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From: Robert Hancock <hancockr@shaw.ca>
To: benh@kernel.crashing.org
Cc: Mark Lord <liml@rtr.ca>, Allen Martin <AMartin@nvidia.com>,
	Jeff Garzik <jeff@garzik.org>, Tejun Heo <htejun@gmail.com>,
	Gabor Gombas <gombasg@sztaki.hu>,
	linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org,
	Kuan Luo <kluo@nvidia.com>, Peer Chen <pchen@nvidia.com>
Subject: Re: sata_nv + ADMA + Samsung disk problem
Date: Thu, 03 Jan 2008 19:43:39 -0600	[thread overview]
Message-ID: <477D8F4B.6000601@shaw.ca> (raw)
In-Reply-To: <1199394786.7291.21.camel@pasglop>

Benjamin Herrenschmidt wrote:
>> Another thing about the PacDigi core:  one has to be very careful
>> to avoid sequential accesses to sequential PCI locations when
>> programming the chip -- it cannot handle merged register writes.
>>
>> So for any group of sequentially laid out registers, the code has
>> to ensure it never writes two adjacent registers in sequence..
> 
> Ugh ? Write combining isn't permitted on normal registers afaik...
> 
> Ben.

Byte merging can be done by the chipset on MMIO writes (merging multiple 
8 or 16-bit writes into a single 32-bit cycle).

  reply	other threads:[~2008-01-04  1:43 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-08-08 12:08 sata_nv + ADMA + Samsung disk problem Gabor Gombas
2007-08-14  9:30 ` Tejun Heo
2007-08-14 12:02   ` Gabor Gombas
2007-08-16 16:06   ` Gabor Gombas
2007-08-16 18:45     ` Jim Paris
2008-01-01 16:44 ` Gabor Gombas
2008-01-02  3:25   ` Tejun Heo
2008-01-02  4:03     ` Robert Hancock
2008-01-02  4:20       ` Robert Hancock
2008-01-02  4:25         ` Tejun Heo
2008-01-02  6:19           ` Jeff Garzik
2008-01-02  6:39             ` Robert Hancock
2008-01-02  6:55               ` Tejun Heo
2008-01-03  0:27                 ` Robert Hancock
2008-01-02 17:23       ` Allen Martin
2008-01-02 18:57         ` Jeff Garzik
2008-01-02 23:23           ` Allen Martin
2008-01-03  0:21             ` Robert Hancock
2008-01-03  4:14               ` Mark Lord
2008-01-03  4:17               ` Mark Lord
2008-01-03  4:54                 ` Robert Hancock
2008-01-03 15:44                   ` Mark Lord
2008-01-03 15:47                     ` Mark Lord
2008-01-03 21:13                       ` Benjamin Herrenschmidt
2008-01-04  1:43                         ` Robert Hancock [this message]
2008-01-04  5:51                           ` Benjamin Herrenschmidt
2008-01-04  0:41                   ` Allen Martin
2008-01-04  2:51                     ` Robert Hancock
2008-01-08  0:10                     ` Robert Hancock
2008-01-11 23:18                       ` Gabor Gombas
2008-01-12  1:10                         ` Robert Hancock

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