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Re: [PATCH v4 3/7] phy: Add set_mode callback

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  Re: [PATCH v4 3/7] phy: Add set_mode callback Bin Liu <b-liu@ti.com> - 2016-05-04 20:20 +0200
    Re: [PATCH v4 3/7] phy: Add set_mode callback David Lechner <david@lechnology.com> - 2016-05-04 20:30 +0200
      Re: [PATCH v4 3/7] phy: Add set_mode callback Bin Liu <b-liu@ti.com> - 2016-05-04 20:50 +0200
        Re: [PATCH v4 3/7] phy: Add set_mode callback David Lechner <david@lechnology.com> - 2016-05-04 21:50 +0200
        Re: [PATCH v4 3/7] phy: Add set_mode callback David Lechner <david@lechnology.com> - 2016-05-10 00:50 +0200

#1394595 — Re: [PATCH v4 3/7] phy: Add set_mode callback

Hi,

On Thu, Apr 14, 2016 at 01:35:14PM -0500, David Lechner wrote:
> The initial use for this is for PHYs that have a mode related to USB OTG.
> There are several SoCs (e.g. TI OMAP and DA8xx) that have a mode setting
> in the USB PHY to override OTG VBUS and ID signals.
> 
> Of course, the enum can be expaned in the future to include modes for
> other types of PHYs as well.
> 
> Suggested-by: Kishon Vijay Abraham I <kishon@ti.com>
> Signed-off-by: David Lechner <david@lechnology.com>
> ---
> 
> v4 changes:
> 
> * This is a new patch to avoid exporting a symbol from the phy-da8xx-usb driver.
> 
> 
>  drivers/phy/phy-core.c  | 15 +++++++++++++++
>  include/linux/phy/phy.h | 15 +++++++++++++++
>  2 files changed, 30 insertions(+)
> 
> diff --git a/drivers/phy/phy-core.c b/drivers/phy/phy-core.c
> index e7e574d..fe0344c 100644
> --- a/drivers/phy/phy-core.c
> +++ b/drivers/phy/phy-core.c
> @@ -342,6 +342,21 @@ int phy_power_off(struct phy *phy)
>  }
>  EXPORT_SYMBOL_GPL(phy_power_off);
>  
> +int phy_set_mode(struct phy *phy, enum phy_mode mode)
> +{
> +	int ret;
> +
> +	if (!phy || !phy->ops->set_mode)
> +		return 0;
> +
> +	mutex_lock(&phy->mutex);
> +	ret = phy->ops->set_mode(phy, mode);
> +	mutex_unlock(&phy->mutex);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(phy_set_mode);

Sorry for my late comments, have been busy on other things.

As I commented in v2, isn't it a better idea to not adding this callback
and let the da8xx phy driver set the mode register in _probe() based on
DT dr_mode?

musb core only calls the *optional* _set_mode() during init, so I don't
see any problem if the phy set the mode in its probe. 

Regards,
-Bin.

> +
>  /**
>   * _of_phy_get() - lookup and obtain a reference to a phy by phandle
>   * @np: device_node for which to get the phy
> diff --git a/include/linux/phy/phy.h b/include/linux/phy/phy.h
> index 8cf05e3..d66f4d9 100644
> --- a/include/linux/phy/phy.h
> +++ b/include/linux/phy/phy.h
> @@ -22,12 +22,20 @@
>  
>  struct phy;
>  
> +enum phy_mode {
> +	PHY_MODE_INVALID,
> +	PHY_MODE_USB_HOST,
> +	PHY_MODE_USB_DEVICE,
> +	PHY_MODE_USB_OTG,
> +};
> +
>  /**
>   * struct phy_ops - set of function pointers for performing phy operations
>   * @init: operation to be performed for initializing phy
>   * @exit: operation to be performed while exiting
>   * @power_on: powering on the phy
>   * @power_off: powering off the phy
> + * @set_mode: set the mode of the phy
>   * @owner: the module owner containing the ops
>   */
>  struct phy_ops {
> @@ -35,6 +43,7 @@ struct phy_ops {
>  	int	(*exit)(struct phy *phy);
>  	int	(*power_on)(struct phy *phy);
>  	int	(*power_off)(struct phy *phy);
> +	int	(*set_mode)(struct phy *phy, enum phy_mode mode);
>  	struct module *owner;
>  };
>  
> @@ -119,6 +128,7 @@ int phy_init(struct phy *phy);
>  int phy_exit(struct phy *phy);
>  int phy_power_on(struct phy *phy);
>  int phy_power_off(struct phy *phy);
> +int phy_set_mode(struct phy *phy, enum phy_mode mode);
>  static inline int phy_get_bus_width(struct phy *phy)
>  {
>  	return phy->attrs.bus_width;
> @@ -224,6 +234,13 @@ static inline int phy_power_off(struct phy *phy)
>     return -ENOSYS;
>  }
>  
> +static inline int phy_set_mode(struct phy *phy, enum phy_mode mode)
> +{
> +	if (!phy)
> +		return 0;
> +	return -ENOSYS;
> +}
> +
>  static inline int phy_get_bus_width(struct phy *phy)
>  {
>     return -ENOSYS;
> -- 
> 1.9.1
> 

