On 7/18/22 14:37, Datta, Shubhrajyoti wrote:
[AMD Official Use Only - General]
-----Original Message-----
From: Simek, Michal <michal.simek@xxxxxxx>
Sent: Monday, July 18, 2022 2:56 PM
To: Lars-Peter Clausen <lars@xxxxxxxxxx>; Wolfram Sang
<wsa@xxxxxxxxxx>; Datta, Shubhrajyoti <shubhrajyoti.datta@xxxxxxx>
Cc: linux-i2c@xxxxxxxxxxxxxxx; git <git@xxxxxxxxxx>
Subject: Re: [PATCH] i2c: cadence: Support PEC for SMBus block read
On 7/17/22 16:52, Lars-Peter Clausen wrote:
SMBus packet error checking (PEC) is implemented by appending one
additional byte of checksum data at the end of the message. This
provides additional protection and allows to detect data corruption on the
I2C bus.
SMBus block reads support variable length reads. The first byte in the
read message is the number of available data bytes.
The combination of PEC and block read is currently not supported by
the Cadence I2C driver.
* When PEC is enabled the maximum transfer length for block reads
increases from 33 to 34 bytes.
* The I2C core smbus emulation layer relies on the driver updating the
`i2c_msg` `len` field with the number of received bytes. The updated
length is used when checking the PEC.
Add support to the Cadence I2C driver for handling SMBus block reads
with PEC. To determine the maximum transfer length uses the initial
`len` value of the `i2c_msg`. When PEC is enabled this will be 2, when
it is disabled it will be 1.
Once a read transfer is done also increment the `len` field by the
amount of received data bytes.
This change has been tested with a UCM90320 PMBus power monitor,
which
requires block reads to access certain data fields, but also has PEC
enabled by default.
Fixes: df8eb5691c48 ("i2c: Add driver for Cadence I2C controller")
Subject is saying that you adding support for PEC and here you are saying
that it is fixing initial commit.
If this is adding new support I think Fixes tag shouldn't be here.
If it is fixing issue subject should be updated and this Fixes tag kept here.
The rest looks good to me.
Shubhrajyoti: Can you please test?
I have tested the reads and write smbus without packet error check.
Can you please switch it to formal Tested-by: tag?
M
