[AMD Official Use Only - General]
> -----Original Message-----
> From: Simek, Michal <michal.simek@xxxxxxx>
> Sent: Monday, July 18, 2022 6:25 PM
> To: Datta, Shubhrajyoti <shubhrajyoti.datta@xxxxxxx>; Lars-Peter Clausen
> <lars@xxxxxxxxxx>; Wolfram Sang <wsa@xxxxxxxxxx>
> Cc: linux-i2c@xxxxxxxxxxxxxxx; git <git@xxxxxxxxxx>
> Subject: Re: [PATCH] i2c: cadence: Support PEC for SMBus block read
>
>
>
> 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?
Tested-by: Shubhrajyoti Datta <Shubhrajyoti.datta@xxxxxxx >
>
> M
