Re: [PATCH V3 4/5] i2c: ls2x: Add driver for Loongson-2K/LS7A I2C controller

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Tue, Nov 29, 2022 at 07:34:58PM +0800, Binbin Zhou wrote:
> 在 2022/11/28 21:24, Andy Shevchenko 写道:
> > On Mon, Nov 28, 2022 at 08:03:40PM +0800, Binbin Zhou wrote:
> > > 在 2022/11/25 18:41, Andy Shevchenko 写道:
> > > > On Fri, Nov 25, 2022 at 04:55:20PM +0800, Binbin Zhou wrote:

...

> > > > > +static int ls2x_i2c_start(struct i2c_adapter *adap, struct i2c_msg *msgs)
> > > > > +{
> > > > > +	struct ls2x_i2c_dev *dev = i2c_get_adapdata(adap);
> > > > > +	unsigned char addr = i2c_8bit_addr_from_msg(msgs);
> > > > > +
> > > > > +	reinit_completion(&dev->cmd_complete);
> > > > > +	addr |= (msgs->flags & I2C_M_RD) ? 1 : 0;
> > > > Why is this needed?
> > > In the ls2x I2C controller, the bit 0 of TXR indicates the read/write status
> > > when transferring the address.
> > Yes, I understand this. I don't understand why do you need this twice.
> 
> Are you saying that the "is_read" variable in ls2x_i2c_xfer_one() already
> indicates the read/write state of data transfer?
> 
> I just didn't think it was necessary to take "is_read" as an argument to
> ls2x_i2c_start() at the time, since we could get it from "msg".

Have you checked what i2c_8bit_addr_from_msg() is doing?

-- 
With Best Regards,
Andy Shevchenko