Patchwork Revert "usb: dwc3: pci: Use devm functions to get the phy GPIOs"

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Submitter Stephan Gerhold
Date Dec. 6, 2018, 6:42 p.m.
Message ID <20181206184228.17666-1-stephan@gerhold.net>
Download mbox | patch
Permalink /patch/674557/
State New
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Comments

Stephan Gerhold - Dec. 6, 2018, 6:42 p.m.
Commit 211f658b7b40 ("usb: dwc3: pci: Use devm functions to get
the phy GPIOs") changed the code to claim the PHY GPIOs permanently
for Intel Baytrail devices.

This causes issues when the actual PHY driver attempts to claim the
same GPIO descriptors. For example, tusb1210 now fails to probe with:

  tusb1210: probe of dwc3.0.auto.ulpi failed with error -16 (EBUSY)

dwc3-pci needs to turn on the PHY once before dwc3 is loaded, but
usually the PHY driver will then hold the GPIOs to turn off the
PHY when requested (e.g. during suspend).

To fix the problem, this reverts the commit to restore the old
behavior to put the GPIOs immediately after usage.

Link: https://www.spinics.net/lists/linux-usb/msg174681.html
Cc: stable@vger.kernel.org
Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
---
 drivers/usb/dwc3/dwc3-pci.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
Hans de Goede - Dec. 9, 2018, 11:16 a.m.
Hi,

Thank you.

On 06-12-18 19:42, Stephan Gerhold wrote:
> Commit 211f658b7b40 ("usb: dwc3: pci: Use devm functions to get
> the phy GPIOs") changed the code to claim the PHY GPIOs permanently
> for Intel Baytrail devices.
> 
> This causes issues when the actual PHY driver attempts to claim the
> same GPIO descriptors. For example, tusb1210 now fails to probe with:
> 
>    tusb1210: probe of dwc3.0.auto.ulpi failed with error -16 (EBUSY)
> 
> dwc3-pci needs to turn on the PHY once before dwc3 is loaded, but
> usually the PHY driver will then hold the GPIOs to turn off the
> PHY when requested (e.g. during suspend).
> 
> To fix the problem, this reverts the commit to restore the old
> behavior to put the GPIOs immediately after usage.
> 
> Link: https://www.spinics.net/lists/linux-usb/msg174681.html
> Cc: stable@vger.kernel.org
> Signed-off-by: Stephan Gerhold <stephan@gerhold.net>

Right, the original change was done because I did not realize
that the phy driver would take over managing the GPIOs (and on
my test device it doesn't due to an unrelated issue).

So reverting this is the right thing to do:

