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* RE: [PATCH] libata-sff: Reenable Port Multiplier after libata-sff remodeling.
@ 2010-09-01 16:33 Kalra Ashish-B00888
  0 siblings, 0 replies; 18+ messages in thread
From: Kalra Ashish-B00888 @ 2010-09-01 16:33 UTC (permalink / raw)
  To: Tejun Heo, Gwendal Grignou; +Cc: jeff, nicolas, linux-ide



Sent from my HTC

-----Original Message-----
From: Tejun Heo <tj@kernel.org>
Sent: 01 September 2010 1:52 PM
To: Gwendal Grignou <gwendal@google.com>
Cc: jeff@garzik.org <jeff@garzik.org>; nicolas@jungers.net <nicolas@jungers.net>; linux-ide@vger.kernel.org <linux-ide@vger.kernel.org>
Subject: Re: [PATCH] libata-sff: Reenable Port Multiplier after libata-sff remodeling.

Hello,

On 09/01/2010 01:17 AM, Gwendal Grignou wrote:
> On Tue, Aug 31, 2010 at 1:04 AM, Tejun Heo <tj@kernel.org> wrote:
>> On 08/30/2010 07:17 PM, Gwendal Grignou wrote:
>>> Keep track of the link on the which the current request is in progress.
>>> It allows support of links behind port multiplier.
>>>
>>> Not all libata-sff is PMP compliant. Code for native BMDMA controller
>>> does not take in accound PMP.
>>
>> Can you please elaborate a bit more on what broke and how this patch
>> fixes the problem?
> Before this patch, all libata-sff assumes the qc in progess is tied to
> ap->link, the host port link.
> That's fine as long as the controllers do not support port multiplier,
> which is the case of all controller inheriting ata_sff_port_ops except
> some controllers managed by sata_mv.
> Also, before the libata-ssf reorg, it did not matter, qc was given the
> sff task directly.
> 
> However, sata_mv supports port multiplier and use part of libata-sff
> to hanlde PIO commands to disks. qc sent to disk behind port
> multiplier are tight to one of element pmp_link array.
> Therefore, the part of libata-sff sata_mv exercises must be retrieve
> qc from the provided link instead of ap->link.

Heh, I meant to elaborate in the patch description. :-) Sorry about
not being clearer.

>> It would also be useful to have WARN/BUG_ON() to make sure no two
>> links try to use pio_task at the same time.  ie. Set
>> ap->sff_pio_task_link here and clear it with NULL when done and make
>> sure it's NULL before setting it.
>
> Add some WARN/BUG. I set link to NULL very early, I believe it is
> cleaner than setting it in hsm_move() itself.
> Patch after the break.

Thanks.

-- 
tejun
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^ permalink raw reply	[flat|nested] 18+ messages in thread

end of thread, other threads:[~2010-09-01 16:35 UTC | newest]

Thread overview: 18+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
     [not found] <4C702070.5020809@jungers.net>
2010-08-21 19:13 ` possible esata regression in 2.6.35 Mark Lord
2010-08-21 19:59   ` Nicolas Jungers
2010-08-22 19:54 ` Jeff Garzik
2010-08-22 19:57   ` Jeff Garzik
2010-08-27  8:19     ` Gwendal Grignou
     [not found]       ` <AANLkTi=deJbndavPJmFzEoy6kZQX8LdoAdE+QQN5if0=@mail.gmail.com>
2010-08-27 22:56         ` Gwendal Grignou
2010-08-29  0:31           ` [PATCH] libata-sff: Reenable Port Multiplier after libata-sff remodeling Gwendal Grignou
2010-08-29  9:05             ` Tejun Heo
2010-08-30 17:17               ` Gwendal Grignou
2010-08-31  8:04                 ` Tejun Heo
2010-08-31 23:17                   ` Gwendal Grignou
2010-09-01  8:21                     ` Tejun Heo
2010-08-31 23:20                   ` Gwendal Grignou
2010-08-31 23:32                     ` Jeff Garzik
2010-09-01  5:57                       ` Gwendal Grignou
2010-08-30 17:19               ` Gwendal Grignou
2010-08-29  0:40           ` possible esata regression in 2.6.35 Gwendal Grignou
2010-09-01 16:33 [PATCH] libata-sff: Reenable Port Multiplier after libata-sff remodeling Kalra Ashish-B00888

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