[PATCH 0/4] drm/msm: properly add and remove internal bridges

[PATCH 0/4] drm/msm: properly add and remove internal bridges

[Dmitry Baryshkov]

While running the kernel with the mutex debugging enabled, I noticed the
warning reported in the first commit (that the bridge's hpd_mutex is
unitialized). Additional research revealed that we do not add and remove
internal drm_bridges in the msm drm driver. Fix this now.

Dmitry Baryshkov (4):
  drm/msm/hdmi: properly add and remove created bridges
  drm/msm/dsi: properly add and remove created bridges
  drm/msm/dp: properly add and remove created bridges
  drm/msm: unregister all internal bridges

 drivers/gpu/drm/msm/dp/dp_drm.c        | 5 +++++
 drivers/gpu/drm/msm/dsi/dsi_manager.c  | 3 +++
 drivers/gpu/drm/msm/hdmi/hdmi_bridge.c | 3 +++
 drivers/gpu/drm/msm/msm_drv.c          | 3 +++
 4 files changed, 14 insertions(+)

-- 
2.35.1

[PATCH 0/4] drm/msm: properly add and remove internal bridges

[Dmitry Baryshkov]

While running the kernel with the mutex debugging enabled, I noticed the
warning reported in the first commit (that the bridge's hpd_mutex is
unitialized). Additional research revealed that we do not add and remove
internal drm_bridges in the msm drm driver. Fix this now.

Dmitry Baryshkov (4):
  drm/msm/hdmi: properly add and remove created bridges
  drm/msm/dsi: properly add and remove created bridges
  drm/msm/dp: properly add and remove created bridges
  drm/msm: unregister all internal bridges

 drivers/gpu/drm/msm/dp/dp_drm.c        | 5 +++++
 drivers/gpu/drm/msm/dsi/dsi_manager.c  | 3 +++
 drivers/gpu/drm/msm/hdmi/hdmi_bridge.c | 3 +++
 drivers/gpu/drm/msm/msm_drv.c          | 3 +++
 4 files changed, 14 insertions(+)

-- 
2.35.1

[PATCH 1/4] drm/msm/hdmi: properly add and remove created bridges

[Dmitry Baryshkov]

Add calls to drm_bridge_add()/drm_bridge_remove() for the internal HDMI
bridges. This fixes the following warning.

