Re: [PATCH v4 07/23] usb: common: add API to get usb otg features from device tree

[Roger Quadros <rogerq-l0cyMroinI0@public.gmane.org>]

On Wed, 17 Jun 2015 13:43:39 +0800
Li Jun <jun.li-KZfg59tc24xl57MIdRCFDg@public.gmane.org> wrote:

> Check property of usb hardware to get otg version and if SRP, HNP and ADP
> are supported.
> 
> Signed-off-by: Li Jun <jun.li-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
> ---
>  drivers/usb/common/common.c | 29 +++++++++++++++++++++++++++++
>  include/linux/usb/of.h      |  7 +++++++
>  2 files changed, 36 insertions(+)
> 
> diff --git a/drivers/usb/common/common.c b/drivers/usb/common/common.c
> index b530fd4..b846172 100644
> --- a/drivers/usb/common/common.c
> +++ b/drivers/usb/common/common.c
> @@ -154,6 +154,35 @@ bool of_usb_host_tpl_support(struct device_node *np)
>  	return false;
>  }
>  EXPORT_SYMBOL_GPL(of_usb_host_tpl_support);
> +
> +/**
> + * of_usb_get_otg_caps - to get usb otg capabilities according to
> + * the passed properties in DT.
> + * @np: Pointer to the given device_node
> + * @otg_caps: Pointer to the target usb_otg_caps to be set
> + *
> + * The function gets and sets the otg capabilities
> + */
> +void of_usb_get_otg_caps(struct device_node *np, struct usb_otg_caps *otg_caps)
> +{
> +	u32 otg_rev;
> +
> +	if (!otg_caps)
> +		return;
> +
> +	if (!of_property_read_u32(np, "otg-rev", &otg_rev)) {
> +		otg_caps->otg_rev = otg_rev;
> +		if (!of_find_property(np, "hnp-disable", NULL))
> +			otg_caps->hnp_support = true;
> +		if (!of_find_property(np, "srp-disable", NULL))
> +			otg_caps->hnp_support = true;

srp_support = true;

> +		if (!of_find_property(np, "adp-disable", NULL) &&
> +					(otg_caps->otg_rev >= 0x0200))
> +			otg_caps->hnp_support = true;

adp_support = true;

> +	}

I think we are loosing information here.
The DT disable flags get changed to enable flags (xyz_support)
and after this we can't really tell if the device tree really
wanted us to disable the feature or enable it based on
otg_rev/controller capabilities.

Why not pass controller caps in otg_caps and then disable the
flags if requested from DT?
	if (of_find_property(np, "foo-disbale", NULL))
		otg_caps->foo_support = false;

The controller can still override anything afterwards
if it things something is wrong.
My guess is most controllers won't have to.

> +}
> +EXPORT_SYMBOL_GPL(of_usb_get_otg_caps);
> +
>  #endif
>  
>  MODULE_LICENSE("GPL");
> diff --git a/include/linux/usb/of.h b/include/linux/usb/of.h
> index cfe0528..bbf302b9 100644
> --- a/include/linux/usb/of.h
> +++ b/include/linux/usb/of.h
> @@ -15,6 +15,8 @@
>  enum usb_dr_mode of_usb_get_dr_mode(struct device_node *np);
>  enum usb_device_speed of_usb_get_maximum_speed(struct device_node *np);
>  bool of_usb_host_tpl_support(struct device_node *np);
> +void of_usb_get_otg_caps(struct device_node *np,
> +			struct usb_otg_caps *otg_caps);
>  #else
>  static inline enum usb_dr_mode of_usb_get_dr_mode(struct device_node *np)
>  {
> @@ -30,6 +32,11 @@ static inline bool of_usb_host_tpl_support(struct device_node *np)
>  {
>  	return false;
>  }
> +static inline void of_usb_get_otg_caps(struct device_node *np,
> +				struct usb_otg_caps *otg_caps)
> +{
> +
> +}
>  #endif
>  
>  #if IS_ENABLED(CONFIG_OF) && IS_ENABLED(CONFIG_USB_SUPPORT)

cheers,
-roger
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