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Re: [PATCH] driver/i2c/mux: Add register based mux i2c-mux-reg

From Alexander Sverdlin <alexander.sverdlin@nokia.com>
Newsgroups linux.kernel
Subject Re: [PATCH] driver/i2c/mux: Add register based mux i2c-mux-reg
Date 2015-06-18 10:00 +0200
Message-ID <pCCTU-28V-1@gated-at.bofh.it> (permalink)
References <pC2Qr-GT-31@gated-at.bofh.it> <pCn8t-4W5-5@gated-at.bofh.it> <pCoHf-704-9@gated-at.bofh.it>
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Hello!

On 17/06/15 18:43, ext York Sun wrote:
>> > Yeah, this is really bad idea. You maybe want something like
>> > __iomem "cookie" here instead of this bare pointer.
> Let me try.
> 

Could you think about different access widths, please?
Not all buses are 32-bits wide and even on 64-bit CPUs one might have 16-bit bus
and 32 bits accesses are not allowed or perform two accesses, etc...

So to cover the use-cases which I see one needs to have a possibility to select between
__raw_writeb()/__raw_writew()/__raw_writel()/__raw_writeq() (now that I'm thinking about
it, I think these native-Endianness functions are preferred and if one has a bus with
different Endianness he should think about the conversion in the reg property of subnodes).

Very important is readback with corresponding __raw_read*(), but maybe you want to do
this optional via additional DT property...

-- 
Best regards,
Alexander Sverdlin.
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Thread

[PATCH] driver/i2c/mux: Add register based mux i2c-mux-reg York Sun <yorksun@freescale.com> - 2015-06-16 19:30 +0200
  Re: [PATCH] driver/i2c/mux: Add register based mux i2c-mux-reg Alexander Sverdlin <alexander.sverdlin@nokia.com> - 2015-06-18 09:50 +0200
    Re: [PATCH] driver/i2c/mux: Add register based mux i2c-mux-reg Paul Bolle <pebolle@tiscali.nl> - 2015-06-18 10:10 +0200
  Re: [PATCH] driver/i2c/mux: Add register based mux i2c-mux-reg Alexander Sverdlin <alexander.sverdlin@nokia.com> - 2015-06-18 10:00 +0200

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