[PATCH 3/6] soc: qcom: pmic_glink_altmode: fix drm bridge use-after-free

[PATCH 3/6] soc: qcom: pmic_glink_altmode: fix drm bridge use-after-free

[Johan Hovold]

A recent DRM series purporting to simplify support for "transparent
bridges" and handling of probe deferrals ironically exposed a
use-after-free issue on pmic_glink_altmode probe deferral.

This has manifested itself as the display subsystem occasionally failing
to initialise and NULL-pointer dereferences during boot of machines like
the Lenovo ThinkPad X13s.

Specifically, the dp-hpd bridge is currently registered before all
resources have been acquired which means that it can also be
deregistered on probe deferrals.

In the meantime there is a race window where the new aux bridge driver
(or PHY driver previously) may have looked up the dp-hpd bridge and
stored a (non-reference-counted) pointer to the bridge which is about to
be deallocated.

When the display controller is later initialised, this triggers a
use-after-free when attaching the bridges:

	dp -> aux -> dp-hpd (freed)

which may, for example, result in the freed bridge failing to attach:

	[drm:drm_bridge_attach [drm]] *ERROR* failed to attach bridge /soc@0/phy@88eb000 to encoder TMDS-31: -16

or a NULL-pointer dereference:

	Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
	...
	Call trace:
	  drm_bridge_attach+0x70/0x1a8 [drm]
	  drm_aux_bridge_attach+0x24/0x38 [aux_bridge]
	  drm_bridge_attach+0x80/0x1a8 [drm]
	  dp_bridge_init+0xa8/0x15c [msm]
	  msm_dp_modeset_init+0x28/0xc4 [msm]

The DRM bridge implementation is clearly fragile and implicitly built on
the assumption that bridges may never go away. In this case, the fix is
to move the bridge registration in the pmic_glink_altmode driver to
after all resources have been looked up.

Incidentally, with the new dp-hpd bridge implementation, which registers
child devices, this is also a requirement due to a long-standing issue
in driver core that can otherwise lead to a probe deferral loop (see
fbc35b45f9f6 ("Add documentation on meaning of -EPROBE_DEFER")).

Fixes: 080b4e24852b ("soc: qcom: pmic_glink: Introduce altmode support")
Fixes: 2bcca96abfbf ("soc: qcom: pmic-glink: switch to DRM_AUX_HPD_BRIDGE")
Cc: stable@vger.kernel.org      # 6.3
Cc: Bjorn Andersson <andersson@kernel.org>
Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
---
 drivers/soc/qcom/pmic_glink_altmode.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/soc/qcom/pmic_glink_altmode.c b/drivers/soc/qcom/pmic_glink_altmode.c
index 5fcd0fdd2faa..b3808fc24c69 100644
--- a/drivers/soc/qcom/pmic_glink_altmode.c
+++ b/drivers/soc/qcom/pmic_glink_altmode.c
@@ -76,7 +76,7 @@ struct pmic_glink_altmode_port {
 
 	struct work_struct work;
 
-	struct device *bridge;
+	struct auxiliary_device *bridge;
 
 	enum typec_orientation orientation;
 	u16 svid;
@@ -230,7 +230,7 @@ static void pmic_glink_altmode_worker(struct work_struct *work)
 	else
 		pmic_glink_altmode_enable_usb(altmode, alt_port);
 
-	drm_aux_hpd_bridge_notify(alt_port->bridge,
+	drm_aux_hpd_bridge_notify(&alt_port->bridge->dev,
 				  alt_port->hpd_state ?
 				  connector_status_connected :
 				  connector_status_disconnected);
@@ -454,7 +454,7 @@ static int pmic_glink_altmode_probe(struct auxiliary_device *adev,
 		alt_port->index = port;
 		INIT_WORK(&alt_port->work, pmic_glink_altmode_worker);
 
-		alt_port->bridge = drm_dp_hpd_bridge_register(dev, to_of_node(fwnode));
+		alt_port->bridge = devm_drm_dp_hpd_bridge_alloc(dev, to_of_node(fwnode));
 		if (IS_ERR(alt_port->bridge)) {
 			fwnode_handle_put(fwnode);
 			return PTR_ERR(alt_port->bridge);
@@ -510,6 +510,16 @@ static int pmic_glink_altmode_probe(struct auxiliary_device *adev,
 		}
 	}
 
+	for (port = 0; port < ARRAY_SIZE(altmode->ports); port++) {
+		alt_port = &altmode->ports[port];
+		if (!alt_port->bridge)
+			continue;
+
+		ret = devm_drm_dp_hpd_bridge_add(dev, alt_port->bridge);
+		if (ret)
+			return ret;
+	}
+
 	altmode->client = devm_pmic_glink_register_client(dev,
 							  altmode->owner_id,
 							  pmic_glink_altmode_callback,
-- 
2.43.0

Re: [PATCH 3/6] soc: qcom: pmic_glink_altmode: fix drm bridge use-after-free

[Markus Elfring]

…
> Specifically, the dp-hpd bridge is currently registered before all
> resources have been acquired which means that it can also be
> deregistered on probe deferrals.
>
> In the meantime there is a race window where the new aux bridge driver
> (or PHY driver previously) may have looked up the dp-hpd bridge and
> stored a (non-reference-counted) pointer to the bridge which is about to
> be deallocated.
…

I got the impression that the change description can be improved another bit.

