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From: Alexander Sabourenkov <screwdriver@lxnt.info>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: linux-ide@vger.kernel.org, Tejun Heo <htejun@gmail.com>,
	MisterE <MisterE2002@zonnet.nl>,
	benh@kernel.crashing.org, jgarzik@pobox.com, jeff@garzik.org
Subject: Re: [PATCH-RFC] Promise TX4 implement hw-bug workaround
Date: Sat, 27 Oct 2007 22:18:44 +0400	[thread overview]
Message-ID: <47238104.4000601@lxnt.info> (raw)
In-Reply-To: <20071027190916.5687fcaa@the-village.bc.nu>

Alan Cox wrote:
>> I can't think of a way to avoid second pass over scatterlist without
>> duplicating code (ata_qc_prep() and ata_fill_sg() from libata-core.c).
> 
> This appears to be incomplete:
> 

[...]

> 
> What guarantees you have enough PRD entries to do this without changing
> the limit in the structures ?
> 
> Otherwise looks good

PRD entries count is 256
include/linux/ata.h:
	ATA_MAX_PRD		= 256,
	ATA_PRD_TBL_SZ          = (ATA_MAX_PRD * ATA_PRD_SZ),

drivers/ata/libata-core.c:
 ap->prd = dmam_alloc_coherent(dev, ATA_PRD_TBL_SZ, &ap->prd_dma,

sata_promise Scsi_Host declares support for half of that:

include/linux/libata.h:
LIBATA_MAX_PRD		= ATA_MAX_PRD / 2,

drivers/ata/sata_promise.c
    .sg_tablesize           = LIBATA_MAX_PRD,


PS: Vendor code has this limit at 32.

-- 

./lxnt

  reply	other threads:[~2007-10-27 18:28 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-10-03  7:26 Re[2]: Sata Sil3512 bug? Mikael Pettersson
2007-10-03  8:31 ` Alexander Sabourenkov
2007-10-03 14:45   ` Re[2]: " MisterE
2007-10-03 14:50     ` Alan Cox
2007-10-14 12:07   ` Re[2]: " MisterE
2007-10-15  8:44     ` Alexander Sabourenkov
2007-10-17 12:39   ` Re[2]: Sata Sil3512 bug?; Promise SATA300 TX4 MisterE
2007-10-17 12:54     ` Alexander Sabourenkov
2007-10-17 15:04       ` Re[2]: " MisterE
2007-10-17 19:21         ` Peter Favrholdt
2007-10-19 12:02           ` Re[2]: " MisterE
2007-10-18 21:07         ` Alexander Sabourenkov
2007-10-19  1:26           ` Tejun Heo
2007-10-19 21:06             ` Alexander Sabourenkov
2007-10-19 22:58               ` Re[2]: " MisterE
2007-10-19 23:58               ` Tejun Heo
2007-10-20 21:50                 ` Alexander Sabourenkov
2007-10-27 13:24                   ` [PATCH-RFC] (was: Re: Sata Sil3512 bug?; Promise SATA300 TX4) Alexander Sabourenkov
2007-10-27 13:44                     ` [PATCH-RFC] Alexander Sabourenkov
2007-10-27 14:08                       ` Re[2]: [PATCH-RFC] MisterE
2007-10-27 15:09                         ` [PATCH-RFC] Alexander Sabourenkov
2007-10-27 15:16                       ` [PATCH-RFC] Promise TX4 implement hw-bug workaround Alexander Sabourenkov
2007-10-27 18:09                         ` Alan Cox
2007-10-27 18:18                           ` Alexander Sabourenkov [this message]
2007-10-27 18:37                             ` Alexander Sabourenkov
2007-10-28  8:21                             ` Jeff Garzik
2007-10-28 20:03                               ` Alexander Sabourenkov
2007-10-28 10:29                         ` Jeff Garzik
2007-10-28 11:52                           ` Alexander Sabourenkov
2007-10-28 11:10                             ` Jeff Garzik
  -- strict thread matches above, loose matches on Subject: below --
2007-10-28 11:03 Mikael Pettersson
2007-10-28 16:32 Mikael Pettersson

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