From: Tan Chin Yew <chin.yew.tan@intel.com>
To: Wolfram Sang <wsa@the-dreams.de>,
Jarkko Nikula <jarkko.nikula@linux.intel.com>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH V3] Set sda-hold-time based on ACPI *CNT value
Date: Tue, 28 Mar 2017 16:48:01 +0800 [thread overview]
Message-ID: <1490690882-11623-1-git-send-email-chin.yew.tan@intel.com> (raw)
For I2c to operate correctly under all speed mode, sda-hold-time need to
be perfectly tuned. However, sda-hold-time is precalculated according to
circuit parameter which make it platform-specific.
In order to get accurate sda-hold-time for all platforms, pretuned
sda-hold-time for particular platform is stored in ACPI table and driver
to load the sda holding time from ACPI table.
This patch read the I2c sda-hold-time from ACPI table and assigned the
suitable hold time based on the i2c clock frequency.
Tested on Intel Apollo Lake.
Changes in V3:
- Remove null handling in function dw_i2c_acpi_params.
- Add descriptions to commit message.
Changes in V2:
- The code is realigned according to suggestion.
- "case 400000:" is added on top of "default:" for readability.
Tan Chin Yew (1):
i2c: designware: Get selected speed mode sda-hold-time via ACPI
drivers/i2c/busses/i2c-designware-platdrv.c | 31 ++++++++++++++++++++---------
1 file changed, 22 insertions(+), 9 deletions(-)
--
1.9.1
next reply other threads:[~2017-03-28 8:48 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-28 8:48 Tan Chin Yew [this message]
2017-03-28 8:48 ` [PATCH] i2c: designware: Get selected speed mode sda-hold-time via ACPI Tan Chin Yew
2017-03-28 9:13 ` Andy Shevchenko
2017-03-31 12:12 ` Jarkko Nikula
2017-04-19 18:57 ` Wolfram Sang
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