linux-kernel - RE: [PATCH V12 3/5] i2c: tegra: Add DMA support

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Message-ID: <BYAPR12MB3398B4A862E4BFA5344AE461C26F0@BYAPR12MB3398.namprd12.prod.outlook.com>
Date:   Wed, 6 Feb 2019 13:29:53 +0000
From:   Sowjanya Komatineni <skomatineni@...dia.com>
To:     Dmitry Osipenko <digetx@...il.com>,
        "thierry.reding@...il.com" <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Mantravadi Karthik <mkarthik@...dia.com>,
        Shardar Mohammed <smohammed@...dia.com>,
        Timo Alho <talho@...dia.com>
CC:     "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>
Subject: RE: [PATCH V12 3/5] i2c: tegra: Add DMA support


> > 
> >>>> BTW, I'm seeing "atmel_mxt_ts 0-004c: Warning: Info CRC error - device=0xF436DC file=0x000000" whithout making any modifications to the original patch as well and it shall not happen, hence there is bug somewhere. Probably FIFO triggers are still not set up correctly... ?
> >>>>
> >>>>
> >>> In snippet you sent, I see you are forcing dma_burst to 1 always which is what set for fifo trigger levels as well and also you are forcing dma all the time.
> >>> So always it will be 1 word dma burst and 1 word trigger level and that should not be an issue.
> >>>
> >>
> >> I reverted that snippet, this log is collected with the yours original patch.
> >>
> > From atmel driver, looks like this warning is from maxt_update_cfg and 
> > due to CRC mismatch and above values shows read data CRC is 0Xf436dc which is compared against info_crc of all 0's Info_crc is based on raw config file and somehow its all 0's. this is not based on data read thru i2c.
> > data->info_crc computed on data read is 0Xf436dc
> > 
> > This warning is not related to I2C transfer
> > 
>
> It doesn't happen with the I2C PIO mode. Seems it means that the I2C reads out the 0xF436DC value instead of 0x000000.. if I'm not missing anything.
>
Log that you shared this warning, doesn’t show any i2c failures with atmel and CRC based on i2c read  data is 0Xf436dc.
During this log, there are not DMA timeouts associated during this warning timeframe. So i2c read data is thru DMA which is non-zero.