1. Will any additional imperative wordings become helpful?
   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?h=v6.8-rc5#n94


…
> +++ b/drivers/soc/qcom/pmic_glink_altmode.c
> @@ -76,7 +76,7 @@ struct pmic_glink_altmode_port {
>
>  	struct work_struct work;
>
> -	struct device *bridge;
> +	struct auxiliary_device *bridge;
>
>  	enum typec_orientation orientation;
>  	u16 svid;
…

2. How do you think about to stress such a data type adjustment?

Regards,
Markus

Re: [PATCH 3/6] soc: qcom: pmic_glink_altmode: fix drm bridge use-after-free

[Markus Elfring]

…
> Specifically, the dp-hpd bridge is currently registered before all
> resources have been acquired which means that it can also be
> deregistered on probe deferrals.
>
> In the meantime there is a race window where the new aux bridge driver
> (or PHY driver previously) may have looked up the dp-hpd bridge and
> stored a (non-reference-counted) pointer to the bridge which is about to
> be deallocated.
…
> +++ b/drivers/soc/qcom/pmic_glink_altmode.c
…
> @@ -454,7 +454,7 @@ static int pmic_glink_altmode_probe(struct auxiliary_device *adev,
>  		alt_port->index = port;
>  		INIT_WORK(&alt_port->work, pmic_glink_altmode_worker);
>
> -		alt_port->bridge = drm_dp_hpd_bridge_register(dev, to_of_node(fwnode));
> +		alt_port->bridge = devm_drm_dp_hpd_bridge_alloc(dev, to_of_node(fwnode));
>  		if (IS_ERR(alt_port->bridge)) {
>  			fwnode_handle_put(fwnode);
>  			return PTR_ERR(alt_port->bridge);
…

The function call “fwnode_handle_put(fwnode)” is used in multiple if branches.
https://elixir.bootlin.com/linux/v6.8-rc5/source/drivers/soc/qcom/pmic_glink_altmode.c#L435

I suggest to add a jump target so that a bit of exception handling
can be better reused at the end of this function implementation.

Regards,
Markus

Re: [PATCH 3/6] soc: qcom: pmic_glink_altmode: fix drm bridge use-after-free

[Johan Hovold]

On Tue, Feb 20, 2024 at 11:55:57AM +0100, Markus Elfring wrote:
> …
> > Specifically, the dp-hpd bridge is currently registered before all
> > resources have been acquired which means that it can also be
> > deregistered on probe deferrals.
> >
> > In the meantime there is a race window where the new aux bridge driver
> > (or PHY driver previously) may have looked up the dp-hpd bridge and
> > stored a (non-reference-counted) pointer to the bridge which is about to
> > be deallocated.
> …
> > +++ b/drivers/soc/qcom/pmic_glink_altmode.c
> …
> > @@ -454,7 +454,7 @@ static int pmic_glink_altmode_probe(struct auxiliary_device *adev,
> >  		alt_port->index = port;
> >  		INIT_WORK(&alt_port->work, pmic_glink_altmode_worker);
> >
> > -		alt_port->bridge = drm_dp_hpd_bridge_register(dev, to_of_node(fwnode));
> > +		alt_port->bridge = devm_drm_dp_hpd_bridge_alloc(dev, to_of_node(fwnode));
> >  		if (IS_ERR(alt_port->bridge)) {
> >  			fwnode_handle_put(fwnode);
> >  			return PTR_ERR(alt_port->bridge);
> …
> 
> The function call “fwnode_handle_put(fwnode)” is used in multiple if branches.
> https://elixir.bootlin.com/linux/v6.8-rc5/source/drivers/soc/qcom/pmic_glink_altmode.c#L435
> 
> I suggest to add a jump target so that a bit of exception handling
> can be better reused at the end of this function implementation.

Markus, as people have told you repeatedly, just stop with these
comments. You're not helping, in fact, you are actively harmful to the
kernel community as you are wasting people's time.

Johan

Re: [3/6] soc: qcom: pmic_glink_altmode: fix drm bridge use-after-free

[Markus Elfring]

>> The function call “fwnode_handle_put(fwnode)” is used in multiple if branches.
>> https://elixir.bootlin.com/linux/v6.8-rc5/source/drivers/soc/qcom/pmic_glink_altmode.c#L435
>>
>> I suggest to add a jump target so that a bit of exception handling
>> can be better reused at the end of this function implementation.
>
> Markus, as people have told you repeatedly, just stop with these comments.

How does such a response fit to advices from another known information sources?

Section “7) Centralized exiting of functions”
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/coding-style.rst?h=v6.8-rc5#n526


> You're not helping, in fact, you are actively harmful to the
> kernel community as you are wasting people's time.

The proposed source code transformation can eventually be (automatically) achieved
also with help of improved development tools.

Regards,
Markus

Re: [PATCH 3/6] soc: qcom: pmic_glink_altmode: fix drm bridge use-after-free

[Bjorn Andersson]

On Sat, Feb 17, 2024 at 04:02:25PM +0100, Johan Hovold wrote:
> A recent DRM series purporting to simplify support for "transparent
> bridges" and handling of probe deferrals ironically exposed a
> use-after-free issue on pmic_glink_altmode probe deferral.
> 
> This has manifested itself as the display subsystem occasionally failing
> to initialise and NULL-pointer dereferences during boot of machines like
> the Lenovo ThinkPad X13s.
> 
> Specifically, the dp-hpd bridge is currently registered before all
> resources have been acquired which means that it can also be
> deregistered on probe deferrals.
> 
> In the meantime there is a race window where the new aux bridge driver
> (or PHY driver previously) may have looked up the dp-hpd bridge and
> stored a (non-reference-counted) pointer to the bridge which is about to
> be deallocated.
> 
> When the display controller is later initialised, this triggers a
> use-after-free when attaching the bridges:
> 
> 	dp -> aux -> dp-hpd (freed)
> 
> which may, for example, result in the freed bridge failing to attach:
> 
> 	[drm:drm_bridge_attach [drm]] *ERROR* failed to attach bridge /soc@0/phy@88eb000 to encoder TMDS-31: -16
> 
> or a NULL-pointer dereference:
> 
> 	Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
> 	...
> 	Call trace:
> 	  drm_bridge_attach+0x70/0x1a8 [drm]
> 	  drm_aux_bridge_attach+0x24/0x38 [aux_bridge]
> 	  drm_bridge_attach+0x80/0x1a8 [drm]
> 	  dp_bridge_init+0xa8/0x15c [msm]
> 	  msm_dp_modeset_init+0x28/0xc4 [msm]
> 
> The DRM bridge implementation is clearly fragile and implicitly built on
> the assumption that bridges may never go away. In this case, the fix is
> to move the bridge registration in the pmic_glink_altmode driver to
> after all resources have been looked up.
> 
> Incidentally, with the new dp-hpd bridge implementation, which registers
> child devices, this is also a requirement due to a long-standing issue
> in driver core that can otherwise lead to a probe deferral loop (see
> fbc35b45f9f6 ("Add documentation on meaning of -EPROBE_DEFER")).
> 
> Fixes: 080b4e24852b ("soc: qcom: pmic_glink: Introduce altmode support")
> Fixes: 2bcca96abfbf ("soc: qcom: pmic-glink: switch to DRM_AUX_HPD_BRIDGE")
> Cc: stable@vger.kernel.org      # 6.3
> Cc: Bjorn Andersson <andersson@kernel.org>
> Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>

