On Sat, 2016-12-03 at 10:04 +0100, Greg KH wrote:
> 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.
Good point, this actually started out as the front end interface and was
later demoted to debug only. I'll move it to debugfs.
>
> thanks,
>
> greg k-h
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