[    2.195003] ------------[ cut here ]------------
[    2.195044] WARNING: CPU: 0 PID: 1 at kernel/locking/mutex.c:579 __mutex_lock+0x840/0x9f4
[    2.198774] DEBUG_LOCKS_WARN_ON(lock->magic != lock)
[    2.198786] Modules linked in:
[    2.211868] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.18.0-rc1-00002-g3054695a0d27-dirty #55
[    2.214671] Hardware name: Generic DT based system
[    2.223265]  unwind_backtrace from show_stack+0x10/0x14
[    2.228036]  show_stack from dump_stack_lvl+0x58/0x70
[    2.233159]  dump_stack_lvl from __warn+0xc8/0x1e8
[    2.238367]  __warn from warn_slowpath_fmt+0x78/0xa8
[    2.243054]  warn_slowpath_fmt from __mutex_lock+0x840/0x9f4
[    2.248174]  __mutex_lock from mutex_lock_nested+0x1c/0x24
[    2.253818]  mutex_lock_nested from drm_bridge_hpd_enable+0x2c/0x84
[    2.259116]  drm_bridge_hpd_enable from msm_hdmi_modeset_init+0xc0/0x21c
[    2.265279]  msm_hdmi_modeset_init from mdp4_kms_init+0x53c/0x90c
[    2.272223]  mdp4_kms_init from msm_drm_bind+0x514/0x698
[    2.278212]  msm_drm_bind from try_to_bring_up_aggregate_device+0x160/0x1bc
[    2.283595]  try_to_bring_up_aggregate_device from component_master_add_with_match+0xc4/0xf8
[    2.290281]  component_master_add_with_match from msm_pdev_probe+0x274/0x350
[    2.298958]  msm_pdev_probe from platform_probe+0x5c/0xbc
[    2.305990]  platform_probe from really_probe.part.0+0x9c/0x290
[    2.311284]  really_probe.part.0 from __driver_probe_device+0xa8/0x13c
[    2.317011]  __driver_probe_device from driver_probe_device+0x34/0x10c
[    2.323610]  driver_probe_device from __driver_attach+0xbc/0x178
[    2.330122]  __driver_attach from bus_for_each_dev+0x74/0xc0
[    2.336282]  bus_for_each_dev from bus_add_driver+0x160/0x1e4
[    2.341925]  bus_add_driver from driver_register+0x88/0x118
[    2.347570]  driver_register from do_one_initcall+0x6c/0x334
[    2.352953]  do_one_initcall from kernel_init_freeable+0x1bc/0x220
[    2.358853]  kernel_init_freeable from kernel_init+0x18/0x12c
[    2.364842]  kernel_init from ret_from_fork+0x14/0x2c
[    2.370657] Exception stack(0xf081dfb0 to 0xf081dff8)
[    2.375693] dfa0:                                     00000000 00000000 00000000 00000000
[    2.380733] dfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[    2.388893] dfe0: 00000000 00000000 00000000 00000000 00000013 00000000
[    2.397170] irq event stamp: 202911
[    2.403551] hardirqs last  enabled at (202911): [<c0f86044>] _raw_spin_unlock_irqrestore+0x44/0x48
[    2.406944] hardirqs last disabled at (202910): [<c0f85e18>] _raw_spin_lock_irqsave+0x68/0x6c
[    2.416063] softirqs last  enabled at (202738): [<c03015f0>] __do_softirq+0x2f8/0x530
[    2.424638] softirqs last disabled at (202733): [<c032bc68>] __irq_exit_rcu+0x14c/0x170
[    2.432453] ---[ end trace 0000000000000000 ]---

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 drivers/gpu/drm/msm/hdmi/hdmi_bridge.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/msm/hdmi/hdmi_bridge.c b/drivers/gpu/drm/msm/hdmi/hdmi_bridge.c
index 10ebe2089cb6..97c24010c4d1 100644
--- a/drivers/gpu/drm/msm/hdmi/hdmi_bridge.c
+++ b/drivers/gpu/drm/msm/hdmi/hdmi_bridge.c
@@ -15,6 +15,7 @@ void msm_hdmi_bridge_destroy(struct drm_bridge *bridge)
 	struct hdmi_bridge *hdmi_bridge = to_hdmi_bridge(bridge);
 
 	msm_hdmi_hpd_disable(hdmi_bridge);
+	drm_bridge_remove(bridge);
 }
 
 static void msm_hdmi_power_on(struct drm_bridge *bridge)
@@ -349,6 +350,8 @@ struct drm_bridge *msm_hdmi_bridge_init(struct hdmi *hdmi)
 		DRM_BRIDGE_OP_DETECT |
 		DRM_BRIDGE_OP_EDID;
 
+	drm_bridge_add(bridge);
+
 	ret = drm_bridge_attach(hdmi->encoder, bridge, NULL, DRM_BRIDGE_ATTACH_NO_CONNECTOR);
 	if (ret)
 		goto fail;
-- 
2.35.1

[PATCH 1/4] drm/msm/hdmi: properly add and remove created bridges

[Dmitry Baryshkov]

Add calls to drm_bridge_add()/drm_bridge_remove() for the internal HDMI
bridges. This fixes the following warning.

