh, agross, airlied, bjorn.andersson, daniel,
dmitry.baryshkov, robdclark, sean, vkoul
Cc: quic_sbillaka, linux-arm-msm, quic_abhinavk, dri-devel,
linux-kernel, quic_aravindh, freedreno
Quoting Kuogee Hsieh (2022-04-25 22:56:35)
> Current DP driver implementation has adding safe mode done at
> dp_hpd_plug_handle() which is expected to be executed under event
> thread context.
>
> However there is possible circular locking happen (see blow stack trace)
> after edp driver call dp_hpd_plug_handle() from dp_bridge_enable() which
> is executed under drm_thread context.
>
> After review all possibilities methods and as discussed on
> https://patchwork.freedesktop.org/patch/483155/, supporting EDID
> compliance tests in the driver is quite hacky. As seen with other
> vendor drivers, supporting these will be much easier with IGT. Hence
> removing all the related fail safe code for it so that no possibility
> of circular lock will happen.
[...]
>
> Changes in v2:
> -- re text commit title
> -- remove all fail safe mode
>
> Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
Should add some Fixes tags here, probably for the first introduction of
this logic and the one that moved stuff around to try to avoid the
lockdep warning.
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2] drm/msm/dp: remove fail safe mode related code
2022-04-26 6:00 ` Stephen Boyd
@ 2022-04-26 17:36 ` Abhinav Kumar
-1 siblings, 0 replies; 8+ messages in thread
From: Abhinav Kumar @ 2022-04-26 17:36 UTC (permalink / raw)
To: Stephen Boyd, Kuogee Hsieh, agross, airlied, bjorn.andersson,
daniel, dmitry.baryshkov, robdclark, sean, vkoul
Cc: quic_aravindh, quic_sbillaka, freedreno, dri-devel,
linux-arm-msm, linux-kernel
On 4/25/2022 11:00 PM, Stephen Boyd wrote:
> Quoting Kuogee Hsieh (2022-04-25 22:56:35)
>> Current DP driver implementation has adding safe mode done at
>> dp_hpd_plug_handle() which is expected to be executed under event
>> thread context.
>>
>> However there is possible circular locking happen (see blow stack trace)
>> after edp driver call dp_hpd_plug_handle() from dp_bridge_enable() which
>> is executed under drm_thread context.
>>
>> After review all possibilities methods and as discussed on
>> https://patchwork.freedesktop.org/patch/483155/, supporting EDID
>> compliance tests in the driver is quite hacky. As seen with other
>> vendor drivers, supporting these will be much easier with IGT. Hence
>> removing all the related fail safe code for it so that no possibility
>> of circular lock will happen.
> [...]
>>
>> Changes in v2:
>> -- re text commit title
>> -- remove all fail safe mode
>>
>> Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
>
> Should add some Fixes tags here, probably for the first introduction of
> this logic and the one that moved stuff around to try to avoid the
> lockdep warning.
Fixes: 8b2c181 ("drm/msm/dp: add fail safe mode outside of event_mutex
context")
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2] drm/msm/dp: remove fail safe mode related code
@ 2022-04-26 17:36 ` Abhinav Kumar
0 siblings, 0 replies; 8+ messages in thread
From: Abhinav Kumar @ 2022-04-26 17:36 UTC (permalink / raw)
To: Stephen Boyd, Kuogee Hsieh, agross, airlied, bjorn.andersson,
daniel, dmitry.baryshkov, robdclark, sean, vkoul
Cc: quic_sbillaka, linux-arm-msm, linux-kernel, dri-devel,
quic_aravindh, freedreno
On 4/25/2022 11:00 PM, Stephen Boyd wrote:
> Quoting Kuogee Hsieh (2022-04-25 22:56:35)
>> Current DP driver implementation has adding safe mode done at
>> dp_hpd_plug_handle() which is expected to be executed under event
>> thread context.
>>
>> However there is possible circular locking happen (see blow stack trace)
>> after edp driver call dp_hpd_plug_handle() from dp_bridge_enable() which
>> is executed under drm_thread context.
