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From: Sergei Shtylyov <sshtylyov@ru.mvista.com>
To: Alan <alan@lxorguk.ukuu.org.uk>
Cc: jgarzik@pobox.com, linux-ide@vger.kernel.org
Subject: Re: [PATCH] pata_sl82c105: wrong assumptions about compatible PIO modes
Date: Tue, 30 Jan 2007 22:08:12 +0300	[thread overview]
Message-ID: <45BF979C.80200@ru.mvista.com> (raw)
In-Reply-To: <20070130190759.3d941365@localhost.localdomain>

Hello.

Alan wrote:

>>Fix the wrong "compatible" PIO mode choices: MWDMA0 has 480 ns cycle while PIO1
>>only has 383 ns cycle, and MWDMA2 timings matchs those of PIO4 exactly.

> Thanks for all this review work

    Oh, I've only started but there's too much to do elsewhere... :-)

>>Frankly speaking, I'm not sure this function is useful or correct at all --
>>with the DMA timings being actually programmed in sl82c105_bmdma_start()...

> It ought to be right
> - bmdma_start loads the real DMA mode
> - set_dmamode/set_piomode load the right PIO timings

    You just said set_piomode() is called before set_dmamode() by the libata 
core anyway -- there seems to be no point in re-writing the modes until the 
actual DMA is started.

> - bmdma_stop restores the right PIO timings

>>And the issue of the same registers being used for both PIO and DMA timings is
>>not specific for this driver at all but seems to be addressed only by it...

> For most drivers (those using the ata_timing interface) the timing merge
> is done by ata_timing_compute(). 

    Ah...

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

> Acked-by: Alan Cox <alan@redhat.com>

MBR, Sergei

  reply	other threads:[~2007-01-30 19:08 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-01-30 17:40 [PATCH] pata_sl82c105: wrong assumptions about compatible PIO modes Sergei Shtylyov
2007-01-30 19:07 ` Alan
2007-01-30 19:08   ` Sergei Shtylyov [this message]
2007-01-30 19:27     ` Alan
2007-02-07  0:37 ` Jeff Garzik

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