usb: dwc3: Prioritize extcon over USB role switching API

It is necessary that:

   ROLE_SWITCH && device_property_read_bool(dwc->dev, "usb-role-switch")

is true in order for dwc3_get_dr_mode() to _not_ force us from OTG to
PERIPHERAL mode here:

   if (mode == USB_DR_MODE_OTG &&
       (!IS_ENABLED(CONFIG_USB_ROLE_SWITCH) ||
        !device_property_read_bool(dwc->dev, "usb-role-switch")) &&
	!DWC3_VER_IS_PRIOR(DWC3, 330A))
	mode = USB_DR_MODE_PERIPHERAL;

and dwc3_drd_init() to be called later in dwc3_core_init_mode(). So,
to avoid always ignoring extcon device returned by dwc3_get_extcon()
change dwc3_drd_init() to check and use it first, before checking if
dwc3_setup_role_switch() should be called.

Cc: Felipe Balbi <balbi@kernel.org>
Cc: Thinh Nguyen <thinhn@synopsys.com>
Cc: linux-usb@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
---

Hopefully I didn't miss something important making this patch
unnecessary. Don't know if this is a good solution or not, part of me
thinks than maybe changing the aforementioned code in
dwc3_get_dr_mode() to account for extcon wopuld be
simpler/better. Happy to rework this.

 drivers/usb/dwc3/drd.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

--
2.25.1

Andrey Smirnov wrote:
> It is necessary that:
> 
>    ROLE_SWITCH && device_property_read_bool(dwc->dev, "usb-role-switch")
> 
> is true in order for dwc3_get_dr_mode() to _not_ force us from OTG to
> PERIPHERAL mode here:
> 
>    if (mode == USB_DR_MODE_OTG &&
>        (!IS_ENABLED(CONFIG_USB_ROLE_SWITCH) ||
>         !device_property_read_bool(dwc->dev, "usb-role-switch")) &&
> 	!DWC3_VER_IS_PRIOR(DWC3, 330A))
> 	mode = USB_DR_MODE_PERIPHERAL;
> 
> and dwc3_drd_init() to be called later in dwc3_core_init_mode(). So,
> to avoid always ignoring extcon device returned by dwc3_get_extcon()
> change dwc3_drd_init() to check and use it first, before checking if
> dwc3_setup_role_switch() should be called.
> 
> Cc: Felipe Balbi <balbi@kernel.org>
> Cc: Thinh Nguyen <thinhn@synopsys.com>
> Cc: linux-usb@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
> ---
> 
> Hopefully I didn't miss something important making this patch
> unnecessary. Don't know if this is a good solution or not, part of me
> thinks than maybe changing the aforementioned code in
> dwc3_get_dr_mode() to account for extcon wopuld be
> simpler/better. Happy to rework this.

The driver either use extcon or usb-role-switch. It doesn't make sense to
enable usb-role-switch for extcon just so the driver doesn't default
the dr_mode to peripheral.

Perhaps, this is what you're looking for? (code is not tested)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index bffd719b8b52..a52331ea7a0d 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -86,7 +86,7 @@ static int dwc3_get_dr_mode(struct dwc3 *dwc)
                 * mode. If the controller supports DRD but the dr_mode is not
                 * specified or set to OTG, then set the mode to peripheral.
                 */
-               if (mode == USB_DR_MODE_OTG &&
+               if (mode == USB_DR_MODE_OTG && !dwc->edev &&
                    (!IS_ENABLED(CONFIG_USB_ROLE_SWITCH) ||
                     !device_property_read_bool(dwc->dev, "usb-role-switch")) &&
                    !DWC3_VER_IS_PRIOR(DWC3, 330A))
@@ -1715,6 +1715,13 @@ static int dwc3_probe(struct platform_device *pdev)
                goto err2;
        }
 
