On Friday 07 June 2013 10:42:28 Alexey Brodkin wrote:
> On 06/07/2013 12:47 PM, Arnd Bergmann wrote:
> > I wonder if it would be better to name the directory "synopsys" or
> > "designware" rather than "arc" now. Is there a chance that the same
> > controller is used on non-arc CPUs?
>
> The thing is - "arc_emac" is a custom ARC's (that was implemented before
> acquisition of ARC by Synopsys) IP (it's not an IC - just a part of CPU)
> Ethernet controller that only exists in some legacy FPGA boards we
> (ex-ARC and our customers) still use a lot in development process.
>
> Synopsys itself doesn't actively sell this device so there's no point in
> putting ARC EMAC into Synopsys folder.
>
> And indeed we don't expect this device to be used with non-ARC CPU's.
>
> I didn't add dependency on ARC in Kconfig just because I wanted to leave
> an ability to build this driver on x86 machine. I thought this is
> important requirement - allow anybody to at least build this driver to
> make sure it builds and doesn't cause tons of warnings to appear.
>
> If it's totally fine to add dependency on ARC - then it would be even
> easier for me - refer to the next block of comments.
No, I think making it generally available for all architectures is better.
> >> +static int arc_emac_probe(struct platform_device *pdev)
> >> +{
> >> + struct net_device *net_dev;
> >> + struct arc_emac_priv *priv;
> >> + int err;
> >> + unsigned int clock_frequency;
> >> + unsigned int id;
> >> + struct resource res_regs;
> >> +#ifdef CONFIG_OF_IRQ
> >> + struct resource res_irq;
> >> +#endif
> >> + const char *mac_addr = NULL;
> >
> > Please remove the #ifdef here. The driver does not work without this
> > anyway, so better make it 'depend on OF_IRQ' in Kconfig.
>
> As stated above I wanted to make it possible to compile on x86.
> And for this I needed to:
> 1. Add explicit mentions of "linux/platform_device.h" because with
> existence of OF "linux/of_platform.h" has "linux/platform_device.h"
> included internally.
> 2. Enclose "of_irq_to_resource" and "of_get_mac_address" in ifdefs
> because neither of them has a stub for non-OF situation.
But you can enable CONFIG_OF on x86. An allmodconfig build should
still enable this driver. The #ifdefs are generally considered ugly,
and there is no point adding them when the driver clearly wouldn't
work on any architecture without them even if that hardware was
available.
> So if I may depend on ARC then I'm sure OF is selected and no need to worry.
> Otherwise do I need to add stubs for "of_irq_to_resource" and
> "of_get_mac_address" somewhere in "of/of_xxx.h"?
We are currently discussing those changes to the header files elsewhere.
I think with a dependency on CONFIG_OF_IRQ and other symbols you need,
you get the best compromise of the various requirements.
Arnd
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