Reviewed-by: Bjorn Andersson <andersson@kernel.org>

Regards,
Bjorn

> ---
>  drivers/soc/qcom/pmic_glink_altmode.c | 16 +++++++++++++---
>  1 file changed, 13 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/soc/qcom/pmic_glink_altmode.c b/drivers/soc/qcom/pmic_glink_altmode.c
> index 5fcd0fdd2faa..b3808fc24c69 100644
> --- a/drivers/soc/qcom/pmic_glink_altmode.c
> +++ b/drivers/soc/qcom/pmic_glink_altmode.c
> @@ -76,7 +76,7 @@ struct pmic_glink_altmode_port {
>  
>  	struct work_struct work;
>  
> -	struct device *bridge;
> +	struct auxiliary_device *bridge;
>  
>  	enum typec_orientation orientation;
>  	u16 svid;
> @@ -230,7 +230,7 @@ static void pmic_glink_altmode_worker(struct work_struct *work)
>  	else
>  		pmic_glink_altmode_enable_usb(altmode, alt_port);
>  
> -	drm_aux_hpd_bridge_notify(alt_port->bridge,
> +	drm_aux_hpd_bridge_notify(&alt_port->bridge->dev,
>  				  alt_port->hpd_state ?
>  				  connector_status_connected :
>  				  connector_status_disconnected);
> @@ -454,7 +454,7 @@ static int pmic_glink_altmode_probe(struct auxiliary_device *adev,
>  		alt_port->index = port;
>  		INIT_WORK(&alt_port->work, pmic_glink_altmode_worker);
>  
> -		alt_port->bridge = drm_dp_hpd_bridge_register(dev, to_of_node(fwnode));
> +		alt_port->bridge = devm_drm_dp_hpd_bridge_alloc(dev, to_of_node(fwnode));
>  		if (IS_ERR(alt_port->bridge)) {
>  			fwnode_handle_put(fwnode);
>  			return PTR_ERR(alt_port->bridge);
> @@ -510,6 +510,16 @@ static int pmic_glink_altmode_probe(struct auxiliary_device *adev,
>  		}
>  	}
>  
> +	for (port = 0; port < ARRAY_SIZE(altmode->ports); port++) {
> +		alt_port = &altmode->ports[port];
> +		if (!alt_port->bridge)
> +			continue;
> +
> +		ret = devm_drm_dp_hpd_bridge_add(dev, alt_port->bridge);
> +		if (ret)
> +			return ret;
> +	}
> +
>  	altmode->client = devm_pmic_glink_register_client(dev,
>  							  altmode->owner_id,
>  							  pmic_glink_altmode_callback,
> -- 
> 2.43.0
> 

Re: [PATCH 3/6] soc: qcom: pmic_glink_altmode: fix drm bridge use-after-free

[Dmitry Baryshkov]

On Sat, 17 Feb 2024 at 17:03, Johan Hovold <johan+linaro@kernel.org> wrote:
>
> A recent DRM series purporting to simplify support for "transparent
> bridges" and handling of probe deferrals ironically exposed a
> use-after-free issue on pmic_glink_altmode probe deferral.
>
> This has manifested itself as the display subsystem occasionally failing
> to initialise and NULL-pointer dereferences during boot of machines like
> the Lenovo ThinkPad X13s.
>
> Specifically, the dp-hpd bridge is currently registered before all
> resources have been acquired which means that it can also be
> deregistered on probe deferrals.
>
> In the meantime there is a race window where the new aux bridge driver
> (or PHY driver previously) may have looked up the dp-hpd bridge and
> stored a (non-reference-counted) pointer to the bridge which is about to
> be deallocated.
>
> When the display controller is later initialised, this triggers a
> use-after-free when attaching the bridges:
>
>         dp -> aux -> dp-hpd (freed)
>
> which may, for example, result in the freed bridge failing to attach:
>
>         [drm:drm_bridge_attach [drm]] *ERROR* failed to attach bridge /soc@0/phy@88eb000 to encoder TMDS-31: -16
>
> or a NULL-pointer dereference:
>
>         Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
>         ...
>         Call trace:
>           drm_bridge_attach+0x70/0x1a8 [drm]
>           drm_aux_bridge_attach+0x24/0x38 [aux_bridge]
>           drm_bridge_attach+0x80/0x1a8 [drm]
>           dp_bridge_init+0xa8/0x15c [msm]
>           msm_dp_modeset_init+0x28/0xc4 [msm]
>
> The DRM bridge implementation is clearly fragile and implicitly built on
> the assumption that bridges may never go away. In this case, the fix is
> to move the bridge registration in the pmic_glink_altmode driver to
> after all resources have been looked up.
>
> Incidentally, with the new dp-hpd bridge implementation, which registers
> child devices, this is also a requirement due to a long-standing issue
> in driver core that can otherwise lead to a probe deferral loop (see
> fbc35b45f9f6 ("Add documentation on meaning of -EPROBE_DEFER")).
>
> Fixes: 080b4e24852b ("soc: qcom: pmic_glink: Introduce altmode support")
> Fixes: 2bcca96abfbf ("soc: qcom: pmic-glink: switch to DRM_AUX_HPD_BRIDGE")
> Cc: stable@vger.kernel.org      # 6.3
> Cc: Bjorn Andersson <andersson@kernel.org>
> Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
> ---
>  drivers/soc/qcom/pmic_glink_altmode.c | 16 +++++++++++++---
>  1 file changed, 13 insertions(+), 3 deletions(-)
>

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>


-- 
With best wishes
Dmitry

[PATCH 4/6] soc: qcom: pmic_glink: Fix boot when QRTR=m

[Johan Hovold]

From: Rob Clark <robdclark@chromium.org>

We need to bail out before adding/removing devices if we are going to
-EPROBE_DEFER. Otherwise boot can get stuck in a probe deferral loop due
to a long-standing issue in driver core (see fbc35b45f9f6 ("Add
documentation on meaning of -EPROBE_DEFER")).