+       dwc->edev = dwc3_get_extcon(dwc);
+       if (IS_ERR(dwc->edev)) {
+               ret = PTR_ERR(dwc->edev);
+               dev_err(dwc->dev, "failed to get extcon %d\n", ret);
+               goto err3;
+       }
+
        ret = dwc3_get_dr_mode(dwc);
        if (ret)
                goto err3;
diff --git a/drivers/usb/dwc3/drd.c b/drivers/usb/dwc3/drd.c
index 63089c7fb530..d02fcfdc74db 100644
--- a/drivers/usb/dwc3/drd.c
+++ b/drivers/usb/dwc3/drd.c
@@ -585,16 +585,7 @@ int dwc3_drd_init(struct dwc3 *dwc)
 {
        int ret, irq;
 
-       dwc->edev = dwc3_get_extcon(dwc);
-       if (IS_ERR(dwc->edev))
-               return PTR_ERR(dwc->edev);
-
-       if (ROLE_SWITCH &&
-           device_property_read_bool(dwc->dev, "usb-role-switch")) {
-               ret = dwc3_setup_role_switch(dwc);
-               if (ret < 0)
-                       return ret;
-       } else if (dwc->edev) {
+       if (dwc->edev) {
                dwc->edev_nb.notifier_call = dwc3_drd_notifier;
                ret = extcon_register_notifier(dwc->edev, EXTCON_USB_HOST,
                                               &dwc->edev_nb);
@@ -604,6 +595,11 @@ int dwc3_drd_init(struct dwc3 *dwc)
                }
 
                dwc3_drd_update(dwc);
+       } else if (ROLE_SWITCH &&
+                  device_property_read_bool(dwc->dev, "usb-role-switch")) {
+               ret = dwc3_setup_role_switch(dwc);
+               if (ret < 0)
+                       return ret;
        } else {
                dwc3_set_prtcap(dwc, DWC3_GCTL_PRTCAP_OTG);

On Wed, Feb 2, 2022 at 6:54 PM Thinh Nguyen <Thinh.Nguyen@synopsys.com> wrote:
>
> Andrey Smirnov wrote:
> > It is necessary that:
> >
> >    ROLE_SWITCH && device_property_read_bool(dwc->dev, "usb-role-switch")
> >
> > is true in order for dwc3_get_dr_mode() to _not_ force us from OTG to
> > PERIPHERAL mode here:
> >
> >    if (mode == USB_DR_MODE_OTG &&
> >        (!IS_ENABLED(CONFIG_USB_ROLE_SWITCH) ||
> >         !device_property_read_bool(dwc->dev, "usb-role-switch")) &&
> >       !DWC3_VER_IS_PRIOR(DWC3, 330A))
> >       mode = USB_DR_MODE_PERIPHERAL;
> >
> > and dwc3_drd_init() to be called later in dwc3_core_init_mode(). So,
> > to avoid always ignoring extcon device returned by dwc3_get_extcon()
> > change dwc3_drd_init() to check and use it first, before checking if
> > dwc3_setup_role_switch() should be called.
> >
> > Cc: Felipe Balbi <balbi@kernel.org>
> > Cc: Thinh Nguyen <thinhn@synopsys.com>
> > Cc: linux-usb@vger.kernel.org
> > Cc: linux-kernel@vger.kernel.org
> > Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
> > ---
> >
> > Hopefully I didn't miss something important making this patch
> > unnecessary. Don't know if this is a good solution or not, part of me
> > thinks than maybe changing the aforementioned code in
> > dwc3_get_dr_mode() to account for extcon wopuld be
> > simpler/better. Happy to rework this.
>
> The driver either use extcon or usb-role-switch. It doesn't make sense to
> enable usb-role-switch for extcon just so the driver doesn't default
> the dr_mode to peripheral.
>
> Perhaps, this is what you're looking for? (code is not tested)
>

Yeah that kind of what I meant by "maybe changing the aforementioned code in
dwc3_get_dr_mode() to account for extcon wopuld be
simpler/better." OK let me rework the patch to do that.

> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index bffd719b8b52..a52331ea7a0d 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -86,7 +86,7 @@ static int dwc3_get_dr_mode(struct dwc3 *dwc)
>                  * mode. If the controller supports DRD but the dr_mode is not
>                  * specified or set to OTG, then set the mode to peripheral.
>                  */
> -               if (mode == USB_DR_MODE_OTG &&
> +               if (mode == USB_DR_MODE_OTG && !dwc->edev &&
>                     (!IS_ENABLED(CONFIG_USB_ROLE_SWITCH) ||
>                      !device_property_read_bool(dwc->dev, "usb-role-switch")) &&
>                     !DWC3_VER_IS_PRIOR(DWC3, 330A))
> @@ -1715,6 +1715,13 @@ static int dwc3_probe(struct platform_device *pdev)
>                 goto err2;
>         }
>
> +       dwc->edev = dwc3_get_extcon(dwc);
> +       if (IS_ERR(dwc->edev)) {
> +               ret = PTR_ERR(dwc->edev);
> +               dev_err(dwc->dev, "failed to get extcon %d\n", ret);
> +               goto err3;
> +       }
> +
>         ret = dwc3_get_dr_mode(dwc);
>         if (ret)
>                 goto err3;
> diff --git a/drivers/usb/dwc3/drd.c b/drivers/usb/dwc3/drd.c
> index 63089c7fb530..d02fcfdc74db 100644
> --- a/drivers/usb/dwc3/drd.c
> +++ b/drivers/usb/dwc3/drd.c
> @@ -585,16 +585,7 @@ int dwc3_drd_init(struct dwc3 *dwc)
>  {
>         int ret, irq;
>
> -       dwc->edev = dwc3_get_extcon(dwc);
> -       if (IS_ERR(dwc->edev))
> -               return PTR_ERR(dwc->edev);
> -
> -       if (ROLE_SWITCH &&
> -           device_property_read_bool(dwc->dev, "usb-role-switch")) {
> -               ret = dwc3_setup_role_switch(dwc);
> -               if (ret < 0)
> -                       return ret;
> -       } else if (dwc->edev) {

We probably don't even need to move this around. If "usb-role-switch"
isn't going to be set then that "if" could go first and not interfere.

> +       if (dwc->edev) {
>                 dwc->edev_nb.notifier_call = dwc3_drd_notifier;
>                 ret = extcon_register_notifier(dwc->edev, EXTCON_USB_HOST,
>                                                &dwc->edev_nb);
> @@ -604,6 +595,11 @@ int dwc3_drd_init(struct dwc3 *dwc)
>                 }
>
>                 dwc3_drd_update(dwc);
> +       } else if (ROLE_SWITCH &&
> +                  device_property_read_bool(dwc->dev, "usb-role-switch")) {
> +               ret = dwc3_setup_role_switch(dwc);
> +               if (ret < 0)
> +                       return ret;
>         } else {
>                 dwc3_set_prtcap(dwc, DWC3_GCTL_PRTCAP_OTG);
>
>

