On Mon, Apr 27, 2015 at 09:13:35PM +0900, Chanwoo Choi wrote:
> This patch modify the device name as extcon[X] for sysfs by using the 'extcon'
> prefix word instead of separate device name. On user-space aspect, user would
> find the some extcon drvier with extcon[X] pattern. So, this patch modify the
> device name as following:
> - /sys/class/extcon/[device name] -> /sys/class/extcon/extcon[X]
>
> Signed-off-by: Chanwoo Choi <cw00.c...@samsung.com>
> ---
> drivers/extcon/extcon.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/extcon/extcon.c b/drivers/extcon/extcon.c
> index 4c9f165..1a93229 100644
> --- a/drivers/extcon/extcon.c
> +++ b/drivers/extcon/extcon.c
> @@ -163,7 +163,7 @@ static ssize_t name_show(struct device *dev, struct
> device_attribute *attr,
> return ret;
> }
>
> - return sprintf(buf, "%s\n", dev_name(&edev->dev));
> + return sprintf(buf, "%s\n", edev->name);
> }
> static DEVICE_ATTR_RO(name);
>
> @@ -701,6 +701,7 @@ EXPORT_SYMBOL_GPL(devm_extcon_dev_free);
> int extcon_dev_register(struct extcon_dev *edev)
> {
> int ret, index = 0;
> + static atomic_t edev_no = ATOMIC_INIT(-1);
>
> if (!extcon_class) {
> ret = create_extcon_class();
> @@ -725,13 +726,14 @@ int extcon_dev_register(struct extcon_dev *edev)
> edev->dev.class = extcon_class;
> edev->dev.release = extcon_dev_release;
>
> - edev->name = edev->name ? edev->name : dev_name(edev->dev.parent);
> + edev->name = dev_name(edev->dev.parent);
> if (IS_ERR_OR_NULL(edev->name)) {
> dev_err(&edev->dev,
> "extcon device name is null\n");
> return -EINVAL;
> }
> - dev_set_name(&edev->dev, "%s", edev->name);
> + dev_set_name(&edev->dev, "extcon%lu",
> + (unsigned long)atomic_inc_return(&edev_no));
>
> if (edev->max_supported) {
> char buf[10];
> --
> 1.8.5.5
>
I am not quite sure I see the advantage of this. Why is naming
the node extcon[X] better than the old system? Seems like the
older more descriptive names are better on the face of it, unless
there is some problem with them I am missing.
It also looks problematic, it changes the ABI for the Arizona
extcon driver for a start, admittedly there arn't many users for
the extcon driver at the moment but still is far from ideal to
break the ABI. Secondly, the order of the extcon[X]'s will not be
guaranteed, add some new hardware to the system probe order
changes and now what was extcon0 is extcon1. So it somewhat
complicates the user-space code as it now has to work out if the
device is the one it wants whereas before it could just hard-code
the name.
Thanks,
Charles
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