[U-Boot] [PATCH v4 0/3] AM335x: Add USB support in u-boot.

[Marek Vasut]

Dear Harman Sohanpal,

> On Sat, Jun 30, 2012 at 6:15 AM, Marek Vasut <marex at denx.de> wrote:
> > Dear Harman Sohanpal,
> > 
> >> These patches add USB support in u-boot for AM335x.
> >> The support for host or device is selected
> >> depending on the config selected from boards.cfg file.
> >> Host mode is selected for USB1 and device mode is
> >> selected for USB0.
> >> Base addresses are selected accordingly.
> >> 
> >> Gene Zarkhin (1):
> >>   AM335x : Add USB support for AM335x in u-boot
> >> 
> >> Harman Sohanpal (2):
> >>   AM335x : Configs to add USB host support.
> >>   musb_udc : Fix compile warning.
> > 
> > Dumb question ... but, can this not be made part of am35x USB ?
> 
> Hi Marek,
> Well this can always be made part of am35x.c.
> But there would be a lot of changes required in the file.

Why? They use different IP block or something?

> And also I believe it would not make much sense.
> It would require ifdefs at a lot of places.
> Best example I can give to support what i said is
>  that the control register
> is at an offset of 4 in am35x and 14 in am335x.

So what, define two sets of register structures and pass them according to CPU 
ID.

> I am sure adding an ifdef at that place would not seem
> good to you to change address from 4 to 14 acc to platform.

well ...
struct regs_a {
	uint32_t padding[?];
	uint32_t reg;
...
};

struct regs_b {
	uint32_t reg;
...
};

Create IO accessors ... like ... my_usb_writel() and my_usb_readl() to read and 
write the registers. And those accessors will cover the differences. Or is there 
more?

> Is there much pain to add these 2 files?

Yes, duplication of code is always bad.

> In my opinion we must need to have a separate file for this.

Why? If it's only about the registers, won't the approach above work?

> This is as per my understanding.
> It could also cause confusions to some due to name. maybe :)

I'm no omap guru, Tom is. Tom?

> Kindly give your thoughts.

Oh my brain is spinning from this :-)

> In case still some changes are required, we can think upon it :)

I'm really glad to hear that, let's do our best to find the best possible 
solution :-)

> Thanks,
> Harman


Best regards,
Marek Vasut