[PATCH v3 1/3] usb: fsl-mxc-udc: replace cpu_is_xxx() with platform_device_id

[Felipe Balbi]

On Mon, Jan 14, 2013 at 12:03:04PM +0100, Marc Kleine-Budde wrote:
> On 01/14/2013 11:53 AM, Felipe Balbi wrote:
> > Hi,
> > 
> > On Mon, Jan 14, 2013 at 11:50:41AM +0100, Marc Kleine-Budde wrote:
> >> On 01/14/2013 11:39 AM, Felipe Balbi wrote:
> >>> On Mon, Jan 14, 2013 at 11:34:05AM +0100, Marc Kleine-Budde wrote:
> >>>> On 01/14/2013 11:24 AM, Felipe Balbi wrote:
> >>>>> On Mon, Jan 14, 2013 at 11:18:53AM +0100, Marc Kleine-Budde wrote:
> >>>>>> On 01/14/2013 11:16 AM, Felipe Balbi wrote:
> >>>>>>> Hi,
> >>>>>>>
> >>>>>>> On Mon, Jan 14, 2013 at 06:12:39PM +0800, Peter Chen wrote:
> >>>>>>>> @@ -2756,22 +2753,41 @@ static int fsl_udc_otg_resume(struct device *dev)
> >>>>>>>>  
> >>>>>>>>  	return fsl_udc_resume(NULL);
> >>>>>>>>  }
> >>>>>>>> -
> >>>>>>>>  /*-------------------------------------------------------------------------
> >>>>>>>>  	Register entry point for the peripheral controller driver
> >>>>>>>>  --------------------------------------------------------------------------*/
> >>>>>>>> -
> >>>>>>>> +static const struct platform_device_id fsl_udc_devtype[] = {
> >>>>>>>> +	{
> >>>>>>>> +		.name = "imx-udc-mx25",
> >>>>>>>> +		.driver_data = IMX25_UDC,
> >>>>>>>> +	}, {
> >>>>>>>> +		.name = "imx-udc-mx27",
> >>>>>>>> +		.driver_data = IMX27_UDC,
> >>>>>>>> +	}, {
> >>>>>>>> +		.name = "imx-udc-mx31",
> >>>>>>>> +		.driver_data = IMX31_UDC,
> >>>>>>>> +	}, {
> >>>>>>>> +		.name = "imx-udc-mx35",
> >>>>>>>> +		.driver_data = IMX35_UDC,
> >>>>>>>> +	}, {
> >>>>>>>> +		.name = "imx-udc-mx51",
> >>>>>>>> +		.driver_data = IMX51_UDC,
> >>>>>>>> +	}
> >>>>>>>> +};
> >>>>>>>
> >>>>>>> I wonder if your driver-data is actually needed since you can use string
> >>>>>>> comparisson to achieve the exact same outcome.
> >>>>>>
> >>>>>> Why use a string compare, if the kernel infrastructure already does this
> >>>>>> for you?
> >>>>>
> >>>>> what do you mean ? What kernel infrastructure is doing waht for me ?
> >>>>
> >>>> The kernel infrastructure is doing the string compare for you to match
> >>>> the device against the driver (via platform_device_id->name). You get
> >>>> the a pointer to the driver_data for free. So you don't need any string
> >>>> compare in the driver later.
> >>>
> >>> but current driver data is just duplicating name with an integer, it's
> >>> pretty useless driver data.
> >>
> >> I don't think so - another argument:
> >> Less code. As struct platform_device_id is a static array the space is
> >> allocated anyway. So it doesn't make any difference if driver_data is
> >> NULL or not. Later you just need to make an integer comparison instead
> >> of a call to a strcmp(), if you have a switch/case and IMX*_UDC is an
> >> enum, the compiler will warn you if you've missed an IMX variant.
> > 
> > fair enough, but then don't create a different enum value for each imx
> > instance if they're mostly the same. Differentiate only what's actually
> > different.
> 
> Usually there isn't any Changelog between IP cores used in the different
> fsl processors (at least available outside of fsl), that makes it quite
> difficult to say if something found on one imx is really the same as on
> the other one. And they (usually) don't provide any versioning
> information in a register or the documentation.
> 
> just my 2¢

$SUBJECT is trying to differentiate a single feature (or maybe two) to
replace cpu_is_xxx(), then expose that on driver_data without creating
one enum value for each release from fsl.

-- 
balbi
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