From: Wolfram Sang <wsa@the-dreams.de>
To: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>,
linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] i2c / ACPI: Pick the first address if device has multiple
Date: Tue, 13 Jan 2015 17:48:29 +0100 [thread overview]
Message-ID: <20150113164829.GO7660@katana> (raw)
In-Reply-To: <1421167477.4459.229.camel@spandruv-desktop.jf.intel.com>
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On Tue, Jan 13, 2015 at 08:44:37AM -0800, Srinivas Pandruvada wrote:
> On Tue, 2015-01-13 at 16:50 +0100, Wolfram Sang wrote:
> > On Mon, Dec 29, 2014 at 03:48:48PM +0200, Mika Westerberg wrote:
> > > ACPI specification allows I2C devices with multiple addresses. The current
> > > implementation goes over all addresses and assigns the last one to the
> > > device. This is typically not the primary address of the device.
> > >
> > > Instead of doing that we assign the first address to the device and then
> > > let the driver handle rest of the addresses as it wishes.
> > >
> > > Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> > > Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
> >
> > Yes, seems better than what we do know. But maybe taking the lowest
> > address is a bit better heuristic than taking the first address?
> > Not sure, though...
> The problem in taking lowest is that in many cases in current devices,
> the lowest address may end being 0x0C, which is reserved address for
> SMBUS (ARA). This will require different handling. Unfortunately ACPI
> doesn't have a way to distinguish whether SMBUS support is desired or
> not.
> The other option is to skip all reserved addresses for SMBUS also and
> then create on the lowest.
Well, this makes me think that Mika's approach is probably the sanest
one...
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next prev parent reply other threads:[~2015-01-13 16:48 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-12-29 13:48 [PATCH] i2c / ACPI: Pick the first address if device has multiple Mika Westerberg
2015-01-13 15:50 ` Wolfram Sang
2015-01-13 16:44 ` Srinivas Pandruvada
2015-01-13 16:48 ` Wolfram Sang [this message]
2015-01-13 17:00 ` Mika Westerberg
2015-01-14 10:55 ` Wolfram Sang
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