linux-kernel - Re: [PATCH v5 1/5] Implement an ioctl to support the USMTMC-USB488 READ_STATUS

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Message-ID: <CAHp75VdSk7ZM77UznAoGM-nHuQfgvO+dawyiD1ShV6HofoYXrA@mail.gmail.com>
Date:	Sat, 28 Nov 2015 16:57:47 +0200
From:	Andy Shevchenko <andy.shevchenko@...il.com>
To:	Dave Penkler <dpenkler@...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 v5 1/5] Implement an ioctl to support the USMTMC-USB488
 READ_STATUS_BYTE operation.

On Sat, Nov 28, 2015 at 1:55 PM, Dave Penkler <dpenkler@...il.com> wrote:
> On Wed, Nov 25, 2015 at 10:38:39PM +0200, Andy Shevchenko wrote:
>> On Wed, Nov 25, 2015 at 11:18 AM, Dave Penkler <dpenkler@...il.com> wrote:
>> > On Sun, Nov 22, 2015 at 12:32:41PM +0200, Andy Shevchenko wrote:
>> >> On Sun, Nov 22, 2015 at 11:19 AM, Dave Penkler <dpenkler@...il.com> wrote:
>> >> > On Wed, Nov 18, 2015 at 11:55:27AM +0200, Andy Shevchenko wrote:
>> >> >> On Wed, Nov 18, 2015 at 10:37 AM, Dave Penkler <dpenkler@...il.com> wrote:

Thank you for an update!

>> >> >> > +       switch (status) {
>> >> >> > +       case 0: /* SUCCESS */
>> >> >> > +               if (data->iin_buffer[0] & 0x80) {
>> >> >> > +                       /* check for valid STB notification */
>> >> >> > +                       if ((data->iin_buffer[0] & 0x7f) > 1) {

How can I miss that there are two conditionals in a sequence and
moreover for the same data?!
That might explain the optimization done by compiler.

So, could it be transformed to simple one condition
   if (data->iin_buffer[0] > 0x81 /* 129 */) {
?

-- 
With Best Regards,
Andy Shevchenko
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