Deregistering the altmode child device can potentially also trigger bugs
in the DRM bridge implementation, which does not expect bridges to go
away.

Suggested-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>
Link: https://lore.kernel.org/r/20231213210644.8702-1-robdclark@gmail.com
[ johan: rebase on 6.8-rc4, amend commit message and mention DRM ]
Fixes: 58ef4ece1e41 ("soc: qcom: pmic_glink: Introduce base PMIC GLINK driver")
Cc: stable@vger.kernel.org      # 6.3
Cc: Bjorn Andersson <andersson@kernel.org>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
---
 drivers/soc/qcom/pmic_glink.c | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/drivers/soc/qcom/pmic_glink.c b/drivers/soc/qcom/pmic_glink.c
index f4bfd24386f1..f913e9bd57ed 100644
--- a/drivers/soc/qcom/pmic_glink.c
+++ b/drivers/soc/qcom/pmic_glink.c
@@ -265,10 +265,17 @@ static int pmic_glink_probe(struct platform_device *pdev)
 
 	pg->client_mask = *match_data;
 
+	pg->pdr = pdr_handle_alloc(pmic_glink_pdr_callback, pg);
+	if (IS_ERR(pg->pdr)) {
+		ret = dev_err_probe(&pdev->dev, PTR_ERR(pg->pdr),
+				    "failed to initialize pdr\n");
+		return ret;
+	}
+
 	if (pg->client_mask & BIT(PMIC_GLINK_CLIENT_UCSI)) {
 		ret = pmic_glink_add_aux_device(pg, &pg->ucsi_aux, "ucsi");
 		if (ret)
-			return ret;
+			goto out_release_pdr_handle;
 	}
 	if (pg->client_mask & BIT(PMIC_GLINK_CLIENT_ALTMODE)) {
 		ret = pmic_glink_add_aux_device(pg, &pg->altmode_aux, "altmode");
@@ -281,17 +288,11 @@ static int pmic_glink_probe(struct platform_device *pdev)
 			goto out_release_altmode_aux;
 	}
 
-	pg->pdr = pdr_handle_alloc(pmic_glink_pdr_callback, pg);
-	if (IS_ERR(pg->pdr)) {
-		ret = dev_err_probe(&pdev->dev, PTR_ERR(pg->pdr), "failed to initialize pdr\n");
-		goto out_release_aux_devices;
-	}
-
 	service = pdr_add_lookup(pg->pdr, "tms/servreg", "msm/adsp/charger_pd");
 	if (IS_ERR(service)) {
 		ret = dev_err_probe(&pdev->dev, PTR_ERR(service),
 				    "failed adding pdr lookup for charger_pd\n");
-		goto out_release_pdr_handle;
+		goto out_release_aux_devices;
 	}
 
 	mutex_lock(&__pmic_glink_lock);
@@ -300,8 +301,6 @@ static int pmic_glink_probe(struct platform_device *pdev)
 
 	return 0;
 
-out_release_pdr_handle:
-	pdr_handle_release(pg->pdr);
 out_release_aux_devices:
 	if (pg->client_mask & BIT(PMIC_GLINK_CLIENT_BATT))
 		pmic_glink_del_aux_device(pg, &pg->ps_aux);
@@ -311,6 +310,8 @@ static int pmic_glink_probe(struct platform_device *pdev)
 out_release_ucsi_aux:
 	if (pg->client_mask & BIT(PMIC_GLINK_CLIENT_UCSI))
 		pmic_glink_del_aux_device(pg, &pg->ucsi_aux);
+out_release_pdr_handle:
+	pdr_handle_release(pg->pdr);
 
 	return ret;
 }
-- 
2.43.0

Re: [PATCH 4/6] soc: qcom: pmic_glink: Fix boot when QRTR=m

[Bjorn Andersson]

On Sat, Feb 17, 2024 at 04:02:26PM +0100, Johan Hovold wrote:
> From: Rob Clark <robdclark@chromium.org>
> 
> We need to bail out before adding/removing devices if we are going to
> -EPROBE_DEFER. Otherwise boot can get stuck in a probe deferral loop due
> to a long-standing issue in driver core (see fbc35b45f9f6 ("Add
> documentation on meaning of -EPROBE_DEFER")).
> 
> Deregistering the altmode child device can potentially also trigger bugs
> in the DRM bridge implementation, which does not expect bridges to go
> away.
> 
> Suggested-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> Signed-off-by: Rob Clark <robdclark@chromium.org>
> Link: https://lore.kernel.org/r/20231213210644.8702-1-robdclark@gmail.com
> [ johan: rebase on 6.8-rc4, amend commit message and mention DRM ]
> Fixes: 58ef4ece1e41 ("soc: qcom: pmic_glink: Introduce base PMIC GLINK driver")
> Cc: stable@vger.kernel.org      # 6.3
> Cc: Bjorn Andersson <andersson@kernel.org>
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>

