On Wed, Jun 17, 2020 at 10:45:33PM +0530, Calvin Johnson wrote:
> From: Jeremy Linton <jeremy.lin...@arm.com>
>
> The mdiobus_scan logic is currently hardcoded to only
> work with c22 devices. This works fairly well in most
> cases, but its possible a c45 device doesn't respond
> despite being a standard phy. If the parent hardware
> is capable, it makes sense to scan for c22 devices before
> falling back to c45.
>
> As we want this to reflect the capabilities of the STA,
> lets add a field to the mii_bus structure to represent
> the capability. That way devices can opt into the extended
> scanning. Existing users should continue to default to c22
> only scanning as long as they are zero'ing the structure
> before use.
>
> Signed-off-by: Jeremy Linton <jeremy.lin...@arm.com>
> Signed-off-by: Calvin Johnson <calvin.john...@oss.nxp.com>
I know that we've hashed this out quite a bit already, but I would like
to point out that include/linux/mdio.h contains:
* struct mdio_if_info - Ethernet controller MDIO interface
* @mode_support: MDIO modes supported. If %MDIO_SUPPORTS_C22 is set then
* MII register access will be passed through with @devad =
* %MDIO_DEVAD_NONE. If %MDIO_EMULATE_C22 is set then access to
* commonly used clause 22 registers will be translated into
* clause 45 registers.
#define MDIO_SUPPORTS_C22 1
#define MDIO_SUPPORTS_C45 2
#define MDIO_EMULATE_C22 4
While this structure is not applicable to phylib or mii_bus, it may be
worth considering that there already exist definitions for identifying
the properties of the underlying bus.
> ---
>
> drivers/net/phy/mdio_bus.c | 17 +++++++++++++++--
> include/linux/phy.h | 7 +++++++
> 2 files changed, 22 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
> index 6ceee82b2839..e6c179b89907 100644
> --- a/drivers/net/phy/mdio_bus.c
> +++ b/drivers/net/phy/mdio_bus.c
> @@ -739,10 +739,23 @@ EXPORT_SYMBOL(mdiobus_free);
> */
> struct phy_device *mdiobus_scan(struct mii_bus *bus, int addr)
> {
> - struct phy_device *phydev;
> + struct phy_device *phydev = ERR_PTR(-ENODEV);
> int err;
>
> - phydev = get_phy_device(bus, addr, false);
> + switch (bus->probe_capabilities) {
> + case MDIOBUS_C22:
> + phydev = get_phy_device(bus, addr, false);
> + break;
> + case MDIOBUS_C45:
> + phydev = get_phy_device(bus, addr, true);
> + break;
> + case MDIOBUS_C22_C45:
> + phydev = get_phy_device(bus, addr, false);
> + if (IS_ERR(phydev))
> + phydev = get_phy_device(bus, addr, true);
> + break;
> + }
> +
> if (IS_ERR(phydev))
> return phydev;
>
> diff --git a/include/linux/phy.h b/include/linux/phy.h
> index 9248dd2ce4ca..50e5312b2304 100644
> --- a/include/linux/phy.h
> +++ b/include/linux/phy.h
> @@ -298,6 +298,13 @@ struct mii_bus {
> /* RESET GPIO descriptor pointer */
> struct gpio_desc *reset_gpiod;
>
> + /* bus capabilities, used for probing */
> + enum {
> + MDIOBUS_C22 = 0,
> + MDIOBUS_C45,
> + MDIOBUS_C22_C45,
> + } probe_capabilities;
I think it would be better to reserve "0" to mean that no capabilities
have been declared. We hae the situation where we have mii_bus that
exist which do support C45, but as they stand, probe_capabilities will
be zero, and with your definitions above, that means MDIOBUS_C22.
It seems this could lock in some potential issues later down the line
if we want to use this elsewhere.
--
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