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

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Date:   Wed, 6 Feb 2019 16:34:52 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Sowjanya Komatineni <skomatineni@...dia.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

06.02.2019 16:30, Sowjanya Komatineni пишет:
> 
> 
>>>
>>>>>> 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.
> 
> Do you see DMA timeouts associated with this warning? I meant any DMA or I2C timeout during that time frame of warning?
> 

Actually you're right, my bad. That atmel error and atmel I2C timeout (due to I2C_ERR_NO_ACK) happens in the PIO mode too, hence that part is fine.

PIO log:

[    1.028889] atmel_mxt_ts 0-004c: Warning: Info CRC error - device=0xF436DC file=0x000000
[    1.078907] atmel_mxt_ts 0-004c: Resetting device
[    1.128646] usb 1-1: new full-speed USB device number 2 using tegra-ehci
[    1.198708] atmel_mxt_ts 0-004c: __mxt_read_reg: i2c transfer failed (-121)
[    1.198732] atmel_mxt_ts 0-004c: Failed to read 28 messages (-121)