Reviewed-by: Bjorn Andersson <andersson@kernel.org>

Regards,
Bjorn

> ---
>  drivers/soc/qcom/pmic_glink.c | 21 +++++++++++----------
>  1 file changed, 11 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/soc/qcom/pmic_glink.c b/drivers/soc/qcom/pmic_glink.c
> index f4bfd24386f1..f913e9bd57ed 100644
> --- a/drivers/soc/qcom/pmic_glink.c
> +++ b/drivers/soc/qcom/pmic_glink.c
> @@ -265,10 +265,17 @@ static int pmic_glink_probe(struct platform_device *pdev)
>  
>  	pg->client_mask = *match_data;
>  
> +	pg->pdr = pdr_handle_alloc(pmic_glink_pdr_callback, pg);
> +	if (IS_ERR(pg->pdr)) {
> +		ret = dev_err_probe(&pdev->dev, PTR_ERR(pg->pdr),
> +				    "failed to initialize pdr\n");
> +		return ret;
> +	}
> +
>  	if (pg->client_mask & BIT(PMIC_GLINK_CLIENT_UCSI)) {
>  		ret = pmic_glink_add_aux_device(pg, &pg->ucsi_aux, "ucsi");
>  		if (ret)
> -			return ret;
> +			goto out_release_pdr_handle;
>  	}
>  	if (pg->client_mask & BIT(PMIC_GLINK_CLIENT_ALTMODE)) {
>  		ret = pmic_glink_add_aux_device(pg, &pg->altmode_aux, "altmode");
> @@ -281,17 +288,11 @@ static int pmic_glink_probe(struct platform_device *pdev)
>  			goto out_release_altmode_aux;
>  	}
>  
> -	pg->pdr = pdr_handle_alloc(pmic_glink_pdr_callback, pg);
> -	if (IS_ERR(pg->pdr)) {
> -		ret = dev_err_probe(&pdev->dev, PTR_ERR(pg->pdr), "failed to initialize pdr\n");
> -		goto out_release_aux_devices;
> -	}
> -
>  	service = pdr_add_lookup(pg->pdr, "tms/servreg", "msm/adsp/charger_pd");
>  	if (IS_ERR(service)) {
>  		ret = dev_err_probe(&pdev->dev, PTR_ERR(service),
>  				    "failed adding pdr lookup for charger_pd\n");
> -		goto out_release_pdr_handle;
> +		goto out_release_aux_devices;
>  	}
>  
>  	mutex_lock(&__pmic_glink_lock);
> @@ -300,8 +301,6 @@ static int pmic_glink_probe(struct platform_device *pdev)
>  
>  	return 0;
>  
> -out_release_pdr_handle:
> -	pdr_handle_release(pg->pdr);
>  out_release_aux_devices:
>  	if (pg->client_mask & BIT(PMIC_GLINK_CLIENT_BATT))
>  		pmic_glink_del_aux_device(pg, &pg->ps_aux);
> @@ -311,6 +310,8 @@ static int pmic_glink_probe(struct platform_device *pdev)
>  out_release_ucsi_aux:
>  	if (pg->client_mask & BIT(PMIC_GLINK_CLIENT_UCSI))
>  		pmic_glink_del_aux_device(pg, &pg->ucsi_aux);
> +out_release_pdr_handle:
> +	pdr_handle_release(pg->pdr);
>  
>  	return ret;
>  }
> -- 
> 2.43.0
> 

Re: [PATCH 4/6] soc: qcom: pmic_glink: Fix boot when QRTR=m

[Dmitry Baryshkov]

On Sat, 17 Feb 2024 at 17:03, Johan Hovold <johan+linaro@kernel.org> wrote:
>
> From: Rob Clark <robdclark@chromium.org>
>
> We need to bail out before adding/removing devices if we are going to
> -EPROBE_DEFER. Otherwise boot can get stuck in a probe deferral loop due
> to a long-standing issue in driver core (see fbc35b45f9f6 ("Add
> documentation on meaning of -EPROBE_DEFER")).
>
> Deregistering the altmode child device can potentially also trigger bugs
> in the DRM bridge implementation, which does not expect bridges to go
> away.
>
> Suggested-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> Signed-off-by: Rob Clark <robdclark@chromium.org>
> Link: https://lore.kernel.org/r/20231213210644.8702-1-robdclark@gmail.com
> [ johan: rebase on 6.8-rc4, amend commit message and mention DRM ]
> Fixes: 58ef4ece1e41 ("soc: qcom: pmic_glink: Introduce base PMIC GLINK driver")
> Cc: stable@vger.kernel.org      # 6.3
> Cc: Bjorn Andersson <andersson@kernel.org>
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
> ---
>  drivers/soc/qcom/pmic_glink.c | 21 +++++++++++----------
>  1 file changed, 11 insertions(+), 10 deletions(-)
>

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

-- 
With best wishes
Dmitry

Re: [PATCH 4/6] soc: qcom: pmic_glink: Fix boot when QRTR=m

[Neil Armstrong]

On 17/02/2024 16:02, Johan Hovold wrote:
> From: Rob Clark <robdclark@chromium.org>
> 
> We need to bail out before adding/removing devices if we are going to
> -EPROBE_DEFER. Otherwise boot can get stuck in a probe deferral loop due
> to a long-standing issue in driver core (see fbc35b45f9f6 ("Add
> documentation on meaning of -EPROBE_DEFER")).
> 
> Deregistering the altmode child device can potentially also trigger bugs
> in the DRM bridge implementation, which does not expect bridges to go
> away.
> 
> Suggested-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> Signed-off-by: Rob Clark <robdclark@chromium.org>
> Link: https://lore.kernel.org/r/20231213210644.8702-1-robdclark@gmail.com
> [ johan: rebase on 6.8-rc4, amend commit message and mention DRM ]
> Fixes: 58ef4ece1e41 ("soc: qcom: pmic_glink: Introduce base PMIC GLINK driver")
> Cc: stable@vger.kernel.org      # 6.3
> Cc: Bjorn Andersson <andersson@kernel.org>
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
> ---
>   drivers/soc/qcom/pmic_glink.c | 21 +++++++++++----------
>   1 file changed, 11 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/soc/qcom/pmic_glink.c b/drivers/soc/qcom/pmic_glink.c
> index f4bfd24386f1..f913e9bd57ed 100644
> --- a/drivers/soc/qcom/pmic_glink.c
> +++ b/drivers/soc/qcom/pmic_glink.c
> @@ -265,10 +265,17 @@ static int pmic_glink_probe(struct platform_device *pdev)
>   
>   	pg->client_mask = *match_data;
>   
> +	pg->pdr = pdr_handle_alloc(pmic_glink_pdr_callback, pg);
> +	if (IS_ERR(pg->pdr)) {
> +		ret = dev_err_probe(&pdev->dev, PTR_ERR(pg->pdr),
> +				    "failed to initialize pdr\n");
> +		return ret;
> +	}
> +
>   	if (pg->client_mask & BIT(PMIC_GLINK_CLIENT_UCSI)) {
>   		ret = pmic_glink_add_aux_device(pg, &pg->ucsi_aux, "ucsi");
>   		if (ret)
> -			return ret;
> +			goto out_release_pdr_handle;
>   	}
>   	if (pg->client_mask & BIT(PMIC_GLINK_CLIENT_ALTMODE)) {
>   		ret = pmic_glink_add_aux_device(pg, &pg->altmode_aux, "altmode");
> @@ -281,17 +288,11 @@ static int pmic_glink_probe(struct platform_device *pdev)
>   			goto out_release_altmode_aux;
>   	}
>   
> -	pg->pdr = pdr_handle_alloc(pmic_glink_pdr_callback, pg);
> -	if (IS_ERR(pg->pdr)) {
> -		ret = dev_err_probe(&pdev->dev, PTR_ERR(pg->pdr), "failed to initialize pdr\n");
> -		goto out_release_aux_devices;
> -	}
> -
>   	service = pdr_add_lookup(pg->pdr, "tms/servreg", "msm/adsp/charger_pd");
>   	if (IS_ERR(service)) {
>   		ret = dev_err_probe(&pdev->dev, PTR_ERR(service),
>   				    "failed adding pdr lookup for charger_pd\n");
> -		goto out_release_pdr_handle;
> +		goto out_release_aux_devices;
>   	}
>   
>   	mutex_lock(&__pmic_glink_lock);
> @@ -300,8 +301,6 @@ static int pmic_glink_probe(struct platform_device *pdev)
>   
>   	return 0;
>   
> -out_release_pdr_handle:
> -	pdr_handle_release(pg->pdr);
>   out_release_aux_devices:
>   	if (pg->client_mask & BIT(PMIC_GLINK_CLIENT_BATT))
>   		pmic_glink_del_aux_device(pg, &pg->ps_aux);
> @@ -311,6 +310,8 @@ static int pmic_glink_probe(struct platform_device *pdev)
>   out_release_ucsi_aux:
>   	if (pg->client_mask & BIT(PMIC_GLINK_CLIENT_UCSI))
>   		pmic_glink_del_aux_device(pg, &pg->ucsi_aux);
> +out_release_pdr_handle:
> +	pdr_handle_release(pg->pdr);
>   
>   	return ret;
>   }

Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>

[PATCH 5/6] phy: qcom-qmp-combo: fix drm bridge registration

[Johan Hovold]

Due to a long-standing issue in driver core, drivers may not probe defer
after having registered child devices to avoid triggering a probe
deferral loop (see fbc35b45f9f6 ("Add documentation on meaning of
-EPROBE_DEFER")).

This could potentially also trigger a bug in the DRM bridge
implementation which does not expect bridges to go away even if device
links may avoid triggering this (when enabled).

Move registration of the DRM aux bridge to after looking up clocks and
other resources.

Note that PHY creation can in theory also trigger a probe deferral when
a 'phy' supply is used. This does not seem to affect the QMP PHY driver
but the PHY subsystem should be reworked to address this (i.e. by
separating initialisation and registration of the PHY).

Fixes: 35921910bbd0 ("phy: qcom: qmp-combo: switch to DRM_AUX_BRIDGE")
Fixes: 1904c3f578dc ("phy: qcom-qmp-combo: Introduce drm_bridge")
Cc: stable@vger.kernel.org      # 6.5
Cc: Bjorn Andersson <quic_bjorande@quicinc.com>
Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
---
 drivers/phy/qualcomm/phy-qcom-qmp-combo.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-combo.c b/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
index 1ad10110dd25..e19d6a084f10 100644
--- a/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
+++ b/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
@@ -3566,10 +3566,6 @@ static int qmp_combo_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
-	ret = drm_aux_bridge_register(dev);
-	if (ret)
-		return ret;
-
 	/* Check for legacy binding with child nodes. */
 	usb_np = of_get_child_by_name(dev->of_node, "usb3-phy");
 	if (usb_np) {
@@ -3589,6 +3585,10 @@ static int qmp_combo_probe(struct platform_device *pdev)
 	if (ret)
 		goto err_node_put;
 
+	ret = drm_aux_bridge_register(dev);
+	if (ret)
+		goto err_node_put;
+
 	pm_runtime_set_active(dev);
 	ret = devm_pm_runtime_enable(dev);
 	if (ret)
-- 
2.43.0

Re: [PATCH 5/6] phy: qcom-qmp-combo: fix drm bridge registration

[Neil Armstrong]

On 17/02/2024 16:02, Johan Hovold wrote:
> Due to a long-standing issue in driver core, drivers may not probe defer
> after having registered child devices to avoid triggering a probe
> deferral loop (see fbc35b45f9f6 ("Add documentation on meaning of
> -EPROBE_DEFER")).
> 
> This could potentially also trigger a bug in the DRM bridge
> implementation which does not expect bridges to go away even if device
> links may avoid triggering this (when enabled).
> 
> Move registration of the DRM aux bridge to after looking up clocks and
> other resources.
> 
> Note that PHY creation can in theory also trigger a probe deferral when
> a 'phy' supply is used. This does not seem to affect the QMP PHY driver
> but the PHY subsystem should be reworked to address this (i.e. by
> separating initialisation and registration of the PHY).
> 
> Fixes: 35921910bbd0 ("phy: qcom: qmp-combo: switch to DRM_AUX_BRIDGE")
> Fixes: 1904c3f578dc ("phy: qcom-qmp-combo: Introduce drm_bridge")
> Cc: stable@vger.kernel.org      # 6.5
> Cc: Bjorn Andersson <quic_bjorande@quicinc.com>
> Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
> ---
>   drivers/phy/qualcomm/phy-qcom-qmp-combo.c | 8 ++++----
>   1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-combo.c b/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
> index 1ad10110dd25..e19d6a084f10 100644
> --- a/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
> +++ b/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
> @@ -3566,10 +3566,6 @@ static int qmp_combo_probe(struct platform_device *pdev)
>   	if (ret)
>   		return ret;
>   
> -	ret = drm_aux_bridge_register(dev);
> -	if (ret)
> -		return ret;
> -
>   	/* Check for legacy binding with child nodes. */
>   	usb_np = of_get_child_by_name(dev->of_node, "usb3-phy");
>   	if (usb_np) {
> @@ -3589,6 +3585,10 @@ static int qmp_combo_probe(struct platform_device *pdev)
>   	if (ret)
>   		goto err_node_put;
>   
> +	ret = drm_aux_bridge_register(dev);
> +	if (ret)
> +		goto err_node_put;
> +
>   	pm_runtime_set_active(dev);
>   	ret = devm_pm_runtime_enable(dev);
>   	if (ret)

Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>

Re: [PATCH 5/6] phy: qcom-qmp-combo: fix drm bridge registration

[Bjorn Andersson]

On Sat, Feb 17, 2024 at 04:02:27PM +0100, Johan Hovold wrote:
> Due to a long-standing issue in driver core, drivers may not probe defer
> after having registered child devices to avoid triggering a probe
> deferral loop (see fbc35b45f9f6 ("Add documentation on meaning of
> -EPROBE_DEFER")).
> 
> This could potentially also trigger a bug in the DRM bridge
> implementation which does not expect bridges to go away even if device
> links may avoid triggering this (when enabled).
> 
> Move registration of the DRM aux bridge to after looking up clocks and
> other resources.
> 
> Note that PHY creation can in theory also trigger a probe deferral when
> a 'phy' supply is used. This does not seem to affect the QMP PHY driver
> but the PHY subsystem should be reworked to address this (i.e. by
> separating initialisation and registration of the PHY).
> 
> Fixes: 35921910bbd0 ("phy: qcom: qmp-combo: switch to DRM_AUX_BRIDGE")
> Fixes: 1904c3f578dc ("phy: qcom-qmp-combo: Introduce drm_bridge")
> Cc: stable@vger.kernel.org      # 6.5
> Cc: Bjorn Andersson <quic_bjorande@quicinc.com>
> Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>

Reviewed-by: Bjorn Andersson <andersson@kernel.org>

Regards,
Bjorn

> ---
>  drivers/phy/qualcomm/phy-qcom-qmp-combo.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-combo.c b/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
> index 1ad10110dd25..e19d6a084f10 100644
> --- a/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
> +++ b/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
> @@ -3566,10 +3566,6 @@ static int qmp_combo_probe(struct platform_device *pdev)
>  	if (ret)
>  		return ret;
>  
> -	ret = drm_aux_bridge_register(dev);
> -	if (ret)
> -		return ret;
> -
>  	/* Check for legacy binding with child nodes. */
>  	usb_np = of_get_child_by_name(dev->of_node, "usb3-phy");
>  	if (usb_np) {
> @@ -3589,6 +3585,10 @@ static int qmp_combo_probe(struct platform_device *pdev)
>  	if (ret)
>  		goto err_node_put;
>  
> +	ret = drm_aux_bridge_register(dev);
> +	if (ret)
> +		goto err_node_put;
> +
>  	pm_runtime_set_active(dev);
>  	ret = devm_pm_runtime_enable(dev);
>  	if (ret)
> -- 
> 2.43.0
> 

Re: [PATCH 5/6] phy: qcom-qmp-combo: fix drm bridge registration

[Dmitry Baryshkov]

On Sat, 17 Feb 2024 at 17:03, Johan Hovold <johan+linaro@kernel.org> wrote:
>
> Due to a long-standing issue in driver core, drivers may not probe defer
> after having registered child devices to avoid triggering a probe
> deferral loop (see fbc35b45f9f6 ("Add documentation on meaning of
> -EPROBE_DEFER")).
>
> This could potentially also trigger a bug in the DRM bridge
> implementation which does not expect bridges to go away even if device
> links may avoid triggering this (when enabled).
>
> Move registration of the DRM aux bridge to after looking up clocks and
> other resources.
>
> Note that PHY creation can in theory also trigger a probe deferral when
> a 'phy' supply is used. This does not seem to affect the QMP PHY driver
> but the PHY subsystem should be reworked to address this (i.e. by
> separating initialisation and registration of the PHY).
>
> Fixes: 35921910bbd0 ("phy: qcom: qmp-combo: switch to DRM_AUX_BRIDGE")
> Fixes: 1904c3f578dc ("phy: qcom-qmp-combo: Introduce drm_bridge")
> Cc: stable@vger.kernel.org      # 6.5
> Cc: Bjorn Andersson <quic_bjorande@quicinc.com>
> Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
> ---
>  drivers/phy/qualcomm/phy-qcom-qmp-combo.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>


-- 
With best wishes
Dmitry

Re: [PATCH 5/6] phy: qcom-qmp-combo: fix drm bridge registration

[Vinod Koul]

On 17-02-24, 16:02, Johan Hovold wrote:
> Due to a long-standing issue in driver core, drivers may not probe defer
> after having registered child devices to avoid triggering a probe
> deferral loop (see fbc35b45f9f6 ("Add documentation on meaning of
> -EPROBE_DEFER")).
> 
> This could potentially also trigger a bug in the DRM bridge
> implementation which does not expect bridges to go away even if device
> links may avoid triggering this (when enabled).
> 
> Move registration of the DRM aux bridge to after looking up clocks and
> other resources.
> 
> Note that PHY creation can in theory also trigger a probe deferral when
> a 'phy' supply is used. This does not seem to affect the QMP PHY driver
> but the PHY subsystem should be reworked to address this (i.e. by
> separating initialisation and registration of the PHY).

Acked-by: Vinod Koul <vkoul@kernel.org>

-- 
~Vinod

[PATCH 6/6] phy: qcom-qmp-combo: fix type-c switch registration

[Johan Hovold]

Due to a long-standing issue in driver core, drivers may not probe defer
after having registered child devices to avoid triggering a probe
deferral loop (see fbc35b45f9f6 ("Add documentation on meaning of
-EPROBE_DEFER")).

Move registration of the typec switch to after looking up clocks and
other resources.

Note that PHY creation can in theory also trigger a probe deferral when
a 'phy' supply is used. This does not seem to affect the QMP PHY driver
but the PHY subsystem should be reworked to address this (i.e. by
separating initialisation and registration of the PHY).

