From: Sergei Shtylyov <sshtylyov@ru.mvista.com>
To: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Cc: linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org,
Patrick Horn <phrh@yahoo.com>,
Russell King <rmk+lkml@arm.linux.org.uk>
Subject: Re: [PATCH 1/2] ide: don't allow DMA to be enabled if CONFIG_IDEDMA_{ICS,PCI}_AUTO=n
Date: Sun, 10 Aug 2008 20:30:21 +0400 [thread overview]
Message-ID: <489F179D.2010101@ru.mvista.com> (raw)
In-Reply-To: <200703152145.40644.bzolnier@gmail.com>
Hello.
Bartlomiej Zolnierkiewicz wrote:
> [PATCH] ide: don't allow DMA to be enabled if CONFIG_IDEDMA_{ICS,PCI}_AUTO=n
> For CONFIG_IDEDMA_{ICS,PCI}_AUTO=n and/or "ide=nodma" option the host/device
Not only that: it also would affect CompactFlash with no DMA support but
with DMA autotuning enabled in IDE core...
> are not programmed for DMA and it is also explicitly disabled by ide_set_dma()
> (->ide_dma_check returns "-1"). However the code responsible for manually
> enabling DMA ("hdparm -d 1") has a bug which results in DMA being erroneously
> enabled - ide_set_dma() incorrectly passes "0" return value to set_using_dma().
Heh, I've just run into this myself while trying to retro-fit Palmchip
BK3710 IDE driver into 2.6.18 properly.
> This may work if BIOS/firmware configured the host/device for DMA and chipset
> allows independent configuration of DMA/PIO modes but won't work after suspend
> and is generally unsafe on many chipsets (possibly including data corruption
> if the same registers are used for DMA/PIO timings).
Timeouts ensued in my case...
WBR, Sergei
prev parent reply other threads:[~2008-08-10 16:30 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-03-15 20:45 [PATCH 1/2] ide: don't allow DMA to be enabled if CONFIG_IDEDMA_{ICS,PCI}_AUTO=n Bartlomiej Zolnierkiewicz
2008-08-10 16:30 ` Sergei Shtylyov [this message]
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