linux-kernel - Re: [PATCH] ARC: io.h: Implement reads{x}()/writes{x}()

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Message-ID: <2d58c25b-60d0-4616-d2d2-ea490a7261f5@synopsys.com>
Date:   Thu, 29 Nov 2018 12:53:33 +0000
From:   Jose Abreu <jose.abreu@...opsys.com>
To:     David Laight <David.Laight@...LAB.COM>,
        "linux-snps-arc@...ts.infradead.org" 
        <linux-snps-arc@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Vineet Gupta <vineet.gupta1@...opsys.com>,
        Alexey Brodkin <alexey.brodkin@...opsys.com>,
        Joao Pinto <joao.pinto@...opsys.com>,
        "Vitor Soares" <vitor.soares@...opsys.com>
Subject: Re: [PATCH] ARC: io.h: Implement reads{x}()/writes{x}()

On 29-11-2018 12:47, David Laight wrote:
> From: Jose Abreu
>> Sent: 29 November 2018 12:42
>>
>> Some ARC CPU's do not support unaligned loads/stores. Currently, generic
>> implementation of reads{b/w/l}()/writes{b/w/l}() is being used with ARC.
>> This can lead to misfunction of some drivers as generic functions do a
>> plain dereference of a pointer that can be unaligned.
>>
>> Let's use {get/put}_unaligned() helper instead of plain dereference of
>> pointer in order to fix this.
> Is it worth adding a check for the pointer being aligned?

We could but then we would need to know which CPU version is
currently running because some ARC processors support unaligned
accesses.

Thanks and Best Regards,
Jose Miguel Abreu

>
> 	David
>
> -
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