From: Wolfram Sang <wsa@the-dreams.de>
To: Zhuo-hao Lee <zhuo-hao.lee@intel.com>
Cc: jarkko.nikula@linux.intel.com, andriy.shevchenko@linux.intel.com,
mika.westerberg@linux.intel.com, linux-i2c@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1] i2c: designware: save the preset value of DW_IC_SDA_HOLD
Date: Thu, 8 Sep 2016 22:18:51 +0200 [thread overview]
Message-ID: <20160908201850.GA3166@katana> (raw)
In-Reply-To: <1472283570-31471-1-git-send-email-zhuo-hao.lee@intel.com>
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On Sat, Aug 27, 2016 at 03:39:30PM +0800, Zhuo-hao Lee wrote:
> There are several ways to set the SDA hold time for i2c controller,
> including: Device Tree, built-in device properties and ACPI. However,
> if the SDA hold time is not specified by above method, we should
> read the value, where it is preset by firmware, and save it to
> sda_hold_time. This is needed because when i2c controller enters
> runtime suspend, the DW_IC_SDA_HOLD value will be reset to chipset
> default value. And during runtime resume, i2c_dw_init will be called
> to reconfigure i2c controller. If sda_hold_time is zero, the chipset
> default hold time will be used, that will be too short for some
> platforms. Therefore, to have a better tolerance, the DW_IC_SDA_HOLD
> value should be kept by sda_hold_time.
>
> Signed-off-by: Zhuo-hao Lee <zhuo-hao.lee@intel.com>
Applied to for-current, thanks!
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prev parent reply other threads:[~2016-09-08 20:19 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-27 7:39 [PATCH v1] i2c: designware: save the preset value of DW_IC_SDA_HOLD Zhuo-hao Lee
2016-08-28 12:31 ` Andy Shevchenko
2016-08-29 6:17 ` Jarkko Nikula
2016-08-30 20:59 ` Wolfram Sang
2016-08-31 0:24 ` Lee, Zhuo-hao
2016-09-08 20:18 ` Wolfram Sang [this message]
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