linux-kernel - Re: [PATCH v4 1/5] Implement an ioctl to support the USMTMC-USB488 READ_STATUS

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Message-ID: <20151118081247.GA1776@slacky>
Date:	Wed, 18 Nov 2015 09:12:47 +0100
From:	Dave Penkler <dpenkler@...il.com>
To:	Andy Shevchenko <andy.shevchenko@...il.com>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	peter.chen@...escale.com, teuniz@...il.com,
	USB <linux-usb@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 1/5] Implement an ioctl to support the USMTMC-USB488
 READ_STATUS_BYTE operation.

Hi Andy,
On Sun, Nov 15, 2015 at 10:04:10PM +0200, Andy Shevchenko wrote:
> On Sun, Nov 15, 2015 at 8:39 PM, Dave Penkler <dpenkler@...il.com> wrote:

snip

> > +
> 
> Redundant empty line.
> 

ok

> 
> > +               data->iin_bTag = 2;
> 
> Hmm??? Why 2?
> A-ha, below I found a comment. Something might be good to have here as well.
> 

Added comment

> > +
> 
> Redundant empty line.
> 

ok

> > +
> > +               if (data->iin_buffer[0] & 0x80) {
> > +                       /* check for valid STB notification */
> > +                       if ((data->iin_buffer[0] & 0x7f) > 1) {
> 
> It's the same as
>      if (data->iin_buffer[0] & 0x7e) {
> 

Yes but when reading the spec and the code it is more obvious that here
we are testing for the value in bits D6..D0 to be a valid iin_bTag return. 
(See Table 7 in the USBTMC-USB488 spec.)

> > +               dev_dbg(&data->intf->dev,
> > +                       "%s - urb terminated, status: %d\n",
> 
> I heard that dynamic debug adds function name.
> 
> > +                       __func__, status);

I checked in device.h and could not find any trace of it. I'm on 4.4.0-rc1.

> > +static void usbtmc_free_int(struct usbtmc_device_data *data)
> > +{
> > +       if (data->iin_ep_present) {
> > +               if (data->iin_urb) {
> 
> Why not
> 
> if (!data->iin_ep_present || !data->iin_urb)
>   return;
> 
> ?
> 

OK

Thanks,
-Dave
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