Linux Input/HID development
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From: Joey Oravec <joravec@drewtech.com>
To: dtor@mail.ru
Cc: linux-input@vger.kernel.org
Subject: linux raw serio driver 32 byte maximum
Date: Tue, 30 Aug 2011 17:59:49 -0400	[thread overview]
Message-ID: <4E5D5D55.5060207@drewtech.com> (raw)

Dmitry -

In serio_raw.c function serio_raw_write() there's a check:

if (count > 32)
    count = 32;

which coerces any call to write a maximum of 32 bytes. Do you know why 
this limitation is in the code? Characters get written one-by-one to the 
tty layer so I don't understand why it's there.

I'm not sure which section of the manpage defines write for a serial 
port. In the ordinary case I expected this function to keep transmitting 
until complete or an error occurs. If O_NONBLOCK was specified then I 
might expect EAGAIN. Right now my calling code doesn't expect a 
successful partial write. Do you think this module is doing the right 
thing? Can you comment on what the caller must expect?

-joey

             reply	other threads:[~2011-08-30 22:06 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-08-30 21:59 Joey Oravec [this message]
2011-08-30 22:50 ` linux raw serio driver 32 byte maximum Dmitry Torokhov
2011-08-31  0:40   ` Joey Oravec

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