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From: Tejun Heo <htejun@gmail.com>
To: Jeff Garzik <jeff@garzik.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>, Mark Lord <liml@rtr.ca>,
	linux-ide@vger.kernel.org
Subject: Re: Polling (was Re: [PATCHSET 2/2] implement PMP support, take 6)
Date: Tue, 02 Oct 2007 09:11:30 +0900	[thread overview]
Message-ID: <47018CB2.8020008@gmail.com> (raw)
In-Reply-To: <4700F6BE.3060904@garzik.org>

Jeff Garzik wrote:
> Polling PMP 2.6.24 is completely unacceptable.  It screws the 2.6.24 SAS
> driver releases out of PMP.

Not merging PMP has about the same effect for SAS, right?

> I pulled your last PMP patchset, and will now endeavor to fix the API
> prior to 2.6.24 merge window opening.

I have a preliminary patch.  The patch is pretty simple too.  I'll
submit after some testing but I'm not sure whether doing this right
before the merge window is a good idea.  I'd prefer not to support PMP
on SAS for 2.6.24.

> Linux high level message-submit / message-complete APIs should never
> _require_ polling, even if its 100% polling under the hood.  There are
> far too many cases in the field where you don't have direct access to
> hardware registers to poll.  Or such polling would interfere with the
> operation of other ports.  Or any of a myriad of other reasons.

I don't think that's true for actual ATA controllers but, for SAS,
probably true.  Is the frozen reset mechanism a headache too for SAS?

Thanks.

-- 
tejun

  reply	other threads:[~2007-10-02  0:13 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-09-23  4:19 [PATCHSET 2/2] implement PMP support, take 6 Tejun Heo
2007-09-23  4:19 ` [PATCH 01/10] libata-pmp: update ata_eh_reset() for PMP Tejun Heo
2007-09-23  4:19 ` [PATCH 03/10] libata-pmp: hook PMP support and enable it Tejun Heo
2007-09-23  4:19 ` [PATCH 07/10] sata_sil24: implement PORT_RST Tejun Heo
2007-09-23  4:19 ` [PATCH 08/10] ahci: implement PMP support Tejun Heo
2007-09-23  4:19 ` [PATCH 02/10] libata-pmp: implement Port Multiplier support Tejun Heo
2007-09-23  4:19 ` [PATCH 04/10] libata-pmp: extend ACPI support to cover PMP Tejun Heo
2007-09-23  4:19 ` [PATCH 06/10] sata_sil24: implement PMP support Tejun Heo
2007-09-23  4:19 ` [PATCH 05/10] libata-pmp: implement qc_defer for command switching " Tejun Heo
2007-09-23  4:19 ` [PATCH 10/10] ahci: implement AHCI_HFLAG_NO_PMP Tejun Heo
2007-09-23  4:19 ` [PATCH 09/10] ahci: move host flags over to pi.private_data Tejun Heo
2007-09-26  2:09 ` Polling (was Re: [PATCHSET 2/2] implement PMP support, take 6) Jeff Garzik
2007-09-26  2:12   ` Jeff Garzik
2007-09-26  8:41   ` Tejun Heo
2007-09-28 12:10     ` Tejun Heo
2007-09-28 13:54     ` Jeff Garzik
2007-09-28 14:18       ` Tejun Heo
2007-09-28 14:57         ` Alan Cox
2007-09-28 15:20           ` Jeff Garzik
2007-09-28 15:43             ` Alan Cox
2007-09-28 15:40               ` Jeff Garzik
2007-09-28 20:00                 ` Mark Lord
2007-09-29  1:49                   ` Jeff Garzik
2007-09-29  3:29                   ` Jeff Garzik
2007-09-29  4:58                     ` Andrew Morton
2007-09-29  5:09                       ` Jeff Garzik
2007-09-29 16:51                     ` Greg Freemyer
2007-09-29 20:56                     ` Alan Cox
2007-10-01 12:28                       ` Jeff Garzik
2007-09-28 15:22         ` Jeff Garzik
2007-09-28 16:48           ` Tejun Heo
2007-09-28 20:02             ` Mark Lord
2007-09-28 20:25               ` Bartlomiej Zolnierkiewicz
2007-09-28 21:03               ` Alan Cox
2007-09-29  1:43                 ` Jeff Garzik
2007-09-29  5:24                   ` Tejun Heo
2007-10-01 13:31                     ` Jeff Garzik
2007-10-02  0:11                       ` Tejun Heo [this message]
2007-10-02 14:25                       ` Alan Cox
2007-10-02 14:30                         ` Jeff Garzik
2007-09-29 12:32                   ` Mark Lord
2007-10-01 12:38                     ` Jeff Garzik
2007-10-02  0:12                       ` Tejun Heo
2007-10-02 12:56                         ` Jeff Garzik
2007-10-02 13:06                           ` Mark Lord
2007-10-02 13:30                             ` Jeff Garzik
2007-10-06 22:02                               ` Tejun Heo
2007-10-09  2:09                                 ` Jeff Garzik
2007-10-09  6:54                                   ` Tejun Heo
2007-09-28 14:20   ` Mark Lord
2007-09-28 15:36     ` Jeff Garzik
2007-09-28 15:55       ` Alan Cox

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