[ECOS] [Fwd: AT91SAM7SE DMA with external SDRAM]

[ECOS] [Fwd: AT91SAM7SE DMA with external SDRAM]

[Jonathan Larmour]

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This was misaddressed....

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From: <jc.caquet@kerlink.fr>
To: <ecos-discuss-owner@ecos.sourceware.org>
Subject: AT91SAM7SE DMA with external SDRAM
Date: Fri, 21 Sep 2007 10:08:45 +0200
Message-ID: <20070921080858.AB3A13FE4@jifvik.dyndns.org>

Dear all,
we are facing a pb when sending data over serial link on AT91SAM7SE-EK
board. We use external SDRAM connected on EBI, this SDRAM is OK as we made
some intensive read/write tests over the whole memory.
Ecos implementation of USART drivers use DMA (eg PDC) when sending
characters, and since output buffer is located in SDRAM output characters
are sometimes missing or sometimes replaced by another.
We don't have any trouble when output buffer is located in internal SRAM,
and we only have to send a few characters to see the pb. 
We checked that characters are still correct in SDRAM after transmission,
and we also checked that the characters we read on the serial line are OK.

Does anybody know if there are some restrictions/bugs when using DMA with
external memory connected on EBI ?

JC



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Re: [ECOS] [Fwd: AT91SAM7SE DMA with external SDRAM]

[Andrew Lunn]

> From: jc.caquet@kerlink.fr
> To: ecos-discuss-owner@ecos.sourceware.org
> Subject: AT91SAM7SE DMA with external SDRAM
> Date: Fri, 21 Sep 2007 10:08:45 +0200
> X-Spam-Status: No, score=2.9 required=5.0 tests=AWL,BAYES_60,
> 	MSGID_FROM_MTA_ID,NO_REAL_NAME autolearn=no version=3.0.4
> 
> Dear all,
> we are facing a pb when sending data over serial link on AT91SAM7SE-EK
> board. We use external SDRAM connected on EBI, this SDRAM is OK as we made
> some intensive read/write tests over the whole memory.

This might not be conclusive. The DMA engine could be doing a
different type of memory access as to normal reads/writes.

> Does anybody know if there are some restrictions/bugs when using DMA with
> external memory connected on EBI ?

You should probably be asking Atmel....

    Andrew

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RE: [ECOS] [Fwd: AT91SAM7SE DMA with external SDRAM]

[jc.caquet]

-----Message d'origine-----
De : ecos-discuss-owner@ecos.sourceware.org
[mailto:ecos-discuss-owner@ecos.sourceware.org] De la part de Andrew Lunn
Envoyé : vendredi 21 septembre 2007 13:20
À : eCos discussion
Objet : Re: [ECOS] [Fwd: AT91SAM7SE DMA with external SDRAM]

> From: jc.caquet@kerlink.fr
> To: ecos-discuss-owner@ecos.sourceware.org
> Subject: AT91SAM7SE DMA with external SDRAM
> Date: Fri, 21 Sep 2007 10:08:45 +0200
> X-Spam-Status: No, score=2.9 required=5.0 tests=AWL,BAYES_60,
> 	MSGID_FROM_MTA_ID,NO_REAL_NAME autolearn=no version=3.0.4
> 
> Dear all,
> we are facing a pb when sending data over serial link on AT91SAM7SE-EK
> board. We use external SDRAM connected on EBI, this SDRAM is OK as we made
> some intensive read/write tests over the whole memory.

This might not be conclusive. The DMA engine could be doing a
different type of memory access as to normal reads/writes.

> Does anybody know if there are some restrictions/bugs when using DMA with
> external memory connected on EBI ?

You should probably be asking Atmel....

    Andrew


We just got an answer from ATMEL, this pb has already been reported, they
're looking for a workaround.
JC

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