From: Alexander Sverdlin <alexander.sverdlin-xNZwKgViW5gAvxtiuMwx3w@public.gmane.org>
To: ext York Sun <yorksun-KZfg59tc24xl57MIdRCFDg@public.gmane.org>,
wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org
Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Peter Korsgaard
<peter.korsgaard-ob4gmnvZ1/cAvxtiuMwx3w@public.gmane.org>
Subject: Re: [PATCH] driver/i2c/mux: Add register based mux i2c-mux-reg
Date: Thu, 18 Jun 2015 09:58:22 +0200 [thread overview]
Message-ID: <55827A1E.4020608@nokia.com> (raw)
In-Reply-To: <5581A3CA.4050805-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
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.
WARNING: multiple messages have this Message-ID (diff)
From: Alexander Sverdlin <alexander.sverdlin@nokia.com>
To: ext York Sun <yorksun@freescale.com>, wsa@the-dreams.de
Cc: linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org,
Peter Korsgaard <peter.korsgaard@barco.com>
Subject: Re: [PATCH] driver/i2c/mux: Add register based mux i2c-mux-reg
Date: Thu, 18 Jun 2015 09:58:22 +0200 [thread overview]
Message-ID: <55827A1E.4020608@nokia.com> (raw)
In-Reply-To: <5581A3CA.4050805@freescale.com>
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.
next prev parent reply other threads:[~2015-06-18 7:58 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-16 17:28 [PATCH] driver/i2c/mux: Add register based mux i2c-mux-reg York Sun
2015-06-16 17:28 ` York Sun
[not found] ` <1434475692-4611-1-git-send-email-yorksun-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
2015-06-17 8:54 ` Paul Bolle
2015-06-17 8:54 ` Paul Bolle
2015-06-17 15:00 ` Alexander Sverdlin
2015-06-17 15:00 ` Alexander Sverdlin
[not found] ` <55818BAB.5090605-xNZwKgViW5gAvxtiuMwx3w@public.gmane.org>
2015-06-17 16:03 ` Paul Bolle
2015-06-17 16:03 ` Paul Bolle
2015-06-18 7:40 ` Alexander Sverdlin
2015-06-18 7:40 ` Alexander Sverdlin
[not found] ` <558275F1.5020100-xNZwKgViW5gAvxtiuMwx3w@public.gmane.org>
2015-06-18 8:08 ` Paul Bolle
2015-06-18 8:08 ` Paul Bolle
2015-06-18 9:04 ` Alexander Sverdlin
2015-06-18 9:04 ` Alexander Sverdlin
[not found] ` <5582899B.9030307-xNZwKgViW5gAvxtiuMwx3w@public.gmane.org>
2015-06-18 9:32 ` Paul Bolle
2015-06-18 9:32 ` Paul Bolle
2015-06-18 9:42 ` Alexander Sverdlin
2015-06-18 9:42 ` Alexander Sverdlin
2015-06-18 9:55 ` Paul Bolle
2015-06-17 15:03 ` Alexander Sverdlin
2015-06-17 15:03 ` Alexander Sverdlin
[not found] ` <55818C3C.8000704-xNZwKgViW5gAvxtiuMwx3w@public.gmane.org>
2015-06-17 16:43 ` York Sun
2015-06-17 16:43 ` York Sun
[not found] ` <5581A3CA.4050805-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
2015-06-18 7:58 ` Alexander Sverdlin [this message]
2015-06-18 7:58 ` Alexander Sverdlin
2015-08-15 20:23 ` Wolfram Sang
2015-08-15 20:23 ` Wolfram Sang
2015-08-17 16:37 ` York Sun
2015-08-17 16:37 ` York Sun
[not found] ` <55D20DC9.2060304-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
2015-08-18 16:44 ` Wolfram Sang
2015-08-18 16:44 ` Wolfram Sang
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