From: Simon Schwarz <simonschwarzcor@googlemail.com>
To: u-boot@lists.denx.de
Subject: [U-Boot] Bottleneck of NAND copy speed
Date: Tue, 13 Sep 2011 15:18:54 +0200 [thread overview]
Message-ID: <4E6F583E.9070804@gmail.com> (raw)
In-Reply-To: <4E6E0151.1050708@ge.com>
On 09/12/2011 02:55 PM, Nick Thompson wrote:
> On 12/09/11 12:21, Simon Schwarz wrote:
>> Hi List,
>>
>> ATM I'm working on a DMA transfer from NAND to RAM of the Linux-image in
>> my SPL.
>>
>> I?m searching for the speed bottleneck of the MT29F1G16ABBHC-ET
>> NAND-Flash on the devkit8000 (OMAP3).
>>
>> From the timings I set on the GPMC I calced a max. speed of around 26
>> MiB/s. In my measurements I have a speed of around 10 MiB/s.
>>
>> Here is the image of my the calculation:
>> https://docs.google.com/leaf?id=0B_wpO5K0MQSlYTcxMWVlOGEtY2FmYy00ODMyLWE1MTUtN2ZiZGViOWVhMzYw&hl=en_US
>>
>> tcmd: The time for the initial read command
>> twr: time to write the address
>> tDn: Time for a 16bit read of Data
>>
>> Does anyone has an idea where the bottleneck could be? Is my calculation
>> wrong?
>> (ecc is done parallel to the DMA transfer).
>
> I only had a quick look at your calculation, but didn't notice anything to account
> for the NAND copy to read cache (data ready) time of the NAND device.
>
> Nick.
Ahh you mean t_R (Page read time) right?
Taking this into account I would expect something around 19,45 MiB/s.
Thank you!
Simon
next prev parent reply other threads:[~2011-09-13 13:18 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-12 11:21 [U-Boot] Bottleneck of NAND copy speed Simon Schwarz
2011-09-12 11:43 ` Wolfgang Denk
2011-09-13 13:13 ` Simon Schwarz
2011-09-12 12:55 ` Nick Thompson
2011-09-13 13:18 ` Simon Schwarz [this message]
2011-09-13 19:53 ` Scott Wood
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