Acked-by: Hans de Goede <hdegoede@redhat.com>

Regards,

Hans



> ---
>   drivers/usb/dwc3/dwc3-pci.c | 8 ++++----
>   1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/dwc3-pci.c b/drivers/usb/dwc3/dwc3-pci.c
> index 842795856bf4..fdc6e4e403e8 100644
> --- a/drivers/usb/dwc3/dwc3-pci.c
> +++ b/drivers/usb/dwc3/dwc3-pci.c
> @@ -170,20 +170,20 @@ static int dwc3_pci_quirks(struct dwc3_pci *dwc)
>   			 * put the gpio descriptors again here because the phy driver
>   			 * might want to grab them, too.
>   			 */
> -			gpio = devm_gpiod_get_optional(&pdev->dev, "cs",
> -						       GPIOD_OUT_LOW);
> +			gpio = gpiod_get_optional(&pdev->dev, "cs", GPIOD_OUT_LOW);
>   			if (IS_ERR(gpio))
>   				return PTR_ERR(gpio);
>   
>   			gpiod_set_value_cansleep(gpio, 1);
> +			gpiod_put(gpio);
>   
> -			gpio = devm_gpiod_get_optional(&pdev->dev, "reset",
> -						       GPIOD_OUT_LOW);
> +			gpio = gpiod_get_optional(&pdev->dev, "reset", GPIOD_OUT_LOW);
>   			if (IS_ERR(gpio))
>   				return PTR_ERR(gpio);
>   
>   			if (gpio) {
>   				gpiod_set_value_cansleep(gpio, 1);
> +				gpiod_put(gpio);
>   				usleep_range(10000, 11000);
>   			}
>   		}
>
Andy Shevchenko - Dec. 9, 2018, 2:44 p.m.
On Thu, Dec 6, 2018 at 8:49 PM Stephan Gerhold <stephan@gerhold.net> wrote:
>
> Commit 211f658b7b40 ("usb: dwc3: pci: Use devm functions to get
> the phy GPIOs") changed the code to claim the PHY GPIOs permanently
> for Intel Baytrail devices.
>
> This causes issues when the actual PHY driver attempts to claim the
> same GPIO descriptors. For example, tusb1210 now fails to probe with:
>
>   tusb1210: probe of dwc3.0.auto.ulpi failed with error -16 (EBUSY)
>
> dwc3-pci needs to turn on the PHY once before dwc3 is loaded, but
> usually the PHY driver will then hold the GPIOs to turn off the
> PHY when requested (e.g. during suspend).
>
> To fix the problem, this reverts the commit to restore the old
> behavior to put the GPIOs immediately after usage.
>
> Link: https://www.spinics.net/lists/linux-usb/msg174681.html
> Cc: stable@vger.kernel.org
> Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
> ---
>  drivers/usb/dwc3/dwc3-pci.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/usb/dwc3/dwc3-pci.c b/drivers/usb/dwc3/dwc3-pci.c
> index 842795856bf4..fdc6e4e403e8 100644
> --- a/drivers/usb/dwc3/dwc3-pci.c
> +++ b/drivers/usb/dwc3/dwc3-pci.c
> @@ -170,20 +170,20 @@ static int dwc3_pci_quirks(struct dwc3_pci *dwc)
>                          * put the gpio descriptors again here because the phy driver
>                          * might want to grab them, too.
>                          */
> -                       gpio = devm_gpiod_get_optional(&pdev->dev, "cs",
> -                                                      GPIOD_OUT_LOW);
> +                       gpio = gpiod_get_optional(&pdev->dev, "cs", GPIOD_OUT_LOW);
>                         if (IS_ERR(gpio))
>                                 return PTR_ERR(gpio);
>
>                         gpiod_set_value_cansleep(gpio, 1);
> +                       gpiod_put(gpio);
>
> -                       gpio = devm_gpiod_get_optional(&pdev->dev, "reset",
> -                                                      GPIOD_OUT_LOW);
> +                       gpio = gpiod_get_optional(&pdev->dev, "reset", GPIOD_OUT_LOW);
>                         if (IS_ERR(gpio))
>                                 return PTR_ERR(gpio);
>
>                         if (gpio) {
>                                 gpiod_set_value_cansleep(gpio, 1);

> +                               gpiod_put(gpio);
>                                 usleep_range(10000, 11000);

If something happens to GPIO line in between of these lines, the sleep
might become obsolete. Shouldn't gpiod_put() be placed after?

>                         }
>                 }
Hans de Goede - Dec. 9, 2018, 2:53 p.m.
Hi,

