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Date:   Sat, 28 Aug 2021 18:05:40 +0300
From:   Eli Billauer <eli.billauer@gmail.com>
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To:     Christophe JAILLET <christophe.jaillet@wanadoo.fr>
CC:     arnd@arndb.de, gregkh@linuxfoundation.org,
        linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org,
        Christoph Hellwig <hch@infradead.org>
Subject: Re: [PATCH v1 0/4] char: xillybus: Remove usage of the deprecated
 'pci-dma-compat.h' API
References: <cover.1630083668.git.christophe.jaillet@wanadoo.fr>
In-Reply-To: <cover.1630083668.git.christophe.jaillet@wanadoo.fr>
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On 27/08/21 20:17, Christophe JAILLET wrote:
> In [1], Christoph Hellwig has proposed to remove the wrappers in
> include/linux/pci-dma-compat.h.
>    
Xillybus' driver is an example for why this is a good idea. But has this 
been decided upon? Are we sure that there isn't a single platform where 
the DMA mapping for PCI is different from non-PCI, and that such 
platform will never be?

If so, is there any reference to that decision?

I think the best way is to put a comment at the top of pci-dma-compat.h 
saying that the functions in that header file are deprecated and will go 
away soon. That would, more than anything else, convince people like me 
to get rid of those PCI-DMA function calls.

The bonus is that the discussion on the patch inserting that comment, 
along with the decision to apply or reject it, will become the 
authoritative word on this matter.

Thanks,
    Eli