netdev - Re: [PATCH 1/2] net: mdiobus: reset deassert delay

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Date:   Tue, 28 Jul 2020 09:32:03 -0300
From:   Fabio Estevam <festevam@...il.com>
To:     Bruno Thomsen <bruno.thomsen@...il.com>
Cc:     netdev <netdev@...r.kernel.org>, Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        Russell King - ARM Linux <linux@...linux.org.uk>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Lars Alex Pedersen <laa@...strup.com>,
        Bruno Thomsen <bth@...strup.com>
Subject: Re: [PATCH 1/2] net: mdiobus: reset deassert delay

Hi Bruno,

On Tue, Jul 28, 2020 at 6:02 AM Bruno Thomsen <bruno.thomsen@...il.com> wrote:
>
> The current reset logic only has a delay during assert.
> This reuses the delay value as deassert delay to ensure
> PHYs are ready for commands. Delays are typically needed
> when external hardware slows down reset release with a
> RC network. This solution does not need any new device
> tree bindings.
> It also improves handling of long delays (>20ms) by using
> the generic fsleep() for selecting appropriate delay
> function.

It seems that this patch should be split in two:

One that changes from udelay() to sleep()
and another one that adds the delay after the reset line is de-asserted.

>
> Signed-off-by: Bruno Thomsen <bruno.thomsen@...il.com>
> ---
>  drivers/net/phy/mdio_bus.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
> index 6ceee82b2839..84d5ab07fe16 100644
> --- a/drivers/net/phy/mdio_bus.c
> +++ b/drivers/net/phy/mdio_bus.c
> @@ -627,8 +627,9 @@ int __mdiobus_register(struct mii_bus *bus, struct module *owner)
>                 bus->reset_gpiod = gpiod;
>
>                 gpiod_set_value_cansleep(gpiod, 1);
> -               udelay(bus->reset_delay_us);
> +               fsleep(bus->reset_delay_us);
>                 gpiod_set_value_cansleep(gpiod, 0);
> +               fsleep(bus->reset_delay_us);

Shouldn't it use the value passed in the reset-deassert-us property instead?