i2c: designware: Get right data length
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Message ID 20210225023528.121135-1-zhangliguang@linux.alibaba.com
State New, archived
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  • i2c: designware: Get right data length
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Commit Message

Liguang Zhang Feb. 25, 2021, 2:35 a.m. UTC
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.

Signed-off-by: Liguang Zhang <zhangliguang@linux.alibaba.com>
---
 drivers/i2c/busses/i2c-designware-master.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Andy Shevchenko Feb. 25, 2021, 11:19 a.m. UTC | #1
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.

> Signed-off-by: Liguang Zhang <zhangliguang@linux.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
>
Liguang Zhang Feb. 25, 2021, 2:06 p.m. UTC | #2
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@linux.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
>>

Patch
diff mbox series

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) {
 				len = i2c_dw_recv_len(dev, tmp);
 			}
 			*buf++ = tmp;