Hans-Christian Egtvedt wrote:

On Sun, 13 Dec 2009 20:49:37 -0800
Dmitry Torokhov [off-list ref] wrote:

quoted

Hi Martin,

On Sun, Dec 13, 2009 at 02:25:25PM +0100, Marjan Fojkar wrote:

quoted

From: Marjan Fojkar <redacted>

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? :)