Re: [PATCH] net: phy: at803x: don't depend on GPIOLIB

From: Sergei Shtylyov
Date: Wed Mar 23 2016 - 06:39:45 EST


On 3/23/2016 1:17 PM, Mason wrote:

- 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

- enable GPIOLIB (either in your .config or introduce a Kconfig
- 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);

We shouldn't call _optional() then, should we?

if (IS_ERR(gpiod_reset))
return PTR_ERR(gpiod_reset);

priv->gpiod_reset = gpiod_reset;

phydev->priv = priv;

return 0;


MBR, Sergei