linux-kernel - Re: [PATCHv6 1/2] i2c: designware: introduce a custom scl recovery for SoCFPGA platforms

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Message-ID: <YrN2lxvlP4cWfelY@kunai>
Date:   Wed, 22 Jun 2022 22:07:51 +0200
From:   Wolfram Sang <wsa@...nel.org>
To:     Dinh Nguyen <dinguyen@...nel.org>
Cc:     jarkko.nikula@...ux.intel.com, andriy.shevchenko@...ux.intel.com,
        mika.westerberg@...ux.intel.com, robh+dt@...nel.org,
        krzk+dt@...nel.org, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCHv6 1/2] i2c: designware: introduce a custom scl recovery
 for SoCFPGA platforms


> From the original code, the first mechanism to a recovery is to acquire a
> GPIO for the SCL line and send the 9 SCL pulses, after that, it does a reset
> of the I2C module. For the SOCFPGA part, there is no GPIO line for the SCL,
> thus the I2C module cannot even get a reset. This code allows the function
> to reset the I2C module for SOCFPGA, which is the 2nd part of the recovery
> process.

The second part is totally useless if the client device is holding SDA
low. Which is exactly the situation that recovery tries to fix. As I
said, if you can't control SCL, you don't have recovery.

> > See, this function is named scl_recovery, but there is no SCL involved.
> > This is why I think there is the misunderstanding here.
> > 
> 
> I understand your point here. Perhaps just call it i2c_socfpga_recovery()?

No. adap->bus_recovery_info should be NULL.


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