Re: [PATCH v6 2/4] i2c: npcm: Modify the client address assignment

Tyrone Ting
2024-10-11T13:44:54Z

Hi Andy:

Thank you for your comments.

Andy Shevchenko <andriy.shevchenko@linux.intel.com> 於 2024年10月11日 週五 下午7:00寫道：
>
> On Fri, Oct 11, 2024 at 01:52:29PM +0800, Tyrone Ting wrote:
> > From: Tyrone Ting <kfting@nuvoton.com>
> >
> > Store the client address earlier since it might get called in
> > the i2c_recover_bus() logic flow at the early stage of
> > npcm_i2c_master_xfer().
>
> ...
>
> > + /*
> > + * Previously, the address was stored w/o left-shift by one bit and
> > + * with that shift in the following call to npcm_i2c_master_start_xmit().
> > + *
> > + * Since there are cases that the i2c_recover_bus() gets called at the
> > + * early stage of npcm_i2c_master_xfer(), the address is stored with
> > + * the shift and used in the i2c_recover_bus().
> > + *
> > + * The address is stored from bit 1 to bit 7 in the register for
> > + * sending the i2c address later so it's left-shifted by 1 bit.
> > + */
>
> I would rephrase it a bit like
>
> /*
> * Previously, the 7-bit address was stored and being converted to
> * the address of event in the following call to npcm_i2c_master_start_xmit().
> *
> * Since there are cases that the i2c_recover_bus() gets called at the
> * early stage of npcm_i2c_master_xfer(), the address of event is stored
> * and then used in the i2c_recover_bus().
> */
>
> (E.g., the last paragraph just describes 101 about I2C 7-bit addresses usage
> and may be dropped completely.)
>

Understood. I'll modify the comments and remove the last paragraph.

> > + bus->dest_addr = i2c_8bit_addr_from_msg(msg0);
>
> ...
>
> > + /*
> > + * Since the transfer might be a read operation, remove the I2C_M_RD flag
> > + * from the bus->dest_addr for the i2c_recover_bus() call later.
> > + *
> > + * The i2c_recover_bus() uses the address in a write direction to recover
> > + * the i2c bus if some error condition occurs.
> > + */
>
> > + if (bus->dest_addr & I2C_M_RD)
>
> Redundant.
>

Just to double check. Is the code "if (bus->dest_addr & I2C_M_RD)" redundant?

> > + bus->dest_addr &= ~I2C_M_RD;
>
> --
> With Best Regards,
> Andy Shevchenko
>
>

Thank you again.

Regards,
Tyrone