>>
>> After review all possibilities methods and as discussed on
>> https://patchwork.freedesktop.org/patch/483155/, supporting EDID
>> compliance tests in the driver is quite hacky. As seen with other
>> vendor drivers, supporting these will be much easier with IGT. Hence
>> removing all the related fail safe code for it so that no possibility
>> of circular lock will happen.
> [...]
>>
>> Changes in v2:
>> -- re text commit title
>> -- remove all fail safe mode
>>
>> Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
>
> Should add some Fixes tags here, probably for the first introduction of
> this logic and the one that moved stuff around to try to avoid the
> lockdep warning.
Fixes: 8b2c181 ("drm/msm/dp: add fail safe mode outside of event_mutex
context")
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2] drm/msm/dp: remove fail safe mode related code
2022-04-26 5:56 ` Kuogee Hsieh
@ 2022-04-26 18:48 ` Doug Anderson
-1 siblings, 0 replies; 8+ messages in thread
From: Doug Anderson @ 2022-04-26 18:48 UTC (permalink / raw)
To: Kuogee Hsieh
Cc: Rob Clark, Sean Paul, Stephen Boyd, Vinod Koul, Daniel Vetter,
David Airlie, Andy Gross, Dmitry Baryshkov, Bjorn Andersson,
Abhinav Kumar (QUIC), Aravind Venkateswaran (QUIC),
Sankeerth Billakanti, freedreno, dri-devel, linux-arm-msm, LKML
Hi,
On Mon, Apr 25, 2022 at 10:56 PM Kuogee Hsieh <quic_khsieh@quicinc.com> wrote:
>
> Current DP driver implementation has adding safe mode done at
> dp_hpd_plug_handle() which is expected to be executed under event
> thread context.
>
> However there is possible circular locking happen (see blow stack trace)
> after edp driver call dp_hpd_plug_handle() from dp_bridge_enable() which
> is executed under drm_thread context.
>
> After review all possibilities methods and as discussed on
> https://patchwork.freedesktop.org/patch/483155/, supporting EDID
> compliance tests in the driver is quite hacky. As seen with other
> vendor drivers, supporting these will be much easier with IGT. Hence
> removing all the related fail safe code for it so that no possibility
> of circular lock will happen.
>
> ======================================================
> WARNING: possible circular locking dependency detected
> 5.15.35-lockdep #6 Tainted: G W
> ------------------------------------------------------
> frecon/429 is trying to acquire lock:
> ffffff808dc3c4e8 (&dev->mode_config.mutex){+.+.}-{3:3}, at:
> dp_panel_add_fail_safe_mode+0x4c/0xa0
>
> but task is already holding lock:
> ffffff808dc441e0 (&kms->commit_lock[i]){+.+.}-{3:3}, at: lock_crtcs+0xb4/0x124
>
> which lock already depends on the new lock.
>
> the existing dependency chain (in reverse order) is:
>
> -> #3 (&kms->commit_lock[i]){+.+.}-{3:3}:
> __mutex_lock_common+0x174/0x1a64
> mutex_lock_nested+0x98/0xac
> lock_crtcs+0xb4/0x124
> msm_atomic_commit_tail+0x330/0x748
> commit_tail+0x19c/0x278
> drm_atomic_helper_commit+0x1dc/0x1f0
> drm_atomic_commit+0xc0/0xd8
> drm_atomic_helper_set_config+0xb4/0x134
> drm_mode_setcrtc+0x688/0x1248
> drm_ioctl_kernel+0x1e4/0x338
> drm_ioctl+0x3a4/0x684
> __arm64_sys_ioctl+0x118/0x154
> invoke_syscall+0x78/0x224
> el0_svc_common+0x178/0x200
> do_el0_svc+0x94/0x13c
> el0_svc+0x5c/0xec
> el0t_64_sync_handler+0x78/0x108
> el0t_64_sync+0x1a4/0x1a8
>
> -> #2 (crtc_ww_class_mutex){+.+.}-{3:3}:
> __mutex_lock_common+0x174/0x1a64
> ww_mutex_lock+0xb8/0x278
> modeset_lock+0x304/0x4ac
> drm_modeset_lock+0x4c/0x7c
