Re: [PATCH v4] net: mdiobus: Add a function to deassert reset

[Yan Wang]

On 5/11/2023 8:40 PM, Simon Horman wrote:
> On Thu, May 11, 2023 at 02:59:09PM +0800, Yan Wang wrote:
> > It is possible to mount multiple sub-devices on the mido bus.
> > The hardware power-on does not necessarily reset these devices.
> > The device may be in an uncertain state, causing the device's ID
> > to not be scanned.
> >
> > So,before adding a reset to the scan, make sure the device is in
> > normal working mode.
> >
> > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > Link: https://lore.kernel.org/oe-kbuild-all/202305101702.4xW6vT72-lkp@xxxxxxxxx/
> > Signed-off-by: Yan Wang <rk.code@xxxxxxxxxxx>
> ...
>
> > diff --git a/drivers/net/mdio/fwnode_mdio.c b/drivers/net/mdio/fwnode_mdio.c
> > index 1183ef5e203e..9d7df6393059 100644
> > --- a/drivers/net/mdio/fwnode_mdio.c
> > +++ b/drivers/net/mdio/fwnode_mdio.c
> > @@ -11,6 +11,7 @@
> >   #include <linux/of.h>
> >   #include <linux/phy.h>
> >   #include <linux/pse-pd/pse.h>
> > +#include <linux/gpio/consumer.h>
> >   
> >   MODULE_AUTHOR("Calvin Johnson <calvin.johnson@xxxxxxxxxxx>");
> >   MODULE_LICENSE("GPL");
> > @@ -57,6 +58,35 @@ fwnode_find_mii_timestamper(struct fwnode_handle *fwnode)
> >   	return register_mii_timestamper(arg.np, arg.args[0]);
> >   }
> >   
> > +static void fwnode_mdiobus_pre_enable_phy(struct fwnode_handle *fwnode)
> > +{
> > +	struct gpio_desc *reset;
> > +	unsigned int reset_assert_delay;
> > +	unsigned int reset_deassert_delay;
> nit: Please arrange local variables for networking code in reverse xmas
>       tree order - longest line to shortest.
>
> > +
> > +	reset = fwnode_gpiod_get_index(fwnode, "reset", 0, GPIOD_OUT_LOW, NULL);
> > +	if (IS_ERR(reset)) {
> > +		if (PTR_ERR(reset) == -EPROBE_DEFER)
> > +			pr_debug("%pOFn: %s: GPIOs not yet available, retry later\n",
> > +				 to_of_node(fwnode), __func__);
> > +		else
> > +			pr_err("%pOFn: %s: Can't get reset line property\n",
> > +			       to_of_node(fwnode), __func__);
> > +
> > +		return;
> > +	}
> > +	fwnode_property_read_u32(fwnode, "reset-assert-us",
> > +				 &reset_assert_delay);
> > +	fwnode_property_read_u32(fwnode, "reset-deassert-us",
> > +				 &reset_deassert_delay);
> Does the return value of fwnode_property_read_u32() need to be
> checked for errors?
>
> > +	gpiod_set_value_cansleep(reset, 1);
> > +	fsleep(reset_assert_delay);
> > +	gpiod_set_value_cansleep(reset, 0);
> > +	fsleep(reset_deassert_delay);
> > +	/*Release phy's reset line, mdiobus_register_gpiod() need to request it*/
> nit:
>
> 	/* Release phy's reset line, mdiobus_register_gpiod() needs to
> 	 * request it.
> 	 */

Thank you for your suggestion.

Best Regards
> > +	gpiod_put(reset);
> > +}
> > +
> >   int fwnode_mdiobus_phy_device_register(struct mii_bus *mdio,
> >   				       struct phy_device *phy,
> >   				       struct fwnode_handle *child, u32 addr)
> > @@ -119,6 +149,8 @@ int fwnode_mdiobus_register_phy(struct mii_bus *bus,
> >   	u32 phy_id;
> >   	int rc;
> >   
> > +	fwnode_mdiobus_pre_enable_phy(child);
> > +
> >   	psec = fwnode_find_pse_control(child);
> >   	if (IS_ERR(psec))
> >   		return PTR_ERR(psec);
> > --
> > 2.17.1