From mboxrd@z Thu Jan  1 00:00:00 1970
From: Thomas Chou <thomas@wytron.com.tw>
Date: Mon, 19 Oct 2015 16:18:06 +0800
Subject: [U-Boot] [PATCH v4] nios2: convert dma_alloc_coherent to use
 malloc_cache_aligned
In-Reply-To: <20151019075225.1363f49f@lilith>
References: <1444013823-11909-1-git-send-email-thomas@wytron.com.tw>
 <1444627783-15105-1-git-send-email-thomas@wytron.com.tw>
 <201510121232.56484.marex@denx.de> <561BADA7.1050008@wytron.com.tw>
 <20151019075225.1363f49f@lilith>
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Hi Albert,

On 10/19/2015 01:52 PM, Albert ARIBAUD wrote:
> Not sure I'm getting this, so for my own education: what prevents from
> invalidating the cache, or IOW, what would happen if it was invalidated
> at this point rather than flushed?

This is a hardware limitation. The nios2 cpu with 4 bytes dcache line 
size does not support the initda instruction, which is needed to 
invalidate dcache.

Recently we added a check, if the nios2 cpu support initda instruction, 
then we use invalidate_dcache, otherwise we use flush_dcache.

Best regards,
Thomas