linux-kernel - ata_tf_read

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Message-Id: <20090815.224843.240484147.anemo@mba.ocn.ne.jp>
Date:	Sat, 15 Aug 2009 22:48:43 +0900 (JST)
From:	Atsushi Nemoto <anemo@....ocn.ne.jp>
To:	Jeff Garzik <jgarzik@...ox.com>, Tejun Heo <htejun@...il.com>
Cc:	linux-ide@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: ata_tf_read_block() question

I have a question on CHS calculation in ata_tf_read_block().

The calculation in ata_tf_read_block() is:
	block = (cyl * dev->heads + head) * dev->sectors + sect;

but ata_build_rw_tf() does:
	track = (u32)block / dev->sectors;
	cyl   = track / dev->heads;
	head  = track % dev->heads;
	sect  = (u32)block % dev->sectors + 1;

It seems inconsistent.  The correct calculation is:
	block = (cyl * dev->heads + head) * dev->sectors + sect - 1;
isn't it?

I don't have any real problem.  Just noticed by code reading.
---
Atsushi Nemoto
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