[    2.195003] ------------[ cut here ]------------
[    2.195044] WARNING: CPU: 0 PID: 1 at kernel/locking/mutex.c:579 __mutex_lock+0x840/0x9f4
[    2.198774] DEBUG_LOCKS_WARN_ON(lock->magic != lock)
[    2.198786] Modules linked in:
[    2.211868] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.18.0-rc1-00002-g3054695a0d27-dirty #55
[    2.214671] Hardware name: Generic DT based system
[    2.223265]  unwind_backtrace from show_stack+0x10/0x14
[    2.228036]  show_stack from dump_stack_lvl+0x58/0x70
[    2.233159]  dump_stack_lvl from __warn+0xc8/0x1e8
[    2.238367]  __warn from warn_slowpath_fmt+0x78/0xa8
[    2.243054]  warn_slowpath_fmt from __mutex_lock+0x840/0x9f4
[    2.248174]  __mutex_lock from mutex_lock_nested+0x1c/0x24
[    2.253818]  mutex_lock_nested from drm_bridge_hpd_enable+0x2c/0x84
[    2.259116]  drm_bridge_hpd_enable from msm_hdmi_modeset_init+0xc0/0x21c
[    2.265279]  msm_hdmi_modeset_init from mdp4_kms_init+0x53c/0x90c
[    2.272223]  mdp4_kms_init from msm_drm_bind+0x514/0x698
[    2.278212]  msm_drm_bind from try_to_bring_up_aggregate_device+0x160/0x1bc
[    2.283595]  try_to_bring_up_aggregate_device from component_master_add_with_match+0xc4/0xf8
[    2.290281]  component_master_add_with_match from msm_pdev_probe+0x274/0x350
[    2.298958]  msm_pdev_probe from platform_probe+0x5c/0xbc
[    2.305990]  platform_probe from really_probe.part.0+0x9c/0x290
[    2.311284]  really_probe.part.0 from __driver_probe_device+0xa8/0x13c
[    2.317011]  __driver_probe_device from driver_probe_device+0x34/0x10c
[    2.323610]  driver_probe_device from __driver_attach+0xbc/0x178
[    2.330122]  __driver_attach from bus_for_each_dev+0x74/0xc0
[    2.336282]  bus_for_each_dev from bus_add_driver+0x160/0x1e4
[    2.341925]  bus_add_driver from driver_register+0x88/0x118
[    2.347570]  driver_register from do_one_initcall+0x6c/0x334
[    2.352953]  do_one_initcall from kernel_init_freeable+0x1bc/0x220
[    2.358853]  kernel_init_freeable from kernel_init+0x18/0x12c
[    2.364842]  kernel_init from ret_from_fork+0x14/0x2c
[    2.370657] Exception stack(0xf081dfb0 to 0xf081dff8)
[    2.375693] dfa0:                                     00000000 00000000 00000000 00000000
[    2.380733] dfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[    2.388893] dfe0: 00000000 00000000 00000000 00000000 00000013 00000000
[    2.397170] irq event stamp: 202911
[    2.403551] hardirqs last  enabled at (202911): [<c0f86044>] _raw_spin_unlock_irqrestore+0x44/0x48
[    2.406944] hardirqs last disabled at (202910): [<c0f85e18>] _raw_spin_lock_irqsave+0x68/0x6c
[    2.416063] softirqs last  enabled at (202738): [<c03015f0>] __do_softirq+0x2f8/0x530
[    2.424638] softirqs last disabled at (202733): [<c032bc68>] __irq_exit_rcu+0x14c/0x170
[    2.432453] ---[ end trace 0000000000000000 ]---

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 drivers/gpu/drm/msm/hdmi/hdmi_bridge.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/msm/hdmi/hdmi_bridge.c b/drivers/gpu/drm/msm/hdmi/hdmi_bridge.c
index 10ebe2089cb6..97c24010c4d1 100644
--- a/drivers/gpu/drm/msm/hdmi/hdmi_bridge.c
+++ b/drivers/gpu/drm/msm/hdmi/hdmi_bridge.c
@@ -15,6 +15,7 @@ void msm_hdmi_bridge_destroy(struct drm_bridge *bridge)
 	struct hdmi_bridge *hdmi_bridge = to_hdmi_bridge(bridge);
 
 	msm_hdmi_hpd_disable(hdmi_bridge);
+	drm_bridge_remove(bridge);
 }
 
 static void msm_hdmi_power_on(struct drm_bridge *bridge)
@@ -349,6 +350,8 @@ struct drm_bridge *msm_hdmi_bridge_init(struct hdmi *hdmi)
 		DRM_BRIDGE_OP_DETECT |
 		DRM_BRIDGE_OP_EDID;
 
