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From: Sergei Shtylyov <sshtylyov@ru.mvista.com>
To: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Cc: linux-ide@vger.kernel.org
Subject: Re: [PATCH] trm290: do hook dma_host_{on,off} methods (take 2)
Date: Fri, 28 Dec 2007 22:41:26 +0300	[thread overview]
Message-ID: <47755166.7030809@ru.mvista.com> (raw)
In-Reply-To: <200712271705.32867.bzolnier@gmail.com>

Hello.

Bartlomiej Zolnierkiewicz wrote:

>>Using default methods caused the chip's DMA PRD count registers, inadvertently
>>starting DMA!  While fixing it, also do:

> nasty, this could possibly explain the following trm290.c hack:

    Frankly speaking, I'm not sure it's that destructive: the register in 
question is accessed by inw()/outw() while the genric code would only "spoil" 
it by inb(). So, I don't know if this would be access to the same register as
outw() does (that write starts DMA, and it is a number of 32-bit words in PRD 
table - 1). Actually, the PRD address is loaded by 32-bit write at address 2 
bytes below the one in question, and so overlaps our register -- the chip must 
be looking at byte enables when deciding what register is addressed).

> ...
> #if 0 /* play it safe for now */
			  IDE_HFLAG_TRUST_BIOS_FOR_DMA |
> #endif
> ...

>>- get rid of the 'ide_' prefixes in several functions for which the prefix in
>>  the method's name has been 'ide_' ectomized already;

>>- align the code hooking the IDE DMA methods in init_hwif_trm290()...

>>---
>>Fixed the header, added 'static' to the new method definitions.
>>The patch is against Linus' kernel tree...

>>Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>

> applied

    The next patch is cooking... :-)

WBR, Sergei

      reply	other threads:[~2007-12-28 19:40 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-12-27 10:55 [PATCH] trm290: do hook dma_host_{on,off} methods (take 2) Sergei Shtylyov
2007-12-27 16:05 ` Bartlomiej Zolnierkiewicz
2007-12-28 19:41   ` Sergei Shtylyov [this message]

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