Re: [PATCH 4/9] i2c: brcmstb: enable ACK condition

[Jaedon Shin <jaedon.shin@gmail.com>]

Hi Kamal,

On Dec 1, 2015, at 12:37 AM, Wolfram Sang <wsa@the-dreams.de> wrote:
> 
> On Wed, Oct 21, 2015 at 11:36:56AM +0900, Jaedon Shin wrote:
>> Removes the condition of a message with under 32 bytes in length. The
>> messages that do not require an ACK are I2C_M_IGNORE_NAK flag.
> 
> Makes me wonder why it worked before? Kamal?
> 
>> 
>> Signed-off-by: Jaedon Shin <jaedon.shin@gmail.com>
>> ---
>> drivers/i2c/busses/i2c-brcmstb.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>> 
>> diff --git a/drivers/i2c/busses/i2c-brcmstb.c b/drivers/i2c/busses/i2c-brcmstb.c
>> index 2d7d155029dc..53eb8b0c9bad 100644
>> --- a/drivers/i2c/busses/i2c-brcmstb.c
>> +++ b/drivers/i2c/busses/i2c-brcmstb.c
>> @@ -330,7 +330,7 @@ static int brcmstb_i2c_xfer_bsc_data(struct brcmstb_i2c_dev *dev,
>> 	int no_ack = pmsg->flags & I2C_M_IGNORE_NAK;
>> 
>> 	/* see if the transaction needs to check NACK conditions */
>> -	if (no_ack || len <= N_DATA_BYTES) {

Could you please explain why have NOACK with smaller transfer size? I don't find any 
reason about NOACK when smaller size, and the driver always operates NOACK by "len <= xfersz".

brcmstb_i2c_xfer(...)
{
	int xfersz = brcmstb_i2c_get_xfersz(dev);
	...
	bytes_to_xfer = min(len, xfersz);
	...
	brcmstb_i2c_xfer_bsc_data(..., bytes_to_xfer, ...);
	...

I have a plan for v2 that has for BMIPS_GENERIC and this patch with the latest driver.

Thanks!
--
Jaedon

>> +	if (no_ack) {
>> 		cmd = (pmsg->flags & I2C_M_RD) ? CMD_RD_NOACK
>> 			: CMD_WR_NOACK;
>> 		pi2creg->ctlhi_reg |= BSC_CTLHI_REG_IGNORE_ACK_MASK;
>> -- 
>> 2.6.1
>>