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Date: Wed, 7 Nov 2007 13:09:40 +0000
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Paul Mundt <lethal@linux-sh.org>
Cc: Jeff Garzik <jeff@garzik.org>, Andrew Morton <akpm@linux-foundation.org>,
       linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org,
       linuxsh-dev@lists.sourceforge.net
Subject: Re: [PATCH 1/2] libata: Support PIO polling-only hosts.
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On Wed, 7 Nov 2007 17:10:52 +0900
Paul Mundt <lethal@linux-sh.org> wrote:

> By default ata_host_activate() expects a valid IRQ in order to
> successfully register the host. This patch enables a special case
> for registering polling-only hosts that either don't have IRQs
> or have buggy IRQ generation (either in terms of handling or
> sensing), which otherwise work fine.
> 
> Hosts that want to use polling mode can simply set ATA_FLAG_PIO_POLLING
> and pass in a NULL IRQ handler or invalid (< 0) IRQ.

NAK

Zero is "no IRQ", please use that for polling not "< 0"

> + *	A NULL @irq_handler or invalid IRQ skips the IRQ registration
> + *	and expects the host to have set polling mode on the port.
> + *

There is no need to llow NULL irq_handler as a different case here. Any
caller can provide (NULL, 0). If anything you might want to warn if they
provide IRQ 0, and a handler