linux-kernel - Re: [PATCH] i2c: designware: Get right data length

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Date:   Thu, 25 Feb 2021 22:06:59 +0800
From:   乱石 <zhangliguang@...ux.alibaba.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] i2c: designware: Get right data length

Hi,
在 2021/2/25 19:19, Andy Shevchenko 写道:
> On Thu, Feb 25, 2021 at 10:35:28AM +0800, Liguang Zhang wrote:
>> IC_DATA_CMD[11] indicates the first data byte received after the address
>> phase for receive transfer in Master receiver or Slave receiver mode,
>> this bit was set in some transfer flow. IC_DATA_CMD[7:0] contains the
>> data to be transmitted or received on the I2C bus, so we should use the
>> lower 8 bits to get the right data length.
> Thanks for the report and fix!
> My comments below.

Thanks for your comments. I will optimize my code follow your comments 
and send v2 revision.

Regards,

Liguang

>
>> Signed-off-by: Liguang Zhang <zhangliguang@...ux.alibaba.com>
>> ---
>>   drivers/i2c/busses/i2c-designware-master.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c
>> index d6425ad6e6a3..c3cf76f6c607 100644
>> --- a/drivers/i2c/busses/i2c-designware-master.c
>> +++ b/drivers/i2c/busses/i2c-designware-master.c
>> @@ -432,7 +432,7 @@ i2c_dw_read(struct dw_i2c_dev *dev)
>>   			regmap_read(dev->map, DW_IC_DATA_CMD, &tmp);
>>   			/* Ensure length byte is a valid value */
>>   			if (flags & I2C_M_RECV_LEN &&
>> -			    tmp <= I2C_SMBUS_BLOCK_MAX && tmp > 0) {
>> +			    (tmp & 0xff) <= I2C_SMBUS_BLOCK_MAX && tmp > 0) {
> Can we rather describe this as
>
> #define DW_IC_DATA_CMD_DAT   GENMASK(7, 0)
>
> in *.h file and...
>
> 			    (tmp & DW_IC_DATA_CMD_DAT) <= I2C_SMBUS_BLOCK_MAX && tmp > 0) {
> ...here?
>
>>   				len = i2c_dw_recv_len(dev, tmp);
>>   			}
>>   			*buf++ = tmp;
>> -- 
>> 2.19.1.6.gb485710b
>>