Re: [PATCH] Revert "usb: cdns3: core: quit if it uses role switch class"

[Roger Quadros]

+Heikki

Peter,

On 24/11/2020 11:57, Peter Chen wrote:
> Best regards,
> Peter Chen
>
> > -----Original Message-----
> > From: Roger Quadros <rogerq@xxxxxx>
> > Sent: 2020年11月24日 17:39
> > To: Peter Chen <peter.chen@xxxxxxx>
> > Cc: pawell@xxxxxxxxxxx; gregkh@xxxxxxxxxxxxxxxxxxx; balbi@xxxxxxxxxx;
> > linux-usb@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> > Subject: Re: [PATCH] Revert "usb: cdns3: core: quit if it uses role switch class"
> >
> > Peter,
> >
> > On 24/11/2020 08:43, Peter Chen wrote:
> > > On 20-11-23 13:50:51, Roger Quadros wrote:
> > > > This reverts commit 50642709f6590fe40afa6d22c32f23f5b842aed5.
> > > >
> > > > This commit breaks hardware based role switching on TI platforms.
> > > > cdns->role_sw is always going to be non-zero as it is a pointer
> > > > to the usb_role_switch instance. Some other means needs to be used if
> > > > hardware based role switching is not required by the platform.
> > > >
> > > > Signed-off-by: Roger Quadros <rogerq@xxxxxx>
> > > > ---
> > > >    drivers/usb/cdns3/core.c | 4 ----
> > > >    1 file changed, 4 deletions(-)
> > > >
> > > > diff --git a/drivers/usb/cdns3/core.c b/drivers/usb/cdns3/core.c
> > > > index a0f73d4711ae..4c1445cf2ad0 100644
> > > > --- a/drivers/usb/cdns3/core.c
> > > > +++ b/drivers/usb/cdns3/core.c
> > > > @@ -280,10 +280,6 @@ int cdns3_hw_role_switch(struct cdns3 *cdns)
> > > >    	enum usb_role real_role, current_role;
> > > >    	int ret = 0;
> > > >
> > > > -	/* Depends on role switch class */
> > > > -	if (cdns->role_sw)
> > > > -		return 0;
> > > > -
> > > >    	pm_runtime_get_sync(cdns->dev);
> > > >
> > > >    	current_role = cdns->role;
> > > > --
> > >
> > > Hi Roger,
> > >
> > > I am sorry about that. Do you use role switch /sys entry, if you have
> > > used, I prefer using "usb-role-switch" property at dts to judge if SoC
> > > OTG signals or external signals for role switch. If you have not used
> > > it, I prefer only setting cdns->role_sw for role switch use cases.
> >
> > We use both hardware role switch and /sys entries for manually forcing a
> > certain role.
> >
> > We do not set any "usb-role-switch" property at DTS.
> >
> > Currently cdns->role_sw is being always set by driver irrespective of any DT
> > property, so this patch is clearly wrong and needs to be reverted.
> >
> > What do you think?
>
> Could you accept below fix?
>
> diff --git a/drivers/usb/cdns3/core.c b/drivers/usb/cdns3/core.c
> index 2e469139769f..fdd52e87a7b2 100644
> --- a/drivers/usb/cdns3/core.c
> +++ b/drivers/usb/cdns3/core.c
> @@ -280,8 +280,8 @@ int cdns3_hw_role_switch(struct cdns3 *cdns)
>          enum usb_role real_role, current_role;
>          int ret = 0;
>
> -       /* Depends on role switch class */
> -       if (cdns->role_sw)
> +       /* quit if switch role through external signals */
> +       if (device_property_read_bool(cdns->dev, "usb-role-switch"))
>                  return 0;
>
>          pm_runtime_get_sync(cdns->dev);

Although this will fix the issue I don't think this is making the driver to behave
as expected with usb-role-switch property.

Now, even if usb-role-switch property is not present the driver will still register
the role switch driver.

I think we need to register the role switch driver only if usb-role-switch property
is present. We would also need to set the default role if role-switch-default-mode is present.

How about the following? It still doesn't handle role-switch-default-mode property though.


diff --git a/drivers/usb/cdns3/core.c b/drivers/usb/cdns3/core.c
index 4c1445cf2ad0..986b56a9940c 100644
--- a/drivers/usb/cdns3/core.c
+++ b/drivers/usb/cdns3/core.c
@@ -532,11 +532,13 @@ static int cdns3_probe(struct platform_device *pdev)
 	if (device_property_read_bool(dev, "usb-role-switch"))
 		sw_desc.fwnode = dev->fwnode;
 
-	cdns->role_sw = usb_role_switch_register(dev, &sw_desc);
-	if (IS_ERR(cdns->role_sw)) {
-		ret = PTR_ERR(cdns->role_sw);
-		dev_warn(dev, "Unable to register Role Switch\n");
-		goto err3;
+	if (device_property_read_bool(cdns->dev, "usb-role-switch")) {
+		cdns->role_sw = usb_role_switch_register(dev, &sw_desc);
+		if (IS_ERR(cdns->role_sw)) {
+			ret = PTR_ERR(cdns->role_sw);
+			dev_warn(dev, "Unable to register Role Switch\n");
+			goto err3;
+		}
 	}
 
 	if (cdns->wakeup_irq) {



cheers,
-roger
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