> drmm_mode_config_init+0x4a8/0xc50
> msm_drm_init+0x274/0xac0
> msm_drm_bind+0x20/0x2c
> try_to_bring_up_master+0x3dc/0x470
> __component_add+0x18c/0x3c0
> component_add+0x1c/0x28
> dp_display_probe+0x954/0xa98
> platform_probe+0x124/0x15c
> really_probe+0x1b0/0x5f8
> __driver_probe_device+0x174/0x20c
> driver_probe_device+0x70/0x134
> __device_attach_driver+0x130/0x1d0
> bus_for_each_drv+0xfc/0x14c
> __device_attach+0x1bc/0x2bc
> device_initial_probe+0x1c/0x28
> bus_probe_device+0x94/0x178
> deferred_probe_work_func+0x1a4/0x1f0
> process_one_work+0x5d4/0x9dc
> worker_thread+0x898/0xccc
> kthread+0x2d4/0x3d4
> ret_from_fork+0x10/0x20
>
> -> #1 (crtc_ww_class_acquire){+.+.}-{0:0}:
> ww_acquire_init+0x1c4/0x2c8
> drm_modeset_acquire_init+0x44/0xc8
> drm_helper_probe_single_connector_modes+0xb0/0x12dc
> drm_mode_getconnector+0x5dc/0xfe8
> drm_ioctl_kernel+0x1e4/0x338
> drm_ioctl+0x3a4/0x684
> __arm64_sys_ioctl+0x118/0x154
> invoke_syscall+0x78/0x224
> el0_svc_common+0x178/0x200
> do_el0_svc+0x94/0x13c
> el0_svc+0x5c/0xec
> el0t_64_sync_handler+0x78/0x108
> el0t_64_sync+0x1a4/0x1a8
>
> -> #0 (&dev->mode_config.mutex){+.+.}-{3:3}:
> __lock_acquire+0x2650/0x672c
> lock_acquire+0x1b4/0x4ac
> __mutex_lock_common+0x174/0x1a64
> mutex_lock_nested+0x98/0xac
> dp_panel_add_fail_safe_mode+0x4c/0xa0
> dp_hpd_plug_handle+0x1f0/0x280
> dp_bridge_enable+0x94/0x2b8
> drm_atomic_bridge_chain_enable+0x11c/0x168
> drm_atomic_helper_commit_modeset_enables+0x500/0x740
> msm_atomic_commit_tail+0x3e4/0x748
> commit_tail+0x19c/0x278
> drm_atomic_helper_commit+0x1dc/0x1f0
> drm_atomic_commit+0xc0/0xd8
> drm_atomic_helper_set_config+0xb4/0x134
> drm_mode_setcrtc+0x688/0x1248
> drm_ioctl_kernel+0x1e4/0x338
> drm_ioctl+0x3a4/0x684
> __arm64_sys_ioctl+0x118/0x154
> invoke_syscall+0x78/0x224
> el0_svc_common+0x178/0x200
> do_el0_svc+0x94/0x13c
> el0_svc+0x5c/0xec
> el0t_64_sync_handler+0x78/0x108
> el0t_64_sync+0x1a4/0x1a8
>
> Changes in v2:
> -- re text commit title
> -- remove all fail safe mode
>
> Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
Reported-by: Douglas Anderson <dianders@chromium.org>
Fixes: f1b47e6a8df8 ("drm/msm/dp: remove fail safe mode related code")
> @@ -151,15 +151,6 @@ static int dp_panel_update_modes(struct drm_connector *connector,
> return rc;
> }
>
> -void dp_panel_add_fail_safe_mode(struct drm_connector *connector)
> -{
> - /* fail safe edid */
> - mutex_lock(&connector->dev->mode_config.mutex);
> - if (drm_add_modes_noedid(connector, 640, 480))
> - drm_set_preferred_mode(connector, 640, 480);
> - mutex_unlock(&connector->dev->mode_config.mutex);
> -}
You removed this function but you forgot to remove it from the header
in "drivers/gpu/drm/msm/dp/dp_panel.h"
-Doug
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2] drm/msm/dp: remove fail safe mode related code
@ 2022-04-26 18:48 ` Doug Anderson
0 siblings, 0 replies; 8+ messages in thread
From: Doug Anderson @ 2022-04-26 18:48 UTC (permalink / raw)
To: Kuogee Hsieh
Cc: Sankeerth Billakanti, Abhinav Kumar (QUIC),
David Airlie, freedreno, Vinod Koul, dri-devel, Stephen Boyd,
Andy Gross, linux-arm-msm, Dmitry Baryshkov,
Aravind Venkateswaran (QUIC),
Bjorn Andersson, Sean Paul, LKML
Hi,
On Mon, Apr 25, 2022 at 10:56 PM Kuogee Hsieh <quic_khsieh@quicinc.com> wrote:
>
> Current DP driver implementation has adding safe mode done at
> dp_hpd_plug_handle() which is expected to be executed under event
> thread context.
