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From: Jean Delvare <jdelvare@suse.de>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Wolfram Sang <wsa@kernel.org>,
	Terry Bowman <Terry.Bowman@amd.com>,
	Guenter Roeck <linux@roeck-us.net>,
	linux-i2c <linux-i2c@vger.kernel.org>,
	linux-watchdog@vger.kernel.org,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	Robert Richter <rrichter@amd.com>
Subject: Re: [PATCH] i2c: piix4: Replace piix4_smbus driver's cd6h/cd7h port io accesses with mmio accesses
Date: Tue, 18 Jan 2022 14:09:56 +0100	[thread overview]
Message-ID: <20220118140956.1e0538e7@endymion> (raw)
In-Reply-To: <CAHp75VeR4sL1URhf+Vj6_fUjw3wgG98nZd8Mu20NzH1zM590SQ@mail.gmail.com>

On Thu, 13 Jan 2022 12:24:41 +0200, Andy Shevchenko wrote:
> On Thu, Jan 13, 2022 at 9:42 AM Wolfram Sang <wsa@kernel.org> wrote:
> > > > On top of that I'm wondering why slow I/O is used? Do we have anything
> > > > that really needs that or is it simply a cargo-cult?  
> > >
> > > The efch SMBUS & WDT previously only supported a port I/O interface
> > > (until recently) and thus dictated the HW access method.  
> >
> > Is this enough information to start v2 of this series? Or does the
> > approach need more discussion?  
> 
> I dunno why slow I/O is chosen, but it only affects design (read:
> ugliness) of the new code.

I've been wondering about the use of slow (*_p) I/O accessors for some
time too. All the SMBus controller drivers doing that originate from the
lm_sensors project (i2c-ali1535, i2c-ali1563, i2c-ali15x3, i2c-amd756,
i2c-i801, i2c-nforce2, i2c-piix4 and i2c-viapro). So basically *all*
SMBus controller drivers for non-embedded x86.

I suspect that most of this is the result of copy-and-paste from one
driver to the next as support for different chipsets was added in the
late 90's and early 2000's. I wouldn't be surprised if most, if not
all, can be replaced with non-pausing counterparts. But I've been too
shy to give it a try so far.

I must say I find it pretty funny that Andy is asking about it in the
i2c-piix4 driver when the i2c-i801 driver, which he's been helping with
quite a lot in the last few years, does exactly the same.

-- 
Jean Delvare
SUSE L3 Support

  reply	other threads:[~2022-01-18 13:10 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-15 22:18 [PATCH] i2c: piix4: Replace piix4_smbus driver's cd6h/cd7h port io accesses with mmio accesses Terry Bowman
2021-09-07 16:37 ` Jean Delvare
2021-11-05 16:05   ` Jean Delvare
2021-12-13 17:48     ` Terry Bowman
2022-01-04 19:34       ` Terry Bowman
2022-01-06 13:01         ` Wolfram Sang
2022-01-06 18:18         ` Guenter Roeck
2022-01-08 21:49           ` Wolfram Sang
2022-01-10 10:29             ` Andy Shevchenko
2022-01-11 12:39               ` Wolfram Sang
2022-01-11 14:13                 ` Terry Bowman
2022-01-11 14:53                   ` Andy Shevchenko
2022-01-11 14:54                     ` Andy Shevchenko
2022-01-11 15:50                       ` Terry Bowman
2022-01-11 16:17                         ` Andy Shevchenko
2022-01-12  0:40                           ` Terry Bowman
2022-01-13  7:42                         ` Wolfram Sang
2022-01-13 10:24                           ` Andy Shevchenko
2022-01-18 13:09                             ` Jean Delvare [this message]
2022-01-18 14:22       ` Jean Delvare
     [not found] <20210715221828.244536-1-Terry.Bowman () amd ! com>
2021-08-16 16:55 ` Terry Bowman
2021-08-16 17:03 ` Terry Bowman

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