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

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Date:	Wed, 16 Oct 2013 07:10:03 +0000
From:	"Dorau, Lukasz" <lukasz.dorau@...el.com>
To:	Tejun Heo <tj@...nel.org>
CC:	"linux-ide@...r.kernel.org" <linux-ide@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 2] libahci: fix turning on LEDs in ahci_start_port()

On Tuesday, October 15, 2013 3:41 PM Tejun Heo <tj@...nel.org> wrote:
> 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.
> 
Thanks.

Lukasz

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