>
> However there is possible circular locking happen (see blow stack trace)
> after edp driver call dp_hpd_plug_handle() from dp_bridge_enable() which
> is executed under drm_thread context.
>
> After review all possibilities methods and as discussed on
> https://patchwork.freedesktop.org/patch/483155/, supporting EDID
> compliance tests in the driver is quite hacky. As seen with other
> vendor drivers, supporting these will be much easier with IGT. Hence
> removing all the related fail safe code for it so that no possibility
> of circular lock will happen.
>
> ======================================================
> WARNING: possible circular locking dependency detected
> 5.15.35-lockdep #6 Tainted: G W
> ------------------------------------------------------
> frecon/429 is trying to acquire lock:
> ffffff808dc3c4e8 (&dev->mode_config.mutex){+.+.}-{3:3}, at:
> dp_panel_add_fail_safe_mode+0x4c/0xa0
>
> but task is already holding lock:
> ffffff808dc441e0 (&kms->commit_lock[i]){+.+.}-{3:3}, at: lock_crtcs+0xb4/0x124
>
> which lock already depends on the new lock.
>
> the existing dependency chain (in reverse order) is:
>
> -> #3 (&kms->commit_lock[i]){+.+.}-{3:3}:
> __mutex_lock_common+0x174/0x1a64
> mutex_lock_nested+0x98/0xac
> lock_crtcs+0xb4/0x124
> msm_atomic_commit_tail+0x330/0x748
> commit_tail+0x19c/0x278
> drm_atomic_helper_commit+0x1dc/0x1f0
> drm_atomic_commit+0xc0/0xd8
> drm_atomic_helper_set_config+0xb4/0x134
> drm_mode_setcrtc+0x688/0x1248
> drm_ioctl_kernel+0x1e4/0x338
> drm_ioctl+0x3a4/0x684
> __arm64_sys_ioctl+0x118/0x154
> invoke_syscall+0x78/0x224
> el0_svc_common+0x178/0x200
> do_el0_svc+0x94/0x13c
> el0_svc+0x5c/0xec
> el0t_64_sync_handler+0x78/0x108
> el0t_64_sync+0x1a4/0x1a8
>
> -> #2 (crtc_ww_class_mutex){+.+.}-{3:3}:
> __mutex_lock_common+0x174/0x1a64
> ww_mutex_lock+0xb8/0x278
> modeset_lock+0x304/0x4ac
> drm_modeset_lock+0x4c/0x7c
> drmm_mode_config_init+0x4a8/0xc50
> msm_drm_init+0x274/0xac0
> msm_drm_bind+0x20/0x2c
> try_to_bring_up_master+0x3dc/0x470
> __component_add+0x18c/0x3c0
> component_add+0x1c/0x28
> dp_display_probe+0x954/0xa98
> platform_probe+0x124/0x15c
> really_probe+0x1b0/0x5f8
> __driver_probe_device+0x174/0x20c
> driver_probe_device+0x70/0x134
> __device_attach_driver+0x130/0x1d0
> bus_for_each_drv+0xfc/0x14c
> __device_attach+0x1bc/0x2bc
> device_initial_probe+0x1c/0x28
> bus_probe_device+0x94/0x178
> deferred_probe_work_func+0x1a4/0x1f0
> process_one_work+0x5d4/0x9dc
> worker_thread+0x898/0xccc
> kthread+0x2d4/0x3d4
> ret_from_fork+0x10/0x20
>
