From mboxrd@z Thu Jan 1 00:00:00 1970 From: wsa@the-dreams.de (Wolfram Sang) Date: Tue, 13 Jan 2015 12:42:37 +0100 Subject: [PATCH v5] i2c: rk3x: fix bug that cause measured high_ns doesn't meet I2C specification In-Reply-To: <1418295760-19639-1-git-send-email-addy.ke@rock-chips.com> References: <1418277650-25215-1-git-send-email-addy.ke@rock-chips.com> <1418295760-19639-1-git-send-email-addy.ke@rock-chips.com> Message-ID: <20150113114237.GC7660@katana> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, Dec 11, 2014 at 07:02:40PM +0800, Addy Ke wrote: > The number of clock cycles to be written into the CLKDIV register > that determines the I2C clk high phase includes the rise time. > So to meet the timing requirements defined in the I2C specification > which defines the minimal time SCL has to be high, the rise time > has to taken into account. The same applies to the low phase with > falling time. > > In my test on RK3288-Pink2 board, which is not an upstream board yet, > if external pull-up resistor is 4.7K, rise_ns is about 700ns. > So the measured high_ns is about 3900ns, which is less than 4000ns > (the minimum high_ns in I2C specification for Standard-mode). > > To fix this bug min_low_ns should include fall time and min_high_ns > should include rise time. > > This patch merged the patch from chromium project which can get the > rise and fall times for signals from the device tree. This allows us > to more accurately calculate timings. see: > https://chromium-review.googlesource.com/#/c/232774/ > > Signed-off-by: Addy Ke Applied to for-next, thanks! I fixed the typo Doug mentioned. Please send new patches as seperate threads, not as a reply to the old patch. -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 819 bytes Desc: Digital signature URL: