Re: [PATCH] i2c: imx: Implement errata ERR007805 or e7805 bus frequency limit

[Wolfram Sang <wsa@kernel.org>]

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On Fri, Apr 08, 2022 at 07:15:24PM +0200, Marek Vasut wrote:
> The i.MX8MP Mask Set Errata for Mask 1P33A, Rev. 2.0 has description of
> errata ERR007805 as below. This errata is found on all MX8M{M,N,P,Q},
> MX7{S,D}, MX6{UL{,L,Z},S{,LL,X},S,D,DL,Q,DP,QP} . MX7ULP, MX8Q, MX8X
> are not affected. MX53 and older status is unknown, as the errata
> first appears in MX6 errata sheets from 2016 and the latest errata
> sheet for MX53 is from 2015. Older SoC errata sheets predate the
> MX53 errata sheet. MX8ULP and MX9 status is unknown as the errata
> sheet is not available yet.
> 
> "
> ERR007805 I2C: When the I2C clock speed is configured for 400 kHz,
> the SCL low period violates the I2C spec of 1.3 uS min
> 
> Description: When the I2C module is programmed to operate at the
> maximum clock speed of 400 kHz (as defined by the I2C spec), the SCL
> clock low period violates the I2C spec of 1.3 uS min. The user must
> reduce the clock speed to obtain the SCL low time to meet the 1.3us
> I2C minimum required. This behavior means the SoC is not compliant
> to the I2C spec at 400kHz.
> 
> Workaround: To meet the clock low period requirement in fast speed
> mode, SCL must be configured to 384KHz or less.
> "
> 
> Implement the workaround by matching on the affected SoC specific
> compatible strings and by limiting the maximum bus frequency in case
> the SoC is affected.
> 
> Signed-off-by: Marek Vasut <marex@denx.de>
> Cc: Fabio Estevam <festevam@denx.de>
> Cc: Francesco Dolcini <francesco.dolcini@toradex.com>
> Cc: Marcel Ziswiler <marcel.ziswiler@toradex.com>
> Cc: Oleksij Rempel <linux@rempel-privat.de>
> Cc: Peng Fan <peng.fan@nxp.com>
> Cc: Shawn Guo <shawnguo@kernel.org>
> Cc: NXP Linux Team <linux-imx@nxp.com>
> Cc: linux-arm-kernel@lists.infradead.org
> To: linux-i2c@vger.kernel.org

Applied to for-current, thanks!


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