From: Hans de Goede <hdegoede@redhat.com>
To: Wolfram Sang <wsa@the-dreams.de>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Jarkko Nikula <jarkko.nikula@linux.intel.com>,
linux-i2c@vger.kernel.org
Subject: Re: [PATCH] i2c: designware: Round down ACPI provided clk to nearest supported clk
Date: Tue, 29 Aug 2017 22:27:14 +0200 [thread overview]
Message-ID: <3cc3df29-b2b5-4a2a-fce4-a9d2302fee54@redhat.com> (raw)
In-Reply-To: <20170829201826.htdia6olxs3j5k66@ninjato>
Hi,
On 08/29/2017 10:18 PM, Wolfram Sang wrote:
> Hi,
>
>>> I dunno what standard says if we may or may not use 100 kHz as a last
>>> resort even for speeds defined less than 100 kHz.
>>
>> The < 100000 case is for when i2c_acpi_find_bus_speed() returns 0, so
>> that we then keep it 0, in which case the code a bit lower will pick
>> a default.
>
> This is fine by me.
>
>> Since speeds < 100000 are clearly not valid treating them
>
> Here I wonder: Not valid because of ACPI specs? Because I2C specs surely
> allow speeds < 100kHz.
The speed comes from an ACPI entry describing an i2c client,
any compliant i2c client must at least support 100KHz, right ?
Alternatively I could wrap the entire round-down for loop in
an if (acpi_speed) {} block.
Regards,
Hans
next prev parent reply other threads:[~2017-08-29 20:27 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-29 12:08 [PATCH] i2c: designware: Round down ACPI provided clk to nearest supported clk Hans de Goede
2017-08-29 12:22 ` Andy Shevchenko
2017-08-29 12:52 ` Hans de Goede
2017-08-29 14:12 ` Jarkko Nikula
2017-08-29 20:18 ` Wolfram Sang
2017-08-29 20:27 ` Hans de Goede [this message]
2017-08-29 21:00 ` Wolfram Sang
2017-08-30 1:23 ` Phil Reid
2017-08-30 7:37 ` Jarkko Nikula
2017-08-31 18:29 ` Wolfram Sang
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