On 09-12-18 15:44, Andy Shevchenko wrote:
> On Thu, Dec 6, 2018 at 8:49 PM Stephan Gerhold <stephan@gerhold.net> wrote:
>>
>> Commit 211f658b7b40 ("usb: dwc3: pci: Use devm functions to get
>> the phy GPIOs") changed the code to claim the PHY GPIOs permanently
>> for Intel Baytrail devices.
>>
>> This causes issues when the actual PHY driver attempts to claim the
>> same GPIO descriptors. For example, tusb1210 now fails to probe with:
>>
>>    tusb1210: probe of dwc3.0.auto.ulpi failed with error -16 (EBUSY)
>>
>> dwc3-pci needs to turn on the PHY once before dwc3 is loaded, but
>> usually the PHY driver will then hold the GPIOs to turn off the
>> PHY when requested (e.g. during suspend).
>>
>> To fix the problem, this reverts the commit to restore the old
>> behavior to put the GPIOs immediately after usage.
>>
>> Link: https://www.spinics.net/lists/linux-usb/msg174681.html
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
>> ---
>>   drivers/usb/dwc3/dwc3-pci.c | 8 ++++----
>>   1 file changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/usb/dwc3/dwc3-pci.c b/drivers/usb/dwc3/dwc3-pci.c
>> index 842795856bf4..fdc6e4e403e8 100644
>> --- a/drivers/usb/dwc3/dwc3-pci.c
>> +++ b/drivers/usb/dwc3/dwc3-pci.c
>> @@ -170,20 +170,20 @@ static int dwc3_pci_quirks(struct dwc3_pci *dwc)
>>                           * put the gpio descriptors again here because the phy driver
>>                           * might want to grab them, too.
>>                           */
>> -                       gpio = devm_gpiod_get_optional(&pdev->dev, "cs",
>> -                                                      GPIOD_OUT_LOW);
>> +                       gpio = gpiod_get_optional(&pdev->dev, "cs", GPIOD_OUT_LOW);
>>                          if (IS_ERR(gpio))
>>                                  return PTR_ERR(gpio);
>>
>>                          gpiod_set_value_cansleep(gpio, 1);
>> +                       gpiod_put(gpio);
>>
>> -                       gpio = devm_gpiod_get_optional(&pdev->dev, "reset",
>> -                                                      GPIOD_OUT_LOW);
>> +                       gpio = gpiod_get_optional(&pdev->dev, "reset", GPIOD_OUT_LOW);
>>                          if (IS_ERR(gpio))
>>                                  return PTR_ERR(gpio);
>>
>>                          if (gpio) {
>>                                  gpiod_set_value_cansleep(gpio, 1);
> 
>> +                               gpiod_put(gpio);
>>                                  usleep_range(10000, 11000);
> 
> If something happens to GPIO line in between of these lines, the sleep
> might become obsolete. Shouldn't gpiod_put() be placed after?

The actual reading of the ULPI product and vendor IDs happens a whole
bunch of functions after the dwc3_pci_quirks() function runs, so the
assumption is that nothing touches the GPIO until the phy driver
loads.

Also the current version of this patch is a straight revert of my patch,
IOW the put allowing potential mucking with the GPIO before the
IDs are read is a pre-existing problem.

Regards,

Hans
Stephan Gerhold - Dec. 9, 2018, 3:07 p.m.
On Sun, Dec 09, 2018 at 04:44:16PM +0200, Andy Shevchenko wrote:
> On Thu, Dec 6, 2018 at 8:49 PM Stephan Gerhold <stephan@gerhold.net> wrote:
> >
> > Commit 211f658b7b40 ("usb: dwc3: pci: Use devm functions to get
> > the phy GPIOs") changed the code to claim the PHY GPIOs permanently
> > for Intel Baytrail devices.
> >
> > This causes issues when the actual PHY driver attempts to claim the
> > same GPIO descriptors. For example, tusb1210 now fails to probe with:
> >
> >   tusb1210: probe of dwc3.0.auto.ulpi failed with error -16 (EBUSY)
> >
> > dwc3-pci needs to turn on the PHY once before dwc3 is loaded, but
> > usually the PHY driver will then hold the GPIOs to turn off the
> > PHY when requested (e.g. during suspend).
> >
> > To fix the problem, this reverts the commit to restore the old
> > behavior to put the GPIOs immediately after usage.
> >
> > Link: https://www.spinics.net/lists/linux-usb/msg174681.html
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
> > ---
> >  drivers/usb/dwc3/dwc3-pci.c | 8 ++++----
> >  1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/usb/dwc3/dwc3-pci.c b/drivers/usb/dwc3/dwc3-pci.c
> > index 842795856bf4..fdc6e4e403e8 100644
> > --- a/drivers/usb/dwc3/dwc3-pci.c
> > +++ b/drivers/usb/dwc3/dwc3-pci.c
> > @@ -170,20 +170,20 @@ static int dwc3_pci_quirks(struct dwc3_pci *dwc)
> >                          * put the gpio descriptors again here because the phy driver
> >                          * might want to grab them, too.
> >                          */
> > -                       gpio = devm_gpiod_get_optional(&pdev->dev, "cs",
> > -                                                      GPIOD_OUT_LOW);
> > +                       gpio = gpiod_get_optional(&pdev->dev, "cs", GPIOD_OUT_LOW);
> >                         if (IS_ERR(gpio))
> >                                 return PTR_ERR(gpio);
> >
> >                         gpiod_set_value_cansleep(gpio, 1);
> > +                       gpiod_put(gpio);
> >
> > -                       gpio = devm_gpiod_get_optional(&pdev->dev, "reset",
> > -                                                      GPIOD_OUT_LOW);
> > +                       gpio = gpiod_get_optional(&pdev->dev, "reset", GPIOD_OUT_LOW);
> >                         if (IS_ERR(gpio))
> >                                 return PTR_ERR(gpio);
> >
> >                         if (gpio) {
> >                                 gpiod_set_value_cansleep(gpio, 1);
> 
> > +                               gpiod_put(gpio);
> >                                 usleep_range(10000, 11000);
> 
> If something happens to GPIO line in between of these lines, the sleep
> might become obsolete. Shouldn't gpiod_put() be placed after?

