linux-kernel - Re: [PATCH v5 1/2] phy: Add new PHY attribute max_link

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Date:   Wed, 2 Sep 2020 03:26:08 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Swapnil Jakhade <sjakhade@...ence.com>
Cc:     vkoul@...nel.org, kishon@...com, linux-kernel@...r.kernel.org,
        maxime@...no.tech, mparab@...ence.com, yamonkar@...ence.com,
        nsekhar@...com, tomi.valkeinen@...com, jsarha@...com,
        praneeth@...com
Subject: Re: [PATCH v5 1/2] phy: Add new PHY attribute max_link_rate and APIs
 to get/set PHY attributes

Hi Swapnil,

Thank you for the patch.

On Mon, Aug 24, 2020 at 08:28:30PM +0200, Swapnil Jakhade wrote:
> Add new PHY attribute max_link_rate to struct phy_attrs.
> Add a pair of PHY APIs to get/set all the PHY attributes.
> Use phy_get_attrs() to get attribute values and phy_set_attrs()
> to set attribute values.
> 
> Signed-off-by: Yuti Amonkar <yamonkar@...ence.com>
> Signed-off-by: Swapnil Jakhade <sjakhade@...ence.com>
> Acked-by: Kishon Vijay Abraham I <kishon@...com>
> ---
>  include/linux/phy/phy.h | 43 +++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 43 insertions(+)
> 
> diff --git a/include/linux/phy/phy.h b/include/linux/phy/phy.h
> index bcee8eba62b3..924cd1a3deea 100644
> --- a/include/linux/phy/phy.h
> +++ b/include/linux/phy/phy.h
> @@ -115,10 +115,12 @@ struct phy_ops {
>  /**
>   * struct phy_attrs - represents phy attributes
>   * @bus_width: Data path width implemented by PHY
> + * @max_link_rate: Maximum link rate supported by PHY (in Mbps)
>   * @mode: PHY mode
>   */
>  struct phy_attrs {
>  	u32			bus_width;
> +	u32			max_link_rate;
>  	enum phy_mode		mode;
>  };
>  
> @@ -231,6 +233,37 @@ static inline void phy_set_bus_width(struct phy *phy, int bus_width)
>  {
>  	phy->attrs.bus_width = bus_width;
>  }
> +
> +/**
> + * phy_get_attrs() - get the values for PHY attributes.
> + * @phy: the phy for which to get the attributes
> + * @attrs: current PHY attributes that will be returned
> + *
> + * Intended to be used by phy consumers to get the current PHY attributes
> + * stored in struct phy_attrs.
> + */
> +static inline void phy_get_attrs(struct phy *phy, struct phy_attrs *attrs)
> +{
> +	mutex_lock(&phy->mutex);
> +	memcpy(attrs, &phy->attrs, sizeof(struct phy_attrs));
> +	mutex_unlock(&phy->mutex);

Why is the mutex required, what does it guard against ?

> +}
> +
> +/**
> + * phy_set_attrs() - set PHY attributes with new values.
> + * @phy: the phy for which to set the attributes
> + * @attrs: the &struct phy_attrs containing new PHY attributes to be set
> + *
> + * This can be used by PHY providers or PHY consumers to set the PHY
> + * attributes. The locking is used to protect updating attributes when
> + * PHY consumer is doing some PHY ops.
> + */
> +static inline void phy_set_attrs(struct phy *phy, const struct phy_attrs *attrs)
> +{
> +	mutex_lock(&phy->mutex);
> +	memcpy(&phy->attrs, attrs, sizeof(struct phy_attrs));
> +	mutex_unlock(&phy->mutex);
> +}
>  struct phy *phy_get(struct device *dev, const char *string);
>  struct phy *phy_optional_get(struct device *dev, const char *string);
>  struct phy *devm_phy_get(struct device *dev, const char *string);
> @@ -389,6 +422,16 @@ static inline void phy_set_bus_width(struct phy *phy, int bus_width)
>  	return;
>  }
>  
> +static inline void phy_get_attrs(struct phy *phy, struct phy_attrs *attrs)
> +{
> +	return;

You can drop the return statement.

> +}
> +
> +static inline void phy_set_attrs(struct phy *phy, const struct phy_attrs *attrs)
> +{
> +	return;

Here too.

> +}
> +
>  static inline struct phy *phy_get(struct device *dev, const char *string)
>  {
>  	return ERR_PTR(-ENOSYS);

-- 
Regards,

Laurent Pinchart