Re: [PATCH] AT32AP700X PS/2 controller (PSIF): remove msleep call from atomic context

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

On Sat, Dec 19, 2009 at 12:57:48PM +0100, Marjan Fojkar wrote:
> Hans-Christian Egtvedt wrote:
> > On Sun, 13 Dec 2009 20:49:37 -0800
> > Dmitry Torokhov <dmitry.torokhov@gmail.com> wrote:
> > 
> >> Hi Martin,
> >>
> >> On Sun, Dec 13, 2009 at 02:25:25PM +0100, Marjan Fojkar wrote:
> >>> From: Marjan Fojkar <marjan@pajkc.eu>
> >>>
> >>> The patch removes msleep call from atomic context. To achieve that, the driver
> >>> PSIF leaves atomic context before the call in order to enable interrupts to be
> >>> performed safely. When the call is done, the driver jumps back to atomic context.
> >>>
> >> Yes, msleep is not allowed in atomic context, however serio's write()
> >> method is supposed to be callable from atomic context so msleep is not
> >> available there period. I scanned the datasheet quickly and did not see
> >> any restriction on the frequency of reading status register so I think
> >> we should do what i8042 driver does - udelay(50).
> >>
> > 
> > Sure udelay(50) will work fine, you can poll the registers as fast as
> > you would like. Only disadvantage with udelay is that it will block all
> > other threads. But I would guess that most of the times a character
> > should be sent to the peripheral, the hardware will be ready since the
> > speed is quite low bandwidth.
> > 
> 
> So, the final conclusion is udelay(50), I presume? :)
> 

Yep, it is upstream now.

-- 
Dmitry