That's a good point, but I believe this would be more appropriately
fixed in a separate patch, since this is just an exact revert of
211f658b7b40 ("usb: dwc3: pci: Use devm functions to get the phy GPIOs")
(This is the way it was written when it was added to mainline 4 years 
ago...)

I can send a separate patch for this, or would you like to?

> 
> >                         }
> >                 }
> 
> 
> -- 
> With Best Regards,
> Andy Shevchenko
Hans de Goede - Dec. 9, 2018, 3:28 p.m.
Hi,

On 09-12-18 16:07, Stephan Gerhold wrote:
> On Sun, Dec 09, 2018 at 04:44:16PM +0200, Andy Shevchenko wrote:
>> On Thu, Dec 6, 2018 at 8:49 PM Stephan Gerhold <stephan@gerhold.net> wrote:
>>>
>>> Commit 211f658b7b40 ("usb: dwc3: pci: Use devm functions to get
>>> the phy GPIOs") changed the code to claim the PHY GPIOs permanently
>>> for Intel Baytrail devices.
>>>
>>> This causes issues when the actual PHY driver attempts to claim the
>>> same GPIO descriptors. For example, tusb1210 now fails to probe with:
>>>
>>>    tusb1210: probe of dwc3.0.auto.ulpi failed with error -16 (EBUSY)
>>>
>>> dwc3-pci needs to turn on the PHY once before dwc3 is loaded, but
>>> usually the PHY driver will then hold the GPIOs to turn off the
>>> PHY when requested (e.g. during suspend).
>>>
>>> To fix the problem, this reverts the commit to restore the old
>>> behavior to put the GPIOs immediately after usage.
>>>
>>> Link: https://www.spinics.net/lists/linux-usb/msg174681.html
>>> Cc: stable@vger.kernel.org
>>> Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
>>> ---
>>>   drivers/usb/dwc3/dwc3-pci.c | 8 ++++----
>>>   1 file changed, 4 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/drivers/usb/dwc3/dwc3-pci.c b/drivers/usb/dwc3/dwc3-pci.c
>>> index 842795856bf4..fdc6e4e403e8 100644
>>> --- a/drivers/usb/dwc3/dwc3-pci.c
>>> +++ b/drivers/usb/dwc3/dwc3-pci.c
>>> @@ -170,20 +170,20 @@ static int dwc3_pci_quirks(struct dwc3_pci *dwc)
>>>                           * put the gpio descriptors again here because the phy driver
>>>                           * might want to grab them, too.
>>>                           */
>>> -                       gpio = devm_gpiod_get_optional(&pdev->dev, "cs",
>>> -                                                      GPIOD_OUT_LOW);
>>> +                       gpio = gpiod_get_optional(&pdev->dev, "cs", GPIOD_OUT_LOW);
>>>                          if (IS_ERR(gpio))
>>>                                  return PTR_ERR(gpio);
>>>
>>>                          gpiod_set_value_cansleep(gpio, 1);
>>> +                       gpiod_put(gpio);
>>>
>>> -                       gpio = devm_gpiod_get_optional(&pdev->dev, "reset",
>>> -                                                      GPIOD_OUT_LOW);
>>> +                       gpio = gpiod_get_optional(&pdev->dev, "reset", GPIOD_OUT_LOW);
>>>                          if (IS_ERR(gpio))
>>>                                  return PTR_ERR(gpio);
>>>
>>>                          if (gpio) {
>>>                                  gpiod_set_value_cansleep(gpio, 1);
>>
>>> +                               gpiod_put(gpio);
>>>                                  usleep_range(10000, 11000);
>>
>> If something happens to GPIO line in between of these lines, the sleep
>> might become obsolete. Shouldn't gpiod_put() be placed after?
> 
> That's a good point, but I believe this would be more appropriately
> fixed in a separate patch, since this is just an exact revert of
> 211f658b7b40 ("usb: dwc3: pci: Use devm functions to get the phy GPIOs")
> (This is the way it was written when it was added to mainline 4 years
> ago...)
> 
> I can send a separate patch for this, or would you like to?

