On Mon, Sep 16, 2013 at 03:52:18PM +0000, KY Srinivasan wrote:
>
>
> > -----Original Message-----
> > From: Dmitry Torokhov [mailto:dmitry.torok...@gmail.com]
> > Sent: Monday, September 16, 2013 8:20 AM
> > To: KY Srinivasan
> > Cc: gre...@linuxfoundation.org; linux-kernel@vger.kernel.org;
> > de...@linuxdriverproject.org; linux-in...@vger.kernel.org; vojt...@suse.cz;
> > o...@aepfle.de; a...@canonical.com; jasow...@redhat.com
> > Subject: Re: [PATCH 1/1] Drivers: input: serio: New driver to support
> > Hyper-V
> > synthetic keyboard
> >
> > Hi K. Y.
> >
> > On Sun, Sep 15, 2013 at 10:28:54PM -0700, K. Y. Srinivasan wrote:
> > > Add a new driver to support synthetic keyboard. On the next generation
> > > Hyper-V guest firmware, many legacy devices will not be emulated and this
> > > driver will be required.
> > >
> > > I would like to thank Vojtech Pavlik <vojt...@suse.cz> for helping me
> > > with the
> > > details of the AT keyboard driver.
> > >
> >
> > In addition to what Dan said:
> >
> > > +
> > > +struct synth_kbd_protocol_response {
> > > + struct synth_kbd_msg_hdr header;
> > > + u32 accepted:1;
> > > + u32 reserved:31;
> > > +};
> >
> > Use of bitfields for on the wire structures makes me uneasy. I know that
> > currently you only going to run LE on LE, but still, maybe using
> > explicit shifts and masks would be better,
>
> This definition of the data structure is defined by the host. I will see what
> I
> can do here.
You do not really need to change protocol, you just sat that accepted is
the bit 0 of the word and define endianness (LE in your case). Then you
do:
struct synth_kbd_protocol_response {
struct synth_kbd_msg_hdr header;
__le32 status;
}
#define KBD_PROTOCOL_ACCEPTED BIT(0)
...
status = _le32_to_cpu(response->status);
accepted = status & KBD_PROTOCOL_ACCEPTED;
Thanks.
--
Dmitry
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