+	drm_bridge_add(bridge);
+
 	ret = drm_bridge_attach(hdmi->encoder, bridge, NULL, DRM_BRIDGE_ATTACH_NO_CONNECTOR);
 	if (ret)
 		goto fail;
-- 
2.35.1

[PATCH 2/4] drm/msm/dsi: properly add and remove created bridges

[Dmitry Baryshkov]

Add calls to drm_bridge_add()/drm_bridge_remove() for the internal DSI
bridges.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 drivers/gpu/drm/msm/dsi/dsi_manager.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/msm/dsi/dsi_manager.c b/drivers/gpu/drm/msm/dsi/dsi_manager.c
index 0c1b7dde377c..918498e71255 100644
--- a/drivers/gpu/drm/msm/dsi/dsi_manager.c
+++ b/drivers/gpu/drm/msm/dsi/dsi_manager.c
@@ -665,6 +665,8 @@ struct drm_bridge *msm_dsi_manager_bridge_init(u8 id)
 	bridge = &dsi_bridge->base;
 	bridge->funcs = &dsi_mgr_bridge_funcs;
 
+	drm_bridge_add(bridge);
+
 	ret = drm_bridge_attach(encoder, bridge, NULL, 0);
 	if (ret)
 		goto fail;
@@ -735,6 +737,7 @@ struct drm_connector *msm_dsi_manager_ext_bridge_init(u8 id)
 
 void msm_dsi_manager_bridge_destroy(struct drm_bridge *bridge)
 {
+	drm_bridge_remove(bridge);
 }
 
 int msm_dsi_manager_cmd_xfer(int id, const struct mipi_dsi_msg *msg)
-- 
2.35.1

[PATCH 2/4] drm/msm/dsi: properly add and remove created bridges

[Dmitry Baryshkov]

Add calls to drm_bridge_add()/drm_bridge_remove() for the internal DSI
bridges.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 drivers/gpu/drm/msm/dsi/dsi_manager.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/msm/dsi/dsi_manager.c b/drivers/gpu/drm/msm/dsi/dsi_manager.c
index 0c1b7dde377c..918498e71255 100644
--- a/drivers/gpu/drm/msm/dsi/dsi_manager.c
+++ b/drivers/gpu/drm/msm/dsi/dsi_manager.c
@@ -665,6 +665,8 @@ struct drm_bridge *msm_dsi_manager_bridge_init(u8 id)
 	bridge = &dsi_bridge->base;
 	bridge->funcs = &dsi_mgr_bridge_funcs;
 
+	drm_bridge_add(bridge);
+
 	ret = drm_bridge_attach(encoder, bridge, NULL, 0);
 	if (ret)
 		goto fail;
@@ -735,6 +737,7 @@ struct drm_connector *msm_dsi_manager_ext_bridge_init(u8 id)
 
 void msm_dsi_manager_bridge_destroy(struct drm_bridge *bridge)
 {
+	drm_bridge_remove(bridge);
 }
 
 int msm_dsi_manager_cmd_xfer(int id, const struct mipi_dsi_msg *msg)
-- 
2.35.1

[PATCH 3/4] drm/msm/dp: properly add and remove created bridges

[Dmitry Baryshkov]

Add calls to drm_bridge_add()/drm_bridge_remove() for the internal DP
bridges.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 drivers/gpu/drm/msm/dp/dp_drm.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/msm/dp/dp_drm.c b/drivers/gpu/drm/msm/dp/dp_drm.c
index 80f59cf99089..a7415f9eb80e 100644
--- a/drivers/gpu/drm/msm/dp/dp_drm.c
+++ b/drivers/gpu/drm/msm/dp/dp_drm.c
@@ -230,9 +230,13 @@ struct drm_bridge *msm_dp_bridge_init(struct msm_dp *dp_display, struct drm_devi
 	bridge->funcs = &dp_bridge_ops;
 	bridge->encoder = encoder;
 
