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    SubjectRe: [PATCH] net: phy: at803x: don't depend on GPIOLIB
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    On 22/03/2016 20:42, Uwe Kleine-König wrote:

    > Preconditions:
    > - Some of the devices a given driver handles have a reset line and
    > others don't.
    > - A non-empty subset (maybe all) of the devices that have a reset line
    > require that this reset line is used.
    >
    > Then the way to handle this in the driver should be done as follows:
    >
    > unless reset_handling_not_necessary():
    > gpio = gpiod_get_optional("reset")
    > if IS_ERR(gpio):
    > return PTR_ERR(gpio)
    >
    > Checking for -ENOSYS or GPIOLIB=n is not allowed because the device
    > you're currently handling might need the GPIO, so you must not continue
    > without the ability to control the line.
    >
    > So the options you have (as you have a phy that doesn't need the reset
    > handling):
    >
    > - enable GPIOLIB (either in your .config or introduce a Kconfig
    > dependency)
    > - improve reset_handling_not_necessary() to return true for your case
    >
    > There is nothing else.

    Here are some numbers for GPIOLIB, on an ARM build:

    text data bss dec hex filename
    1830 0 0 1830 726 devres.o
    627 0 0 627 273 gpiolib-legacy.o
    11018 40 4 11062 2b36 gpiolib.o
    1598 0 0 1598 63e gpiolib-of.o
    --------------------------------------------------------
    15073 40 4 15117 3b0d built-in.o

    So ~15 kilobytes.


    By the way, since the "reset-by-GPIO" solution is used only for
    the Atheros 8030, would it be possible to make the
    devm_gpiod_get_optional conditional on ATH8030_PHY_ID?

    I'm thinking of something along these lines, for illustration:

    diff --git a/drivers/net/phy/at803x.c b/drivers/net/phy/at803x.c
    index 2d020a3ec0b5..576e7873e049 100644
    --- a/drivers/net/phy/at803x.c
    +++ b/drivers/net/phy/at803x.c
    @@ -198,12 +198,16 @@ static int at803x_probe(struct phy_device *phydev)
    if (!priv)
    return -ENOMEM;

    + if (phydev->drv->phy_id != ATH8030_PHY_ID)
    + goto no_gpio;
    +
    gpiod_reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
    if (IS_ERR(gpiod_reset))
    return PTR_ERR(gpiod_reset);

    priv->gpiod_reset = gpiod_reset;

    +no_gpio:
    phydev->priv = priv;

    return 0;

    Regards.

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