From: Sergei Shtylyov <sshtylyov@ru.mvista.com>
To: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
linux-ide@vger.kernel.org
Subject: Re: ide patches
Date: Sun, 29 Jul 2007 14:48:58 +0400 [thread overview]
Message-ID: <46AC709A.6060002@ru.mvista.com> (raw)
In-Reply-To: <200707232322.22129.bzolnier@gmail.com>
Bartlomiej Zolnierkiewicz wrote:
>>>Ok, there's a combination of things here:
>>> - First, doing a set_pio from userland (hdparm -p XX) causes the kernel
>>>to disable DMA, which I think is incorrect. It's not the case with
>>>2.6.22 from my quick tests. The problem is that ide_config_drive_speed
>>>disables DMA, but only re-enables it when setting a DMA speed. I think
> The problem is that _many_ chipsets don't support separate PIO and DMA
> timings so disabling DMA while programming chipset for PIO timings is a
> necessity for them.
Actually, I didn't quite follow (as I'm afraid Ben also :-). Do you mean
the fact that the DMA timings may get overwritten (which happens due to the
failure of the drivers to handle the shared PIO/DMA timing registers, and in
some cases by "coupling" PIO to UltraDMA timings for no apparent reasons which
leads to disabling UltraDMA when PIO is being programmed)?
MBR, Sergei
next prev parent reply other threads:[~2007-07-29 10:46 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-07-22 18:19 [PATCH] ide-pmac: fix drive->init_speed reporting Bartlomiej Zolnierkiewicz
2007-07-22 21:50 ` Benjamin Herrenschmidt
2007-07-23 21:20 ` Bartlomiej Zolnierkiewicz
2007-07-22 23:55 ` ide patches Benjamin Herrenschmidt
2007-07-23 1:21 ` Benjamin Herrenschmidt
2007-07-23 1:57 ` Benjamin Herrenschmidt
2007-07-23 2:01 ` Benjamin Herrenschmidt
2007-07-23 13:50 ` Sergei Shtylyov
2007-07-23 21:49 ` Benjamin Herrenschmidt
2007-07-23 21:22 ` Bartlomiej Zolnierkiewicz
2007-07-23 22:00 ` Benjamin Herrenschmidt
2007-07-29 10:48 ` Sergei Shtylyov [this message]
2007-07-29 14:39 ` Bartlomiej Zolnierkiewicz
2007-07-23 13:16 ` Sergei Shtylyov
2007-07-23 21:48 ` Benjamin Herrenschmidt
2007-07-23 22:06 ` Sergei Shtylyov
2007-07-23 22:08 ` Benjamin Herrenschmidt
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