+	drm_bridge_add(bridge);
+
 	rc = drm_bridge_attach(encoder, bridge, NULL, DRM_BRIDGE_ATTACH_NO_CONNECTOR);
 	if (rc) {
 		DRM_ERROR("failed to attach bridge, rc=%d\n", rc);
+		drm_bridge_remove(bridge);
+
 		return ERR_PTR(rc);
 	}
 
@@ -242,6 +246,7 @@ struct drm_bridge *msm_dp_bridge_init(struct msm_dp *dp_display, struct drm_devi
 					DRM_BRIDGE_ATTACH_NO_CONNECTOR);
 		if (rc < 0) {
 			DRM_ERROR("failed to attach panel bridge: %d\n", rc);
+			drm_bridge_detach(bridge);
 			drm_bridge_remove(bridge);
 			return ERR_PTR(rc);
 		}
-- 
2.35.1

[PATCH 3/4] drm/msm/dp: properly add and remove created bridges

[Dmitry Baryshkov]

Add calls to drm_bridge_add()/drm_bridge_remove() for the internal DP
bridges.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 drivers/gpu/drm/msm/dp/dp_drm.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/msm/dp/dp_drm.c b/drivers/gpu/drm/msm/dp/dp_drm.c
index 80f59cf99089..a7415f9eb80e 100644
--- a/drivers/gpu/drm/msm/dp/dp_drm.c
+++ b/drivers/gpu/drm/msm/dp/dp_drm.c
@@ -230,9 +230,13 @@ struct drm_bridge *msm_dp_bridge_init(struct msm_dp *dp_display, struct drm_devi
 	bridge->funcs = &dp_bridge_ops;
 	bridge->encoder = encoder;
 
+	drm_bridge_add(bridge);
+
 	rc = drm_bridge_attach(encoder, bridge, NULL, DRM_BRIDGE_ATTACH_NO_CONNECTOR);
 	if (rc) {
 		DRM_ERROR("failed to attach bridge, rc=%d\n", rc);
+		drm_bridge_remove(bridge);
+
 		return ERR_PTR(rc);
 	}
 
@@ -242,6 +246,7 @@ struct drm_bridge *msm_dp_bridge_init(struct msm_dp *dp_display, struct drm_devi
 					DRM_BRIDGE_ATTACH_NO_CONNECTOR);
 		if (rc < 0) {
 			DRM_ERROR("failed to attach panel bridge: %d\n", rc);
+			drm_bridge_detach(bridge);
 			drm_bridge_remove(bridge);
 			return ERR_PTR(rc);
 		}
-- 
2.35.1

[PATCH 4/4] drm/msm: unregister all internal bridges

[Dmitry Baryshkov]

Unwind all drm_bridge_add() calls for internal bridges and remove all
bridges added by the msm driver itself by calling drm_bridge_remove().

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 drivers/gpu/drm/msm/msm_drv.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
index affa95eb05fc..71e1b7393f6f 100644
--- a/drivers/gpu/drm/msm/msm_drv.c
+++ b/drivers/gpu/drm/msm/msm_drv.c
@@ -232,6 +232,9 @@ static int msm_drm_uninit(struct device *dev)
 
 	drm_mode_config_cleanup(ddev);
 
+	for (i = 0; i < priv->num_bridges; i++)
+		drm_bridge_remove(priv->bridges[i]);
+
 	pm_runtime_get_sync(dev);
 	msm_irq_uninstall(ddev);
 	pm_runtime_put_sync(dev);
-- 
2.35.1

[PATCH 4/4] drm/msm: unregister all internal bridges

[Dmitry Baryshkov]

Unwind all drm_bridge_add() calls for internal bridges and remove all
bridges added by the msm driver itself by calling drm_bridge_remove().

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 drivers/gpu/drm/msm/msm_drv.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
index affa95eb05fc..71e1b7393f6f 100644
--- a/drivers/gpu/drm/msm/msm_drv.c
+++ b/drivers/gpu/drm/msm/msm_drv.c
@@ -232,6 +232,9 @@ static int msm_drm_uninit(struct device *dev)
 
 	drm_mode_config_cleanup(ddev);
 
+	for (i = 0; i < priv->num_bridges; i++)
+		drm_bridge_remove(priv->bridges[i]);
+
 	pm_runtime_get_sync(dev);
 	msm_irq_uninstall(ddev);
 	pm_runtime_put_sync(dev);
-- 
2.35.1

Re: [PATCH 1/4] drm/msm/hdmi: properly add and remove created bridges

[Stephen Boyd]

Quoting Dmitry Baryshkov (2022-04-05 16:45:48)
> Add calls to drm_bridge_add()/drm_bridge_remove() for the internal HDMI
> bridges. This fixes the following warning.
>
> [    2.195003] ------------[ cut here ]------------

Usually this line is left out

> [    2.195044] WARNING: CPU: 0 PID: 1 at kernel/locking/mutex.c:579 __mutex_lock+0x840/0x9f4

And the timestamp is removed

> [    2.198774] DEBUG_LOCKS_WARN_ON(lock->magic != lock)
> [    2.198786] Modules linked in:
> [    2.211868] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.18.0-rc1-00002-g3054695a0d27-dirty #55
> [    2.214671] Hardware name: Generic DT based system
> [    2.223265]  unwind_backtrace from show_stack+0x10/0x14
> [    2.228036]  show_stack from dump_stack_lvl+0x58/0x70
> [    2.233159]  dump_stack_lvl from __warn+0xc8/0x1e8
> [    2.238367]  __warn from warn_slowpath_fmt+0x78/0xa8
> [    2.243054]  warn_slowpath_fmt from __mutex_lock+0x840/0x9f4
> [    2.248174]  __mutex_lock from mutex_lock_nested+0x1c/0x24
> [    2.253818]  mutex_lock_nested from drm_bridge_hpd_enable+0x2c/0x84
> [    2.259116]  drm_bridge_hpd_enable from msm_hdmi_modeset_init+0xc0/0x21c
> [    2.265279]  msm_hdmi_modeset_init from mdp4_kms_init+0x53c/0x90c
> [    2.272223]  mdp4_kms_init from msm_drm_bind+0x514/0x698
> [    2.278212]  msm_drm_bind from try_to_bring_up_aggregate_device+0x160/0x1bc

I'd probably cut it off here.

Is there any Fixes tag for this? Still seems worthwhile to have one even
if this is a lockdep warning.

Re: [PATCH 1/4] drm/msm/hdmi: properly add and remove created bridges

[Stephen Boyd]

Quoting Dmitry Baryshkov (2022-04-05 16:45:48)
> Add calls to drm_bridge_add()/drm_bridge_remove() for the internal HDMI
> bridges. This fixes the following warning.
>
> [    2.195003] ------------[ cut here ]------------

Usually this line is left out

> [    2.195044] WARNING: CPU: 0 PID: 1 at kernel/locking/mutex.c:579 __mutex_lock+0x840/0x9f4

And the timestamp is removed

> [    2.198774] DEBUG_LOCKS_WARN_ON(lock->magic != lock)
> [    2.198786] Modules linked in:
> [    2.211868] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.18.0-rc1-00002-g3054695a0d27-dirty #55
> [    2.214671] Hardware name: Generic DT based system
> [    2.223265]  unwind_backtrace from show_stack+0x10/0x14
> [    2.228036]  show_stack from dump_stack_lvl+0x58/0x70
> [    2.233159]  dump_stack_lvl from __warn+0xc8/0x1e8
> [    2.238367]  __warn from warn_slowpath_fmt+0x78/0xa8
> [    2.243054]  warn_slowpath_fmt from __mutex_lock+0x840/0x9f4
> [    2.248174]  __mutex_lock from mutex_lock_nested+0x1c/0x24
> [    2.253818]  mutex_lock_nested from drm_bridge_hpd_enable+0x2c/0x84
> [    2.259116]  drm_bridge_hpd_enable from msm_hdmi_modeset_init+0xc0/0x21c
> [    2.265279]  msm_hdmi_modeset_init from mdp4_kms_init+0x53c/0x90c
> [    2.272223]  mdp4_kms_init from msm_drm_bind+0x514/0x698
> [    2.278212]  msm_drm_bind from try_to_bring_up_aggregate_device+0x160/0x1bc

I'd probably cut it off here.

