On 20-09-26 07:44:57, Greg KH wrote:
> On Fri, Sep 25, 2020 at 07:01:59PM +0300, Petko Manolov wrote:
> > From: Petko Manolov <petko.manolov@xxxxxxxxxxxx>
> >
> > Move all control transfers to safer usb_control_msg_send/recv() API.
>
> This says _what_ the patch does, but we can see that from the diff. You
> should describe _why_ we are doing what we are doing, so that everyone
> understands the need for the change.
Didn't want to parrot the reason for usb_control_msg_send/recv() existence, but
i guess you're right. 5 years from now i would not remember anything. :)
> > static int set_register(pegasus_t *pegasus, __u16 indx, __u8 data)
> > {
> > - u8 *buf;
> > - int ret;
> > -
> > - buf = kmemdup(&data, 1, GFP_NOIO);
> > - if (!buf)
> > - return -ENOMEM;
> > -
> > - ret = usb_control_msg(pegasus->usb, usb_sndctrlpipe(pegasus->usb, 0),
> > - PEGASUS_REQ_SET_REG, PEGASUS_REQT_WRITE, data,
> > - indx, buf, 1, 1000);
> > - if (ret < 0)
> > - netif_dbg(pegasus, drv, pegasus->net,
> > - "%s returned %d\n", __func__, ret);
> > - kfree(buf);
> > - return ret;
> > + return usb_control_msg_send(pegasus->usb, 0, PEGASUS_REQ_SET_REG,
> > + PEGASUS_REQT_WRITE, data, indx, &data, 1,
> > + 1000, GFP_NOIO);
> > }
>
> Again, why isn't set_register() now rewritten to just be:
>
> static int set_register(pegasus_t *pegasus, __u16 indx, __u8 data)
> {
> return set_registers(pegasus, indx, 1, data);
> }
>
> Much easier to show that it's all converted properly :)
There's a catch - adm8511-based devices can only write to a single register via
specific control request. This request expects the register number in wIndex
and the value in wValue. A bit of a brain fart which is fixed in adm8515.
Admittedly, I could open code set_register() and avoid a kmemdup() call since in
this case 'data' is going to be NULL. However, set_register() isn't heavily
used, except for the setup phase, so i went for the prettier/simpler approach.
Which reminds me that i should put a comment explaining why is that.
cheers,
Petko
