linux-kernel - Re: [PATCH 2/2] i2c: designware: enable High-speed mode for pcidrv

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Message-ID: <20151023200407.GC1520@katana>
Date:	Fri, 23 Oct 2015 22:04:07 +0200
From:	Wolfram Sang <wsa@...-dreams.de>
To:	Xiang Wang <wangxfdu@...il.com>
Cc:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
	xiang.a.wang@...el.com, linux-i2c@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] i2c: designware: enable High-speed mode for pcidrv


> > Should it (ACPI walk) be done in PCI case as well? If so, then it needs
> > to be done up to i2c-core. There you may adjust the bus speed whenever
> > slave device is enumerated.
> >
> I think the "ACPI walk for bus speed" also works for PCI case. It'll
> be good to do this in i2c-core.
> By doing this we can get a minimum device speed for this bus. I2C bus
> drivers can use this speed to set corresponding mode into i2c
> controller.
> Waiting for comments from others.
> 
> > For PCI case you have still to have hardcoded values and it should be
> > maximum supported by the bus I think. When you have implemented above
> > algorithm you may do this safely. Am I missing something?
> Agree. It'll be safer to set a hardcoded maximum supported speed of
> the bus for PCI case.
> I2C bus driver can use MIN(speed_get_by_ACPI_walk,
> hardcoded_max_supported_speed) for bus speed.

Do I read this correctly that you agreed on an alternative path so this
series can be discarded?


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