Is there any Fixes tag for this? Still seems worthwhile to have one even
if this is a lockdep warning.

Re: [PATCH 1/4] drm/msm/hdmi: properly add and remove created bridges

[Dmitry Baryshkov]

On 06/04/2022 05:51, Stephen Boyd wrote:
> Quoting Dmitry Baryshkov (2022-04-05 16:45:48)
>> Add calls to drm_bridge_add()/drm_bridge_remove() for the internal HDMI
>> bridges. This fixes the following warning.
>>
>> [    2.195003] ------------[ cut here ]------------
> 
> Usually this line is left out
> 
>> [    2.195044] WARNING: CPU: 0 PID: 1 at kernel/locking/mutex.c:579 __mutex_lock+0x840/0x9f4
> 
> And the timestamp is removed

Ack for both notes, will fix in v2

> 
>> [    2.198774] DEBUG_LOCKS_WARN_ON(lock->magic != lock)
>> [    2.198786] Modules linked in:
>> [    2.211868] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.18.0-rc1-00002-g3054695a0d27-dirty #55
>> [    2.214671] Hardware name: Generic DT based system
>> [    2.223265]  unwind_backtrace from show_stack+0x10/0x14
>> [    2.228036]  show_stack from dump_stack_lvl+0x58/0x70
>> [    2.233159]  dump_stack_lvl from __warn+0xc8/0x1e8
>> [    2.238367]  __warn from warn_slowpath_fmt+0x78/0xa8
>> [    2.243054]  warn_slowpath_fmt from __mutex_lock+0x840/0x9f4
>> [    2.248174]  __mutex_lock from mutex_lock_nested+0x1c/0x24
>> [    2.253818]  mutex_lock_nested from drm_bridge_hpd_enable+0x2c/0x84
>> [    2.259116]  drm_bridge_hpd_enable from msm_hdmi_modeset_init+0xc0/0x21c
>> [    2.265279]  msm_hdmi_modeset_init from mdp4_kms_init+0x53c/0x90c
>> [    2.272223]  mdp4_kms_init from msm_drm_bind+0x514/0x698
>> [    2.278212]  msm_drm_bind from try_to_bring_up_aggregate_device+0x160/0x1bc
> 
> I'd probably cut it off here.

ack

> 
> Is there any Fixes tag for this? Still seems worthwhile to have one even
> if this is a lockdep warning.
I thought about this before sending v1, but ended up not doing so. Each 
of these changes is not atomic. A call to drm_bridge_add() without final 
drm_bridge_remove() in the core msm code would leave dangling pointers 
in the drm core. A drm_bridge_remove() is not sensible without 
converting _all_ users.

So there are two alternatives:
- leave this patch series as is w/o a Fixes tag
- squash four patches into a single patch and add 'Fixes: a3376e3ec81c 
("drm/msm: convert to drm_bridge")' tag

What would you prefer?

-- 
With best wishes
Dmitry

Re: [PATCH 1/4] drm/msm/hdmi: properly add and remove created bridges

[Dmitry Baryshkov]

On 06/04/2022 05:51, Stephen Boyd wrote:
> Quoting Dmitry Baryshkov (2022-04-05 16:45:48)
>> Add calls to drm_bridge_add()/drm_bridge_remove() for the internal HDMI
>> bridges. This fixes the following warning.
>>
>> [    2.195003] ------------[ cut here ]------------
> 
> Usually this line is left out
> 
>> [    2.195044] WARNING: CPU: 0 PID: 1 at kernel/locking/mutex.c:579 __mutex_lock+0x840/0x9f4
> 
> And the timestamp is removed

