From: Dinh Nguyen <dinguyen@kernel.org>
To: Wolfram Sang <wsa@kernel.org>,
jarkko.nikula@linux.intel.com, andriy.shevchenko@linux.intel.com,
mika.westerberg@linux.intel.com, robh+dt@kernel.org,
krzk+dt@kernel.org, linux-i2c@vger.kernel.org,
linux-kernel@vger.kernel.org, devicetree@vger.kernel.org
Subject: Re: [PATCHv6 1/2] i2c: designware: introduce a custom scl recovery for SoCFPGA platforms
Date: Tue, 12 Jul 2022 07:41:06 -0500 [thread overview]
Message-ID: <c765455f-c1b9-2da0-675e-591f7c268d99@kernel.org> (raw)
In-Reply-To: <YrN2lxvlP4cWfelY@kunai>
Hi Wolfram,
On 6/22/22 15:07, Wolfram Sang wrote:
>
>> 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.
>
This is recovery of the master and not the slave. We have a customer
that is the using I2C with the signals routed through the FPGA, and thus
are not GPIO. During a timeout, with this code, the driver is able to
recover the master.
Dinh
next prev parent reply other threads:[~2022-07-12 12:41 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-20 23:01 [PATCHv6 1/2] i2c: designware: introduce a custom scl recovery for SoCFPGA platforms Dinh Nguyen
2022-06-20 23:01 ` [PATCHv6 2/2] dt-bindings: i2c: dw: Add Intel's SoCFPGA I2C controller Dinh Nguyen
2022-06-21 14:14 ` [PATCHv6 1/2] i2c: designware: introduce a custom scl recovery for SoCFPGA platforms Jarkko Nikula
2022-06-21 21:37 ` Wolfram Sang
2022-06-22 13:45 ` Dinh Nguyen
2022-06-22 20:07 ` Wolfram Sang
2022-07-12 12:41 ` Dinh Nguyen [this message]
2022-07-12 12:52 ` Dinh Nguyen
2022-07-12 13:29 ` Wolfram Sang
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