> -> #1 (crtc_ww_class_acquire){+.+.}-{0:0}:
> ww_acquire_init+0x1c4/0x2c8
> drm_modeset_acquire_init+0x44/0xc8
> drm_helper_probe_single_connector_modes+0xb0/0x12dc
> drm_mode_getconnector+0x5dc/0xfe8
> drm_ioctl_kernel+0x1e4/0x338
> drm_ioctl+0x3a4/0x684
> __arm64_sys_ioctl+0x118/0x154
> invoke_syscall+0x78/0x224
> el0_svc_common+0x178/0x200
> do_el0_svc+0x94/0x13c
> el0_svc+0x5c/0xec
> el0t_64_sync_handler+0x78/0x108
> el0t_64_sync+0x1a4/0x1a8
>
> -> #0 (&dev->mode_config.mutex){+.+.}-{3:3}:
> __lock_acquire+0x2650/0x672c
> lock_acquire+0x1b4/0x4ac
> __mutex_lock_common+0x174/0x1a64
> mutex_lock_nested+0x98/0xac
> dp_panel_add_fail_safe_mode+0x4c/0xa0
> dp_hpd_plug_handle+0x1f0/0x280
> dp_bridge_enable+0x94/0x2b8
> drm_atomic_bridge_chain_enable+0x11c/0x168
> drm_atomic_helper_commit_modeset_enables+0x500/0x740
> msm_atomic_commit_tail+0x3e4/0x748
> commit_tail+0x19c/0x278
> drm_atomic_helper_commit+0x1dc/0x1f0
> drm_atomic_commit+0xc0/0xd8
> drm_atomic_helper_set_config+0xb4/0x134
> drm_mode_setcrtc+0x688/0x1248
> drm_ioctl_kernel+0x1e4/0x338
> drm_ioctl+0x3a4/0x684
> __arm64_sys_ioctl+0x118/0x154
> invoke_syscall+0x78/0x224
> el0_svc_common+0x178/0x200
> do_el0_svc+0x94/0x13c
> el0_svc+0x5c/0xec
> el0t_64_sync_handler+0x78/0x108
> el0t_64_sync+0x1a4/0x1a8
>
> Changes in v2:
> -- re text commit title
> -- remove all fail safe mode
>
> Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
Reported-by: Douglas Anderson <dianders@chromium.org>
Fixes: f1b47e6a8df8 ("drm/msm/dp: remove fail safe mode related code")
> @@ -151,15 +151,6 @@ static int dp_panel_update_modes(struct drm_connector *connector,
> return rc;
> }
>
> -void dp_panel_add_fail_safe_mode(struct drm_connector *connector)
> -{
> - /* fail safe edid */
> - mutex_lock(&connector->dev->mode_config.mutex);
> - if (drm_add_modes_noedid(connector, 640, 480))
> - drm_set_preferred_mode(connector, 640, 480);
> - mutex_unlock(&connector->dev->mode_config.mutex);
> -}
You removed this function but you forgot to remove it from the header
in "drivers/gpu/drm/msm/dp/dp_panel.h"
-Doug
^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2022-04-26 18:56 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-04-26 5:56 [PATCH v2] drm/msm/dp: remove fail safe mode related code Kuogee Hsieh
2022-04-26 5:56 ` Kuogee Hsieh
2022-04-26 6:00 ` Stephen Boyd
2022-04-26 6:00 ` Stephen Boyd
2022-04-26 17:36 ` Abhinav Kumar
2022-04-26 17:36 ` Abhinav Kumar
2022-04-26 18:48 ` Doug Anderson
2022-04-26 18:48 ` Doug Anderson
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