Ack for both notes, will fix in v2

> 
>> [    2.198774] DEBUG_LOCKS_WARN_ON(lock->magic != lock)
>> [    2.198786] Modules linked in:
>> [    2.211868] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.18.0-rc1-00002-g3054695a0d27-dirty #55
>> [    2.214671] Hardware name: Generic DT based system
>> [    2.223265]  unwind_backtrace from show_stack+0x10/0x14
>> [    2.228036]  show_stack from dump_stack_lvl+0x58/0x70
>> [    2.233159]  dump_stack_lvl from __warn+0xc8/0x1e8
>> [    2.238367]  __warn from warn_slowpath_fmt+0x78/0xa8
>> [    2.243054]  warn_slowpath_fmt from __mutex_lock+0x840/0x9f4
>> [    2.248174]  __mutex_lock from mutex_lock_nested+0x1c/0x24
>> [    2.253818]  mutex_lock_nested from drm_bridge_hpd_enable+0x2c/0x84
>> [    2.259116]  drm_bridge_hpd_enable from msm_hdmi_modeset_init+0xc0/0x21c
>> [    2.265279]  msm_hdmi_modeset_init from mdp4_kms_init+0x53c/0x90c
>> [    2.272223]  mdp4_kms_init from msm_drm_bind+0x514/0x698
>> [    2.278212]  msm_drm_bind from try_to_bring_up_aggregate_device+0x160/0x1bc
> 
> I'd probably cut it off here.

ack

> 
> Is there any Fixes tag for this? Still seems worthwhile to have one even
> if this is a lockdep warning.
I thought about this before sending v1, but ended up not doing so. Each 
of these changes is not atomic. A call to drm_bridge_add() without final 
drm_bridge_remove() in the core msm code would leave dangling pointers 
in the drm core. A drm_bridge_remove() is not sensible without 
converting _all_ users.

So there are two alternatives:
- leave this patch series as is w/o a Fixes tag
- squash four patches into a single patch and add 'Fixes: a3376e3ec81c 
("drm/msm: convert to drm_bridge")' tag

What would you prefer?

-- 
With best wishes
Dmitry

Re: [PATCH 1/4] drm/msm/hdmi: properly add and remove created bridges

[Stephen Boyd]

Quoting Dmitry Baryshkov (2022-04-06 03:21:25)
> On 06/04/2022 05:51, Stephen Boyd wrote:
> >
> > Is there any Fixes tag for this? Still seems worthwhile to have one even
> > if this is a lockdep warning.
> I thought about this before sending v1, but ended up not doing so. Each
> of these changes is not atomic. A call to drm_bridge_add() without final
> drm_bridge_remove() in the core msm code would leave dangling pointers
> in the drm core. A drm_bridge_remove() is not sensible without
> converting _all_ users.
>
> So there are two alternatives:
> - leave this patch series as is w/o a Fixes tag
> - squash four patches into a single patch and add 'Fixes: a3376e3ec81c
> ("drm/msm: convert to drm_bridge")' tag
>

The atomic change. That's because bisection could trip over these
patches and then break because it picked the middle of the patch series.
One atomic commit fixes that.

Re: [PATCH 1/4] drm/msm/hdmi: properly add and remove created bridges

[Stephen Boyd]

Quoting Dmitry Baryshkov (2022-04-06 03:21:25)
> On 06/04/2022 05:51, Stephen Boyd wrote:
> >
> > Is there any Fixes tag for this? Still seems worthwhile to have one even
> > if this is a lockdep warning.
> I thought about this before sending v1, but ended up not doing so. Each
> of these changes is not atomic. A call to drm_bridge_add() without final
> drm_bridge_remove() in the core msm code would leave dangling pointers
> in the drm core. A drm_bridge_remove() is not sensible without
> converting _all_ users.
>
> So there are two alternatives:
> - leave this patch series as is w/o a Fixes tag
> - squash four patches into a single patch and add 'Fixes: a3376e3ec81c
> ("drm/msm: convert to drm_bridge")' tag
>

The atomic change. That's because bisection could trip over these
patches and then break because it picked the middle of the patch series.
One atomic commit fixes that.