linux-kernel - Re: [V2] i2c: i2c-qcom-geni: Correct I2C TRE sequence

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Date: Thu, 1 Feb 2024 15:49:52 +0530
From: Viken Dadhaniya <quic_vdadhani@...cinc.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
CC: <andersson@...nel.org>, <konrad.dybcio@...aro.org>,
        <andi.shyti@...nel.org>, <linux-arm-msm@...r.kernel.org>,
        <linux-i2c@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <vkoul@...nel.org>, <quic_bjorande@...cinc.com>,
        <manivannan.sadhasivam@...aro.org>, <quic_msavaliy@...cinc.com>,
        <quic_vtanuku@...cinc.com>
Subject: Re: [V2] i2c: i2c-qcom-geni: Correct I2C TRE sequence



On 1/30/2024 5:19 AM, Dmitry Baryshkov wrote:
> On Mon, 29 Jan 2024 at 08:10, Viken Dadhaniya <quic_vdadhani@...cinc.com> wrote:
>>
>> For i2c read operation, we are getting gsi mode timeout due
>> to malformed TRE(Transfer Ring Element). Currently we are
>> configuring incorrect TRE sequence in gpi driver
>> (drivers/dma/qcom/gpi.c) as below
>>
>> - Sets up CONFIG
>> - Sets up DMA tre
>> - Sets up GO tre
>>
>> As per HPG(Hardware programming guide), We should configure TREs in below
>> sequence for any i2c transfer
>>
>> - Sets up CONFIG tre
>> - Sets up GO tre
>> - Sets up DMA tre
> 
> It is not clear how this is relevant and/or affected by swapping
> I2C_WRITE and I2C_READ gpi calls.
> 

Submitted V3 with proper commit log.

>>
>> For only write operation or write followed by read operation,
>> existing software sequence is correct.
>>
>> for only read operation, TRE sequence need to be corrected.
>> Hence, we have changed the sequence to submit GO tre before DMA tre.
>>
>> Tested covering i2c read/write transfer on QCM6490 RB3 board.
> 
> Please read Documentation/process/submitting-patches.rst, understand
> it and write a proper commit message.
> 
>>
>> Signed-off-by: Viken Dadhaniya <quic_vdadhani@...cinc.com>
>> Fixes: commit d8703554f4de ("i2c: qcom-geni: Add support for GPI DMA")
> 
> As it was pointed out, this line shows ignorance of the mentioned file
> and of the existing community practices.
> 

Updated fixes tag in V3.

>> ---
>> v1 -> v2:
>> - Remove redundant check.
>> - update commit log.
>> - add fix tag.
>> ---
>> ---
>>   drivers/i2c/busses/i2c-qcom-geni.c | 14 +++++++-------
>>   1 file changed, 7 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/busses/i2c-qcom-geni.c
>> index 0d2e7171e3a6..da94df466e83 100644
>> --- a/drivers/i2c/busses/i2c-qcom-geni.c
>> +++ b/drivers/i2c/busses/i2c-qcom-geni.c
>> @@ -613,20 +613,20 @@ static int geni_i2c_gpi_xfer(struct geni_i2c_dev *gi2c, struct i2c_msg msgs[], i
>>
>>                  peripheral.addr = msgs[i].addr;
>>
>> +               ret =  geni_i2c_gpi(gi2c, &msgs[i], &config,
>> +                                   &tx_addr, &tx_buf, I2C_WRITE, gi2c->tx_c);
>> +               if (ret)
>> +                       goto err;
>> +
>>                  if (msgs[i].flags & I2C_M_RD) {
>>                          ret =  geni_i2c_gpi(gi2c, &msgs[i], &config,
>>                                              &rx_addr, &rx_buf, I2C_READ, gi2c->rx_c);
>>                          if (ret)
>>                                  goto err;
>> -               }
>> -
>> -               ret =  geni_i2c_gpi(gi2c, &msgs[i], &config,
>> -                                   &tx_addr, &tx_buf, I2C_WRITE, gi2c->tx_c);
>> -               if (ret)
>> -                       goto err;
>>
>> -               if (msgs[i].flags & I2C_M_RD)
>>                          dma_async_issue_pending(gi2c->rx_c);
>> +               }
>> +
>>                  dma_async_issue_pending(gi2c->tx_c);
>>
>>                  timeout = wait_for_completion_timeout(&gi2c->done, XFER_TIMEOUT);
>> --
>> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
>> of Code Aurora Forum, hosted by The Linux Foundation
>>
>>
> 
>