Properly fixing this would require releasing *both* GPIOs *after* the
ULPI vendor and product IDs have been read. Which will require adding
some generic callback just for this to the generic non platform/pci
specific dwc3 code. Which IMHO is not worth the trouble since in
practice this is not really a problem.

Regards,

Hans
Stephan Gerhold - Dec. 9, 2018, 4:46 p.m.
On Sun, Dec 09, 2018 at 04:28:07PM +0100, Hans de Goede wrote:
> Hi,
> 
> On 09-12-18 16:07, Stephan Gerhold wrote:
> > On Sun, Dec 09, 2018 at 04:44:16PM +0200, Andy Shevchenko wrote:
> > > On Thu, Dec 6, 2018 at 8:49 PM Stephan Gerhold <stephan@gerhold.net> wrote:
> > > > 
> > > > Commit 211f658b7b40 ("usb: dwc3: pci: Use devm functions to get
> > > > the phy GPIOs") changed the code to claim the PHY GPIOs permanently
> > > > for Intel Baytrail devices.
> > > > 
> > > > This causes issues when the actual PHY driver attempts to claim the
> > > > same GPIO descriptors. For example, tusb1210 now fails to probe with:
> > > > 
> > > >    tusb1210: probe of dwc3.0.auto.ulpi failed with error -16 (EBUSY)
> > > > 
> > > > dwc3-pci needs to turn on the PHY once before dwc3 is loaded, but
> > > > usually the PHY driver will then hold the GPIOs to turn off the
> > > > PHY when requested (e.g. during suspend).
> > > > 
> > > > To fix the problem, this reverts the commit to restore the old
> > > > behavior to put the GPIOs immediately after usage.
> > > > 
> > > > Link: https://www.spinics.net/lists/linux-usb/msg174681.html
> > > > Cc: stable@vger.kernel.org
> > > > Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
> > > > ---
> > > >   drivers/usb/dwc3/dwc3-pci.c | 8 ++++----
> > > >   1 file changed, 4 insertions(+), 4 deletions(-)
> > > > 
> > > > diff --git a/drivers/usb/dwc3/dwc3-pci.c b/drivers/usb/dwc3/dwc3-pci.c
> > > > index 842795856bf4..fdc6e4e403e8 100644
> > > > --- a/drivers/usb/dwc3/dwc3-pci.c
> > > > +++ b/drivers/usb/dwc3/dwc3-pci.c
> > > > @@ -170,20 +170,20 @@ static int dwc3_pci_quirks(struct dwc3_pci *dwc)
> > > >                           * put the gpio descriptors again here because the phy driver
> > > >                           * might want to grab them, too.
> > > >                           */
> > > > -                       gpio = devm_gpiod_get_optional(&pdev->dev, "cs",
> > > > -                                                      GPIOD_OUT_LOW);
> > > > +                       gpio = gpiod_get_optional(&pdev->dev, "cs", GPIOD_OUT_LOW);
> > > >                          if (IS_ERR(gpio))
> > > >                                  return PTR_ERR(gpio);
> > > > 
> > > >                          gpiod_set_value_cansleep(gpio, 1);
> > > > +                       gpiod_put(gpio);
> > > > 
> > > > -                       gpio = devm_gpiod_get_optional(&pdev->dev, "reset",
> > > > -                                                      GPIOD_OUT_LOW);
> > > > +                       gpio = gpiod_get_optional(&pdev->dev, "reset", GPIOD_OUT_LOW);
> > > >                          if (IS_ERR(gpio))
> > > >                                  return PTR_ERR(gpio);
> > > > 
> > > >                          if (gpio) {
> > > >                                  gpiod_set_value_cansleep(gpio, 1);
> > > 
> > > > +                               gpiod_put(gpio);
> > > >                                  usleep_range(10000, 11000);
> > > 
> > > If something happens to GPIO line in between of these lines, the sleep
> > > might become obsolete. Shouldn't gpiod_put() be placed after?
> > 
> > That's a good point, but I believe this would be more appropriately
> > fixed in a separate patch, since this is just an exact revert of
> > 211f658b7b40 ("usb: dwc3: pci: Use devm functions to get the phy GPIOs")
> > (This is the way it was written when it was added to mainline 4 years
> > ago...)
> > 
> > I can send a separate patch for this, or would you like to?
> 
> Properly fixing this would require releasing *both* GPIOs *after* the
> ULPI vendor and product IDs have been read. Which will require adding
> some generic callback just for this to the generic non platform/pci
> specific dwc3 code. Which IMHO is not worth the trouble since in
> practice this is not really a problem.

Hmm, yeah, I was thinking about a specific situation where it would have 
made a difference if both GPIOs were put after the delay (not after the
ULPI vendor/product IDs have been read). But now that I think about it
again, it does not make much sense... Never mind. (Maybe Andy has 
another comment here..)

> 
> Regards,
> 
> Hans
>

Patch

diff --git a/drivers/usb/dwc3/dwc3-pci.c b/drivers/usb/dwc3/dwc3-pci.c
index 842795856bf4..fdc6e4e403e8 100644
--- a/drivers/usb/dwc3/dwc3-pci.c
+++ b/drivers/usb/dwc3/dwc3-pci.c
@@ -170,20 +170,20 @@  static int dwc3_pci_quirks(struct dwc3_pci *dwc)
 			 * put the gpio descriptors again here because the phy driver
 			 * might want to grab them, too.
 			 */
-			gpio = devm_gpiod_get_optional(&pdev->dev, "cs",
-						       GPIOD_OUT_LOW);
+			gpio = gpiod_get_optional(&pdev->dev, "cs", GPIOD_OUT_LOW);
 			if (IS_ERR(gpio))
 				return PTR_ERR(gpio);
 
 			gpiod_set_value_cansleep(gpio, 1);
+			gpiod_put(gpio);
 
-			gpio = devm_gpiod_get_optional(&pdev->dev, "reset",
-						       GPIOD_OUT_LOW);
+			gpio = gpiod_get_optional(&pdev->dev, "reset", GPIOD_OUT_LOW);
 			if (IS_ERR(gpio))
 				return PTR_ERR(gpio);
 
 			if (gpio) {
 				gpiod_set_value_cansleep(gpio, 1);
+				gpiod_put(gpio);
 				usleep_range(10000, 11000);
 			}
 		}