Re: [PATCH v13 2/3] i2c: aspeed: support AST2600 i2c new register mode driver

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

On Fri, Aug 23, 2024 at 06:23:54AM +0000, Ryan Chen wrote:
> > On Thu, Aug 22, 2024 at 02:24:26AM +0000, Ryan Chen wrote:
> > > > On Wed, Aug 21, 2024 at 06:43:01AM +0000, Ryan Chen wrote:
> > > > > > On Mon, Aug 19, 2024 at 05:28:49PM +0800, Ryan Chen wrote:

...

> > > > > > > +	if (i2c_bus->mode == BUFF_MODE) {
> > > > > > > +		i2c_bus->buf_base =
> > > > > > devm_platform_get_and_ioremap_resource(pdev, 1, &res);
> > > > > > > +		if (!IS_ERR_OR_NULL(i2c_bus->buf_base))
> > > > > > > +			i2c_bus->buf_size = resource_size(res) / 2;
> > > > > > > +		else
> > > > > > > +			i2c_bus->mode = BYTE_MODE;
> > > > > >
> > > > > > What's wrong with positive conditional? And is it even possible
> > > > > > to have NULL here?
> > > > > >
> > > > > Yes, if dtsi fill not following yaml example have reg 1, that will
> > > > > failure at buffer
> > > > mode.
> > > > > And I can swith to byte mode.
> > > > >
> > > > > reg = <0x80 0x80>, <0xc00 0x20>;
> > > >
> > > > I was asking about if (!IS_ERR_OR_NULL(...)) line:
> > > > 1) Why 'if (!foo) {} else {}' instead of 'if (foo) {} else {}'?
> > > I will update to following.
> > > 		if (IS_ERR(i2c_bus->buf_base))
> > > 			i2c_bus->mode = BYTE_MODE;
> > > 		else
> > > 			i2c_bus->buf_size = resource_size(res) / 2;
> > >
> > > > 2) Why _NULL?
> > > 	If dtsi file is claim only 1 reg offset. reg = <0x80 0x80>; that will goto byte
> > mode.
> > > 	reg = <0x80 0x80>, <0xc00 0x20>; can support buffer mode.
> > > 	due to 2nd is buffer register offset.
> > 
> > I have asked why IS_ERR_OR_NULL() and not IS_ERR().
> > 
> OH, I will doing by this.
> 		if (IS_ERR_OR_NULL(i2c_bus->buf_base))

The question about _NULL remains unanswered...

> 			i2c_bus->mode = BYTE_MODE;
> 		else
> 			i2c_bus->buf_size = resource_size(res) / 2;

-- 
With Best Regards,
Andy Shevchenko