linux-kernel - Re: [PATCH 1/1] mfd: da9063: Support SMBus and I2C mode

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Message-ID: <20210126082315.GE4903@dell>
Date:   Tue, 26 Jan 2021 08:23:15 +0000
From:   Lee Jones <lee.jones@...aro.org>
To:     Mark Jonas <toertel@...il.com>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Support Opensource <support.opensource@...semi.com>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Adam.Thomson.Opensource@...semi.com, stwiss.opensource@...semi.com,
        marek.vasut@...il.com,
        "RUAN Tingquan (BT-FIR/ENG1-Zhu)" <Tingquan.Ruan@...bosch.com>,
        "Streidl Hubert (BT-FIR/ENG1-Grb)" <Hubert.Streidl@...bosch.com>,
        "Jonas Mark (BT-FIR/ENG1-Grb)" <Mark.Jonas@...bosch.com>
Subject: Re: [PATCH 1/1] mfd: da9063: Support SMBus and I2C mode

On Mon, 25 Jan 2021, Mark Jonas wrote:

> Hi,
> 
> I also intended to send a cover-letter but it was somehow lost on the
> way. Here it is:
> 
> On an NXP i.MX6 Solo processor we are running an application which
> makes use of real-time threads (SCHED_RR). In combination with a
> DA9063 we experienced (rare) random shut-downs and reboots. We found
> that the issue was caused by a combination of the (default) DA9063
> SMBus mode and non-atomic I2C transactions of the i.MX6 I2C driver.
> Because a transaction could be idle for longer than the SMBus clock
> time-out due to a real-time thread the DA9063 would time-out and
> receive the second half of the transaction as an unintended message.
> 
> The solution we are giving to review in this patch is to allow using
> the I2C mode of the DA9063. We kindly ask for feedback and eventually
> hope for an integration to the mainline.
> 
> Because we are on a vendor kernel we were not able to test this patch
> on the current mainline kernel. Though, we tested a (very similar)
> patch on our (close to mainline) Linux 4.14 and 5.4 vendor kernels.

This is the 3rd cover-letter I've received now! :)

-- 
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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