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#1394605

On 05/04/2016 01:10 PM, Bin Liu wrote:
> Hi,
>
> On Thu, Apr 14, 2016 at 01:35:14PM -0500, David Lechner wrote:
>> The initial use for this is for PHYs that have a mode related to USB OTG.
>> There are several SoCs (e.g. TI OMAP and DA8xx) that have a mode setting
>> in the USB PHY to override OTG VBUS and ID signals.
>>
>> Of course, the enum can be expaned in the future to include modes for
>> other types of PHYs as well.
>>
>> Suggested-by: Kishon Vijay Abraham I <kishon@ti.com>
>> Signed-off-by: David Lechner <david@lechnology.com>
>> ---
>>
>> v4 changes:
>>
>> * This is a new patch to avoid exporting a symbol from the phy-da8xx-usb driver.
>>
>>
>>   drivers/phy/phy-core.c  | 15 +++++++++++++++
>>   include/linux/phy/phy.h | 15 +++++++++++++++
>>   2 files changed, 30 insertions(+)
>>
>> diff --git a/drivers/phy/phy-core.c b/drivers/phy/phy-core.c
>> index e7e574d..fe0344c 100644
>> --- a/drivers/phy/phy-core.c
>> +++ b/drivers/phy/phy-core.c
>> @@ -342,6 +342,21 @@ int phy_power_off(struct phy *phy)
>>   }
>>   EXPORT_SYMBOL_GPL(phy_power_off);
>>
>> +int phy_set_mode(struct phy *phy, enum phy_mode mode)
>> +{
>> +	int ret;
>> +
>> +	if (!phy || !phy->ops->set_mode)
>> +		return 0;
>> +
>> +	mutex_lock(&phy->mutex);
>> +	ret = phy->ops->set_mode(phy, mode);
>> +	mutex_unlock(&phy->mutex);
>> +
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(phy_set_mode);
>
> Sorry for my late comments, have been busy on other things.
>
> As I commented in v2, isn't it a better idea to not adding this callback
> and let the da8xx phy driver set the mode register in _probe() based on
> DT dr_mode?
>
> musb core only calls the *optional* _set_mode() during init, so I don't
> see any problem if the phy set the mode in its probe.
>
> Regards,
> -Bin.
>

As was already discussed, the mode can be changed via sysfs as well as 
during probe, so this callback is needed for that case.

This is something I actually plan on using because the device I am using 
(LEGO MINDSTORMS EV3) is not wired for OTG, so the callback is needed to 
override the ID and VBUS signals when switching between host and 
peripheral mode.