Andrey Smirnov wrote:
> On Wed, Feb 2, 2022 at 6:54 PM Thinh Nguyen <Thinh.Nguyen@synopsys.com> wrote:
>>
>> Andrey Smirnov wrote:
>>> It is necessary that:
>>>
>>>    ROLE_SWITCH && device_property_read_bool(dwc->dev, "usb-role-switch")
>>>
>>> is true in order for dwc3_get_dr_mode() to _not_ force us from OTG to
>>> PERIPHERAL mode here:
>>>
>>>    if (mode == USB_DR_MODE_OTG &&
>>>        (!IS_ENABLED(CONFIG_USB_ROLE_SWITCH) ||
>>>         !device_property_read_bool(dwc->dev, "usb-role-switch")) &&
>>>       !DWC3_VER_IS_PRIOR(DWC3, 330A))
>>>       mode = USB_DR_MODE_PERIPHERAL;
>>>
>>> and dwc3_drd_init() to be called later in dwc3_core_init_mode(). So,
>>> to avoid always ignoring extcon device returned by dwc3_get_extcon()
>>> change dwc3_drd_init() to check and use it first, before checking if
>>> dwc3_setup_role_switch() should be called.
>>>
>>> Cc: Felipe Balbi <balbi@kernel.org>
>>> Cc: Thinh Nguyen <thinhn@synopsys.com>
>>> Cc: linux-usb@vger.kernel.org
>>> Cc: linux-kernel@vger.kernel.org
>>> Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
>>> ---
>>>
>>> Hopefully I didn't miss something important making this patch
>>> unnecessary. Don't know if this is a good solution or not, part of me
>>> thinks than maybe changing the aforementioned code in
>>> dwc3_get_dr_mode() to account for extcon wopuld be
>>> simpler/better. Happy to rework this.
>>
>> The driver either use extcon or usb-role-switch. It doesn't make sense to
>> enable usb-role-switch for extcon just so the driver doesn't default
>> the dr_mode to peripheral.
>>
>> Perhaps, this is what you're looking for? (code is not tested)
>>
> 
> Yeah that kind of what I meant by "maybe changing the aforementioned code in
> dwc3_get_dr_mode() to account for extcon wopuld be
> simpler/better." OK let me rework the patch to do that.
> 
>> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
>> index bffd719b8b52..a52331ea7a0d 100644
>> --- a/drivers/usb/dwc3/core.c
>> +++ b/drivers/usb/dwc3/core.c
>> @@ -86,7 +86,7 @@ static int dwc3_get_dr_mode(struct dwc3 *dwc)
>>                  * mode. If the controller supports DRD but the dr_mode is not
>>                  * specified or set to OTG, then set the mode to peripheral.
>>                  */
>> -               if (mode == USB_DR_MODE_OTG &&
>> +               if (mode == USB_DR_MODE_OTG && !dwc->edev &&
>>                     (!IS_ENABLED(CONFIG_USB_ROLE_SWITCH) ||
>>                      !device_property_read_bool(dwc->dev, "usb-role-switch")) &&
>>                     !DWC3_VER_IS_PRIOR(DWC3, 330A))
>> @@ -1715,6 +1715,13 @@ static int dwc3_probe(struct platform_device *pdev)
>>                 goto err2;
>>         }
>>
>> +       dwc->edev = dwc3_get_extcon(dwc);
>> +       if (IS_ERR(dwc->edev)) {
>> +               ret = PTR_ERR(dwc->edev);
>> +               dev_err(dwc->dev, "failed to get extcon %d\n", ret);
>> +               goto err3;
>> +       }
>> +
>>         ret = dwc3_get_dr_mode(dwc);
>>         if (ret)
>>                 goto err3;
>> diff --git a/drivers/usb/dwc3/drd.c b/drivers/usb/dwc3/drd.c
>> index 63089c7fb530..d02fcfdc74db 100644
>> --- a/drivers/usb/dwc3/drd.c
>> +++ b/drivers/usb/dwc3/drd.c
>> @@ -585,16 +585,7 @@ int dwc3_drd_init(struct dwc3 *dwc)
>>  {
>>         int ret, irq;
>>
>> -       dwc->edev = dwc3_get_extcon(dwc);
>> -       if (IS_ERR(dwc->edev))
>> -               return PTR_ERR(dwc->edev);
>> -
>> -       if (ROLE_SWITCH &&
>> -           device_property_read_bool(dwc->dev, "usb-role-switch")) {
>> -               ret = dwc3_setup_role_switch(dwc);
>> -               if (ret < 0)
>> -                       return ret;
>> -       } else if (dwc->edev) {
> 
> We probably don't even need to move this around. If "usb-role-switch"
> isn't going to be set then that "if" could go first and not interfere.
> 

Yeah, this is unnecessary.

>> +       if (dwc->edev) {
>>                 dwc->edev_nb.notifier_call = dwc3_drd_notifier;
>>                 ret = extcon_register_notifier(dwc->edev, EXTCON_USB_HOST,
>>                                                &dwc->edev_nb);
>> @@ -604,6 +595,11 @@ int dwc3_drd_init(struct dwc3 *dwc)
>>                 }
>>
>>                 dwc3_drd_update(dwc);
>> +       } else if (ROLE_SWITCH &&
>> +                  device_property_read_bool(dwc->dev, "usb-role-switch")) {
>> +               ret = dwc3_setup_role_switch(dwc);
>> +               if (ret < 0)
>> +                       return ret;
>>         } else {
>>                 dwc3_set_prtcap(dwc, DWC3_GCTL_PRTCAP_OTG);
>>
>>

Thanks,
Thinh