Re: [PATCH net-next v3 03/13] net: phy: phy_caps: Move phy_speeds to phy_caps

["Russell King (Oracle)" <linux@armlinux.org.uk>]

On Fri, Feb 28, 2025 at 03:55:28PM +0100, Maxime Chevallier wrote:
> Use the newly introduced link_capabilities array to derive the list of
> possible speeds when given a combination of linkmodes. As
> link_capabilities is indexed by speed, we don't have to iterate the
> whole phy_settings array.
> 
> Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
> ---
>  drivers/net/phy/phy-caps.h |  3 +++
>  drivers/net/phy/phy-core.c | 15 ---------------
>  drivers/net/phy/phy.c      |  3 ++-
>  drivers/net/phy/phy_caps.c | 27 +++++++++++++++++++++++++++
>  include/linux/phy.h        |  2 --
>  5 files changed, 32 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/net/phy/phy-caps.h b/drivers/net/phy/phy-caps.h
> index 846d483269f6..f8cdfdb09242 100644
> --- a/drivers/net/phy/phy-caps.h
> +++ b/drivers/net/phy/phy-caps.h
> @@ -41,4 +41,7 @@ struct link_capabilities {
>  
>  void phy_caps_init(void);
>  
> +size_t phy_caps_speeds(unsigned int *speeds, size_t size,
> +		       unsigned long *linkmodes);
> +
>  #endif /* __PHY_CAPS_H */
> diff --git a/drivers/net/phy/phy-core.c b/drivers/net/phy/phy-core.c
> index b1c1670de23b..8533e57c3500 100644
> --- a/drivers/net/phy/phy-core.c
> +++ b/drivers/net/phy/phy-core.c
> @@ -339,21 +339,6 @@ phy_lookup_setting(int speed, int duplex, const unsigned long *mask, bool exact)
>  }
>  EXPORT_SYMBOL_GPL(phy_lookup_setting);
>  
> -size_t phy_speeds(unsigned int *speeds, size_t size,
> -		  unsigned long *mask)
> -{
> -	size_t count;
> -	int i;
> -
> -	for (i = 0, count = 0; i < ARRAY_SIZE(settings) && count < size; i++)
> -		if (settings[i].bit < __ETHTOOL_LINK_MODE_MASK_NBITS &&
> -		    test_bit(settings[i].bit, mask) &&
> -		    (count == 0 || speeds[count - 1] != settings[i].speed))
> -			speeds[count++] = settings[i].speed;
> -
> -	return count;
> -}
> -
>  static void __set_linkmode_max_speed(u32 max_speed, unsigned long *addr)
>  {
>  	const struct phy_setting *p;
> diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
> index 16ffc00b419c..3128df03feda 100644
> --- a/drivers/net/phy/phy.c
> +++ b/drivers/net/phy/phy.c
> @@ -37,6 +37,7 @@
>  #include <net/sock.h>
>  
>  #include "phylib-internal.h"
> +#include "phy-caps.h"
>  
>  #define PHY_STATE_TIME	HZ
>  
> @@ -245,7 +246,7 @@ unsigned int phy_supported_speeds(struct phy_device *phy,
>  				  unsigned int *speeds,
>  				  unsigned int size)
>  {
> -	return phy_speeds(speeds, size, phy->supported);
> +	return phy_caps_speeds(speeds, size, phy->supported);
>  }
>  
>  /**
> diff --git a/drivers/net/phy/phy_caps.c b/drivers/net/phy/phy_caps.c
> index 367ca7110ddc..e5c716365b36 100644
> --- a/drivers/net/phy/phy_caps.c
> +++ b/drivers/net/phy/phy_caps.c
> @@ -76,3 +76,30 @@ void phy_caps_init(void)
>  		__set_bit(i, link_caps[capa].linkmodes);
>  	}
>  }
> +
> +/**
> + * phy_caps_speeds() - Fill an array of supported SPEED_* values for given modes
> + * @speeds: Output array to store the speeds list into
> + * @size: Size of the output array
> + * @linkmodes: Linkmodes to get the speeds from
> + *
> + * Fills the speeds array with all possible speeds that can be achieved with
> + * the specified linkmodes.
> + *
> + * Returns: The number of speeds filled into the array. If the input array isn't
> + *	    big enough to store all speeds, fill it as much as possible.
> + */
> +size_t phy_caps_speeds(unsigned int *speeds, size_t size,
> +		       unsigned long *linkmodes)
> +{
> +	size_t count;
> +	int capa;
> +
> +	for (capa = 0, count = 0; capa < __LINK_CAPA_MAX && count < size; capa++) {
> +		if (linkmode_intersects(link_caps[capa].linkmodes, linkmodes) &&
> +		    (count == 0 || speeds[count - 1] != link_caps[capa].speed))
> +			speeds[count++] = link_caps[capa].speed;
> +	}

Having looked at several of these patches, there's a common pattern
emerging, which is we're walking over link_caps in either ascending
speed order or descending speed order. So I wonder whether it would
make sense to have:

#define for_each_link_caps_asc_speed(cap) \
	for (cap = link_caps; cap < &link_caps[__LINK_CAPA_MAX]; cap++)
#define for_each_link_caps_desc_speed(cap) \
	for (cap = &link_caps[__LINK_CAPA_MAX - 1]; cap >= link_caps; cap--)

for where iterating over in speed order is important. E.g. this would
make the above:

	struct link_capabilities *lcap;

	for_each_link_caps_asc_speed(lcap)
		if (linkmode_intersects(lcap->linkmodes, linkmodes) &&
		    (count == 0 || speeds[count - 1] != lcap->speed)) {
			speeds[count++] = lcap->speed;
			if (count >= size)
				break;
		}

which helps to make it explicit that speeds[] is in ascending value
order.

-- 
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