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#1394626

On Wed, May 04, 2016 at 01:20:36PM -0500, David Lechner wrote:
> On 05/04/2016 01:10 PM, Bin Liu wrote:
> >Hi,
> >
> >On Thu, Apr 14, 2016 at 01:35:14PM -0500, David Lechner wrote:
> >>The initial use for this is for PHYs that have a mode related to USB OTG.
> >>There are several SoCs (e.g. TI OMAP and DA8xx) that have a mode setting
> >>in the USB PHY to override OTG VBUS and ID signals.
> >>
> >>Of course, the enum can be expaned in the future to include modes for
> >>other types of PHYs as well.
> >>
> >>Suggested-by: Kishon Vijay Abraham I <kishon@ti.com>
> >>Signed-off-by: David Lechner <david@lechnology.com>
> >>---
> >>
> >>v4 changes:
> >>
> >>* This is a new patch to avoid exporting a symbol from the phy-da8xx-usb driver.
> >>
> >>
> >>  drivers/phy/phy-core.c  | 15 +++++++++++++++
> >>  include/linux/phy/phy.h | 15 +++++++++++++++
> >>  2 files changed, 30 insertions(+)
> >>
> >>diff --git a/drivers/phy/phy-core.c b/drivers/phy/phy-core.c
> >>index e7e574d..fe0344c 100644
> >>--- a/drivers/phy/phy-core.c
> >>+++ b/drivers/phy/phy-core.c
> >>@@ -342,6 +342,21 @@ int phy_power_off(struct phy *phy)
> >>  }
> >>  EXPORT_SYMBOL_GPL(phy_power_off);
> >>
> >>+int phy_set_mode(struct phy *phy, enum phy_mode mode)
> >>+{
> >>+	int ret;
> >>+
> >>+	if (!phy || !phy->ops->set_mode)
> >>+		return 0;
> >>+
> >>+	mutex_lock(&phy->mutex);
> >>+	ret = phy->ops->set_mode(phy, mode);
> >>+	mutex_unlock(&phy->mutex);
> >>+
> >>+	return ret;
> >>+}
> >>+EXPORT_SYMBOL_GPL(phy_set_mode);
> >
> >Sorry for my late comments, have been busy on other things.
> >
> >As I commented in v2, isn't it a better idea to not adding this callback
> >and let the da8xx phy driver set the mode register in _probe() based on
> >DT dr_mode?
> >
> >musb core only calls the *optional* _set_mode() during init, so I don't
> >see any problem if the phy set the mode in its probe.
> >
> >Regards,
> >-Bin.
> >
> 
> As was already discussed, the mode can be changed via sysfs as well
> as during probe, so this callback is needed for that case.

Ahh, it seems we have discussed this... I keep forgetting things...

> 
> This is something I actually plan on using because the device I am
> using (LEGO MINDSTORMS EV3) is not wired for OTG, so the callback is
> needed to override the ID and VBUS signals when switching between
> host and peripheral mode.

Have you already tested this? I never tried changing mode via sysfs, but
by quickly reviewing the code, I am wondering how it works. the core
only calls ops->set_mode() but nothing else. To really switch the mode,
the driver has to talk to the root hub, and manipulate the SESSION
bit...

Regards,
-Bin.

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#1394675

On 05/04/2016 01:39 PM, Bin Liu wrote:
>
> Have you already tested this? I never tried changing mode via sysfs, but
> by quickly reviewing the code, I am wondering how it works. the core
> only calls ops->set_mode() but nothing else. To really switch the mode,
> the driver has to talk to the root hub, and manipulate the SESSION
> bit...
>
> Regards,
> -Bin.
>


I haven't actually tried this. I need to hack together a USB cable to 
test it in host mode (Mini-B to Mini-B w/ powered hub).

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#1397488

On 05/04/2016 01:39 PM, Bin Liu wrote:
> On Wed, May 04, 2016 at 01:20:36PM -0500, David Lechner wrote:
>> This is something I actually plan on using because the device I am
>> using (LEGO MINDSTORMS EV3) is not wired for OTG, so the callback is
>> needed to override the ID and VBUS signals when switching between
>> host and peripheral mode.
>
> Have you already tested this? I never tried changing mode via sysfs, but
> by quickly reviewing the code, I am wondering how it works. the core
> only calls ops->set_mode() but nothing else. To really switch the mode,
> the driver has to talk to the root hub, and manipulate the SESSION
> bit...
>

I have tested this now and it works. It works because by setting the 
mode, we are overriding the VBUS and ID signals, which in turn triggers 
interrupts. I have tested switching to both peripheral mode and host 
mode via sysfs. Host mode has some issues if you are using a 
self-powered device, but that is a bug in the da8xx glue layer and 
shouldn't hold up this patch series. Aside from that, it works exactly 
as expected.

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