linux-kernel - Re: [PATCH 2] libahci: fix turning on LEDs in ahci_start

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Message-ID: <20131015134058.GF3141@htj.dyndns.org>
Date:	Tue, 15 Oct 2013 09:40:58 -0400
From:	Tejun Heo <tj@...nel.org>
To:	Lukasz Dorau <lukasz.dorau@...el.com>
Cc:	linux-ide@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2] libahci: fix turning on LEDs in ahci_start_port()

On Mon, Oct 14, 2013 at 06:18:53PM +0200, Lukasz Dorau wrote:
> If EM Transmit bit is busy during init ata_msleep() is called.
> It is wrong - msleep() should be used instead of ata_msleep(),
> because if EM Transmit bit is busy for one port, it will be busy
> for all other ports too, so using ata_msleep() causes wasting
> tries for another ports.
> 
> The most common scenario looks like that now
> (six ports try to transmit a LED meaasege):
> - port #0 tries for the 1st time and succeeds
> - ports #1-5 try for the 1st time and sleeps
> - port #1 tries for the 2nd time and succeeds
> - ports #2-5 try for the 2nd time and sleeps
> - port #2 tries for the 3rd time and succeeds
> - ports #3-5 try for the 3rd time and sleeps
> - port #3 tries for the 4th time and succeeds
> - ports #4-5 try for the 4th time and sleeps
> - port #4 tries for the 5th time and succeeds
> - port #5 tries for the 5th time and sleeps
> At this moment port #5 wasted all its five tries and failed to initialize.
> Because there are only 5 (EM_MAX_RETRY) tries available usually only five ports
> succeed to initialize. The sixth port and next ones usually will fail.
> 
> If msleep() is used instead of ata_msleep() the first port succeeds to initialize
> in the first try and next ones usually succeed to initialize in the second try.
> 
> Signed-off-by: Lukasz Dorau <lukasz.dorau@...el.com>

Applied to libata/for-3.12-fixes with minor updates.

Thanks.

-- 
tejun
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