From: Roger Luethi <rl@hellgate.ch>
To: Pawan Deepika <pawan_deepika@yahoo.com>
Cc: linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [linux 2.4.18] via-rhine.c
Date: Tue, 20 May 2003 15:44:00 +0200 [thread overview]
Message-ID: <20030520134400.GB25041@k3.hellgate.ch> (raw)
In-Reply-To: <20030519194317.20999.qmail@web41606.mail.yahoo.com>
You should ask this kind of questions on the kernelnewbies list.
On Mon, 19 May 2003 12:43:17 -0700, Pawan Deepika wrote:
> through the source code in via-rhine.c. What I
> understand till now is that in Memory-mapped devices,
> I/O operation is performed using
> read(b/w/l)/write(b/w/l) functions while in IO mapped
> devices it is done using in/out(b/w/l). Am I right?
What you do with inb etc. is called PIO (Programmed I/O).
> But in via-rhine.c I notice use of inb and outb even
> in memory mapped case(code is shown below)
>
> ------------------------------------------------------
> #ifdef USE_MEM
> 530 static void __devinit enable_mmio(long ioaddr, int
> chip_id)
> 531 {
It does exactly what the function name says: it uses PIO to flip a bit in
some register to enable MMIO, which is just a different (and better) way to
transfer the data.
Roger
prev parent reply other threads:[~2003-05-20 13:31 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-05-19 19:43 [linux 2.4.18] via-rhine.c Pawan Deepika
2003-05-20 13:44 ` Roger Luethi [this message]
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