Fixes: 2851117f8f42 ("phy: qcom-qmp-combo: Introduce orientation switching")
Cc: stable@vger.kernel.org      # 6.5
Cc: Bjorn Andersson <quic_bjorande@quicinc.com>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
---
 drivers/phy/qualcomm/phy-qcom-qmp-combo.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-combo.c b/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
index e19d6a084f10..17c4ad7553a5 100644
--- a/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
+++ b/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
@@ -3562,10 +3562,6 @@ static int qmp_combo_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
-	ret = qmp_combo_typec_switch_register(qmp);
-	if (ret)
-		return ret;
-
 	/* Check for legacy binding with child nodes. */
 	usb_np = of_get_child_by_name(dev->of_node, "usb3-phy");
 	if (usb_np) {
@@ -3585,6 +3581,10 @@ static int qmp_combo_probe(struct platform_device *pdev)
 	if (ret)
 		goto err_node_put;
 
+	ret = qmp_combo_typec_switch_register(qmp);
+	if (ret)
+		goto err_node_put;
+
 	ret = drm_aux_bridge_register(dev);
 	if (ret)
 		goto err_node_put;
-- 
2.43.0

Re: [PATCH 6/6] phy: qcom-qmp-combo: fix type-c switch registration

[Bjorn Andersson]

On Sat, Feb 17, 2024 at 04:02:28PM +0100, Johan Hovold wrote:
> Due to a long-standing issue in driver core, drivers may not probe defer
> after having registered child devices to avoid triggering a probe
> deferral loop (see fbc35b45f9f6 ("Add documentation on meaning of
> -EPROBE_DEFER")).
> 
> Move registration of the typec switch to after looking up clocks and
> other resources.
> 
> Note that PHY creation can in theory also trigger a probe deferral when
> a 'phy' supply is used. This does not seem to affect the QMP PHY driver
> but the PHY subsystem should be reworked to address this (i.e. by
> separating initialisation and registration of the PHY).
> 
> Fixes: 2851117f8f42 ("phy: qcom-qmp-combo: Introduce orientation switching")
> Cc: stable@vger.kernel.org      # 6.5
> Cc: Bjorn Andersson <quic_bjorande@quicinc.com>
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>

Reviewed-by: Bjorn Andersson <andersson@kernel.org>

Regards,
Bjorn

> ---
>  drivers/phy/qualcomm/phy-qcom-qmp-combo.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-combo.c b/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
> index e19d6a084f10..17c4ad7553a5 100644
> --- a/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
> +++ b/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
> @@ -3562,10 +3562,6 @@ static int qmp_combo_probe(struct platform_device *pdev)
>  	if (ret)
>  		return ret;
>  
> -	ret = qmp_combo_typec_switch_register(qmp);
> -	if (ret)
> -		return ret;
> -
>  	/* Check for legacy binding with child nodes. */
>  	usb_np = of_get_child_by_name(dev->of_node, "usb3-phy");
>  	if (usb_np) {
> @@ -3585,6 +3581,10 @@ static int qmp_combo_probe(struct platform_device *pdev)
>  	if (ret)
>  		goto err_node_put;
>  
> +	ret = qmp_combo_typec_switch_register(qmp);
> +	if (ret)
> +		goto err_node_put;
> +
>  	ret = drm_aux_bridge_register(dev);
>  	if (ret)
>  		goto err_node_put;
> -- 
> 2.43.0
> 

Re: [PATCH 6/6] phy: qcom-qmp-combo: fix type-c switch registration

[Dmitry Baryshkov]

On Sat, 17 Feb 2024 at 17:03, Johan Hovold <johan+linaro@kernel.org> wrote:
>
> Due to a long-standing issue in driver core, drivers may not probe defer
> after having registered child devices to avoid triggering a probe
> deferral loop (see fbc35b45f9f6 ("Add documentation on meaning of
> -EPROBE_DEFER")).
>
> Move registration of the typec switch to after looking up clocks and
> other resources.
>
> Note that PHY creation can in theory also trigger a probe deferral when
> a 'phy' supply is used. This does not seem to affect the QMP PHY driver
> but the PHY subsystem should be reworked to address this (i.e. by
> separating initialisation and registration of the PHY).
>
> Fixes: 2851117f8f42 ("phy: qcom-qmp-combo: Introduce orientation switching")
> Cc: stable@vger.kernel.org      # 6.5
> Cc: Bjorn Andersson <quic_bjorande@quicinc.com>
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
> ---
>  drivers/phy/qualcomm/phy-qcom-qmp-combo.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

Note to myself (or to anybody else, who has spare hands), we should
probably implement the same changes for phy-qcom-qmp-usbc.c

>
> diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-combo.c b/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
> index e19d6a084f10..17c4ad7553a5 100644
> --- a/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
> +++ b/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
> @@ -3562,10 +3562,6 @@ static int qmp_combo_probe(struct platform_device *pdev)
>         if (ret)
>                 return ret;
>
> -       ret = qmp_combo_typec_switch_register(qmp);
> -       if (ret)
> -               return ret;
> -
>         /* Check for legacy binding with child nodes. */
>         usb_np = of_get_child_by_name(dev->of_node, "usb3-phy");
>         if (usb_np) {
> @@ -3585,6 +3581,10 @@ static int qmp_combo_probe(struct platform_device *pdev)
>         if (ret)
>                 goto err_node_put;
>
> +       ret = qmp_combo_typec_switch_register(qmp);
> +       if (ret)
> +               goto err_node_put;
> +
>         ret = drm_aux_bridge_register(dev);
>         if (ret)
>                 goto err_node_put;
> --
> 2.43.0
>


-- 
With best wishes
Dmitry

Re: [PATCH 6/6] phy: qcom-qmp-combo: fix type-c switch registration

[Vinod Koul]

On 17-02-24, 16:02, Johan Hovold wrote:
> Due to a long-standing issue in driver core, drivers may not probe defer
> after having registered child devices to avoid triggering a probe
> deferral loop (see fbc35b45f9f6 ("Add documentation on meaning of
> -EPROBE_DEFER")).
> 
> Move registration of the typec switch to after looking up clocks and
> other resources.
> 
> Note that PHY creation can in theory also trigger a probe deferral when
> a 'phy' supply is used. This does not seem to affect the QMP PHY driver
> but the PHY subsystem should be reworked to address this (i.e. by
> separating initialisation and registration of the PHY).

Acked-by: Vinod Koul <vkoul@kernel.org>

-- 
~Vinod