usb: common: usb-conn-gpio: Prevent bailing out if initial role is none

usb: common: usb-conn-gpio: Prevent bailing out if initial role is none

[Prashanth K]

Currently if we bootup a device without cable connected, then
usb-conn-gpio won't call set_role() since last_role is same as
current role. This happens because during probe last_role gets
initialised to zero.

To avoid this, add a new flag initial_det in usb_conn_info,
which is used to prevent bailing out during init detection.

Fixes: 4602f3bff266 ("usb: common: add USB GPIO based connection detection driver")
Signed-off-by: Prashanth K <quic_prashk@quicinc.com>
---
 drivers/usb/common/usb-conn-gpio.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/common/usb-conn-gpio.c b/drivers/usb/common/usb-conn-gpio.c
index 766005d..46290ff 100644
--- a/drivers/usb/common/usb-conn-gpio.c
+++ b/drivers/usb/common/usb-conn-gpio.c
@@ -42,6 +42,7 @@ struct usb_conn_info {
 
 	struct power_supply_desc desc;
 	struct power_supply *charger;
+	bool initial_det;
 };
 
 /*
@@ -86,11 +87,13 @@ static void usb_conn_detect_cable(struct work_struct *work)
 	dev_dbg(info->dev, "role %s -> %s, gpios: id %d, vbus %d\n",
 		usb_role_string(info->last_role), usb_role_string(role), id, vbus);
 
-	if (info->last_role == role) {
+	if (!info->initial_det && info->last_role == role) {
 		dev_warn(info->dev, "repeated role: %s\n", usb_role_string(role));
 		return;
 	}
 
+	info->initial_det = false;
+
 	if (info->last_role == USB_ROLE_HOST && info->vbus)
 		regulator_disable(info->vbus);
 
@@ -258,6 +261,7 @@ static int usb_conn_probe(struct platform_device *pdev)
 	device_set_wakeup_capable(&pdev->dev, true);
 
 	/* Perform initial detection */
+	info->initial_det = true;
 	usb_conn_queue_dwork(info, 0);
 
 	return 0;
-- 
2.7.4

Re: usb: common: usb-conn-gpio: Prevent bailing out if initial role is none

[Greg Kroah-Hartman]

On Thu, Jul 06, 2023 at 03:40:58PM +0530, Prashanth K wrote:
> Currently if we bootup a device without cable connected, then
> usb-conn-gpio won't call set_role() since last_role is same as
> current role. This happens because during probe last_role gets
> initialised to zero.
> 
> To avoid this, add a new flag initial_det in usb_conn_info,
> which is used to prevent bailing out during init detection.
> 
> Fixes: 4602f3bff266 ("usb: common: add USB GPIO based connection detection driver")
> Signed-off-by: Prashanth K <quic_prashk@quicinc.com>
> ---
>  drivers/usb/common/usb-conn-gpio.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/common/usb-conn-gpio.c b/drivers/usb/common/usb-conn-gpio.c
> index 766005d..46290ff 100644
> --- a/drivers/usb/common/usb-conn-gpio.c
> +++ b/drivers/usb/common/usb-conn-gpio.c
> @@ -42,6 +42,7 @@ struct usb_conn_info {
>  
>  	struct power_supply_desc desc;
>  	struct power_supply *charger;
> +	bool initial_det;

What does "initial_det" mean?  Please document this better.

>  };
>  
>  /*
> @@ -86,11 +87,13 @@ static void usb_conn_detect_cable(struct work_struct *work)
>  	dev_dbg(info->dev, "role %s -> %s, gpios: id %d, vbus %d\n",
>  		usb_role_string(info->last_role), usb_role_string(role), id, vbus);
>  
> -	if (info->last_role == role) {
> +	if (!info->initial_det && info->last_role == role) {
>  		dev_warn(info->dev, "repeated role: %s\n", usb_role_string(role));
>  		return;
>  	}
>  
> +	info->initial_det = false;
> +
>  	if (info->last_role == USB_ROLE_HOST && info->vbus)
>  		regulator_disable(info->vbus);
>  
> @@ -258,6 +261,7 @@ static int usb_conn_probe(struct platform_device *pdev)
>  	device_set_wakeup_capable(&pdev->dev, true);
>  
>  	/* Perform initial detection */
> +	info->initial_det = true;

What is protecting this from changing right after you test for it?

thanks,

greg k-h

Re: usb: common: usb-conn-gpio: Prevent bailing out if initial role is none

[Prashanth K]

On 25-07-23 09:04 pm, Greg Kroah-Hartman wrote:
> On Thu, Jul 06, 2023 at 03:40:58PM +0530, Prashanth K wrote:
>> Currently if we bootup a device without cable connected, then
>> usb-conn-gpio won't call set_role() since last_role is same as
>> current role. This happens because during probe last_role gets
>> initialised to zero.
>>
>> To avoid this, add a new flag initial_det in usb_conn_info,
>> which is used to prevent bailing out during init detection.
>>
>> Fixes: 4602f3bff266 ("usb: common: add USB GPIO based connection detection driver")
>> Signed-off-by: Prashanth K <quic_prashk@quicinc.com>
>> ---
>>   drivers/usb/common/usb-conn-gpio.c | 6 +++++-
>>   1 file changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/usb/common/usb-conn-gpio.c b/drivers/usb/common/usb-conn-gpio.c
>> index 766005d..46290ff 100644
>> --- a/drivers/usb/common/usb-conn-gpio.c
>> +++ b/drivers/usb/common/usb-conn-gpio.c
>> @@ -42,6 +42,7 @@ struct usb_conn_info {
>>   
>>   	struct power_supply_desc desc;
>>   	struct power_supply *charger;
>> +	bool initial_det;
> 
> What does "initial_det" mean?  Please document this better.
> 
Yea sure, will update that. It was supposed to mean initial_detection.
>>   };
>>   
>>   /*
>> @@ -86,11 +87,13 @@ static void usb_conn_detect_cable(struct work_struct *work)
>>   	dev_dbg(info->dev, "role %s -> %s, gpios: id %d, vbus %d\n",
>>   		usb_role_string(info->last_role), usb_role_string(role), id, vbus);
>>   
>> -	if (info->last_role == role) {
>> +	if (!info->initial_det && info->last_role == role) {
>>   		dev_warn(info->dev, "repeated role: %s\n", usb_role_string(role));
>>   		return;
>>   	}
>>   
>> +	info->initial_det = false;
>> +
>>   	if (info->last_role == USB_ROLE_HOST && info->vbus)
>>   		regulator_disable(info->vbus);
>>   
>> @@ -258,6 +261,7 @@ static int usb_conn_probe(struct platform_device *pdev)
>>   	device_set_wakeup_capable(&pdev->dev, true);
>>   
>>   	/* Perform initial detection */
>> +	info->initial_det = true;
> 
> What is protecting this from changing right after you test for it?
> 
> thanks,
> 
> greg k-h

Hi Greg, this variable is only used/changed by usb_conn_detect_cable() 
which is called in next line. So the chance of it changing is none.
Basically this initial_det flag points if its initial detection or not.
If yes, then prevent bailing out in usb_conn_detect_cable(). Please let 
me know if your comment was regarding something else.

Regards,
Prashanth K