On Fri, Dec 02, 2016 at 10:37:01PM -0800, Todd Brandt wrote:
> Add debug support for experimenting with USB timing delay
> values on the fly. This provides a debug interface through
> /sys/kernel/usb where a user can tweak the values. The code
> enforces the spec minimums so that a user can't set them
> too low.
>
> Signed-off-by: Todd Brandt <todd.e.brandt@xxxxxxxxxxxxxxx>
> ---
> drivers/usb/core/hub.c | 100 +++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 100 insertions(+)
>
> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index 43242e3..6dea6a7 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -5265,8 +5265,98 @@ static struct usb_driver hub_driver = {
> .supports_autosuspend = 1,
> };
>
> +static ssize_t tdrsmdn_show(struct kobject *kobj,
> + struct kobj_attribute *attr, char *buf)
> +{
> + return sprintf(buf, "%d\n", usb_timing.tdrsmdn);
> +}
> +
> +static ssize_t tdrsmdn_store(struct kobject *kobj,
> + struct kobj_attribute *attr, const char *buf, size_t count)
> +{
> + int ret, val;
> +
> + ret = kstrtoint(buf, 10, &val);
> + if (ret < 0)
> + return ret;
> +
> + if (val < 20)
> + usb_timing.tdrsmdn = 20;
> + else
> + usb_timing.tdrsmdn = val;
> +
> + return count;
> +}
> +
> +static ssize_t trsmrcy_show(struct kobject *kobj,
> + struct kobj_attribute *attr, char *buf)
> +{
> + return sprintf(buf, "%d\n", usb_timing.trsmrcy);
> +}
> +
> +static ssize_t trsmrcy_store(struct kobject *kobj,
> + struct kobj_attribute *attr, const char *buf, size_t count)
> +{
> + int ret, val;
> +
> + ret = kstrtoint(buf, 10, &val);
> + if (ret < 0)
> + return ret;
> +
> + if (val < 10)
> + usb_timing.trsmrcy = 10;
> + else
> + usb_timing.trsmrcy = val;
> +
> + return count;
> +}
> +
> +static ssize_t trstrcy_show(struct kobject *kobj,
> + struct kobj_attribute *attr, char *buf)
> +{
> + return sprintf(buf, "%d\n", usb_timing.trstrcy);
> +}
> +
> +static ssize_t trstrcy_store(struct kobject *kobj,
> + struct kobj_attribute *attr, const char *buf, size_t count)
> +{
> + int ret, val;
> +
> + ret = kstrtoint(buf, 10, &val);
> + if (ret < 0)
> + return ret;
> +
> + if (val < 0)
> + usb_timing.trstrcy = 0;
> + else
> + usb_timing.trstrcy = val;
> +
> + return count;
> +}
> +
> +static struct kobj_attribute tdrsmdn_attr =
> + __ATTR(tdrsmdn, 0664, tdrsmdn_show, tdrsmdn_store);
> +static struct kobj_attribute trsmrcy_attr =
> + __ATTR(trsmrcy, 0664, trsmrcy_show, trsmrcy_store);
> +static struct kobj_attribute trstrcy_attr =
> + __ATTR(trstrcy, 0664, trstrcy_show, trstrcy_store);
__ATTR_RW() please.
> +
> +static struct attribute *attrs[] = {
> + &tdrsmdn_attr.attr,
> + &trsmrcy_attr.attr,
> + &trstrcy_attr.attr,
> + NULL
> +};
> +
> +static struct attribute_group attr_group = {
> + .attrs = attrs,
> +};
ATTRIBUTE_GROUP()?
> +
> int usb_hub_init(void)
> {
> + int retval;
> + struct kobject *usb_kobj;
> +
> if (usb_register(&hub_driver) < 0) {
> printk(KERN_ERR "%s: can't register hub driver\n",
> usbcore_name);
> @@ -5279,6 +5369,16 @@ int usb_hub_init(void)
> usb_timing.trstrcy = USB_TIMING_TRSTRCY_MIN;
> }
>
> + usb_kobj = kobject_create_and_add("usb", kernel_kobj);
> + if (!usb_kobj)
> + return -ENOMEM;
> +
> + retval = sysfs_create_group(usb_kobj, &attr_group);
> + if (retval) {
> + kobject_put(usb_kobj);
> + return retval;
> + }
Ick. Why not use debugfs instead please? Don't create random sysfs
files without documenting them in Documentation/ABI/
And for stuff like this, you don't want sysfs files, they should be in
debugfs, as that's what it is there for.
thanks,
greg k-h
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