[U-Boot] [PATCH v2 12/17] usb: Add support for txfifo threshold

[Simon Glass]

Hi Stephen,

On Tue, Dec 6, 2011 at 10:58 AM, Stephen Warren <swarren at nvidia.com> wrote:
> Simon Glass wrote at Monday, December 05, 2011 7:03 PM:
>> On Mon, Dec 5, 2011 at 3:32 PM, Stephen Warren <swarren at nvidia.com> wrote:
>> > On 12/02/2011 07:11 PM, Simon Glass wrote:
>> >> CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the txfilltuning
>> >> field in the EHCI controller on reset.
>> >
>> >> diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
>> >> index 3d0ad0c..cc00ce4 100644
>> >> --- a/drivers/usb/host/ehci.h
>> >> +++ b/drivers/usb/host/ehci.h
>> >> @@ -80,7 +80,11 @@ struct ehci_hcor {
>> >>       uint32_t or_ctrldssegment;
>> >>       uint32_t or_periodiclistbase;
>> >>       uint32_t or_asynclistaddr;
>> >> -     uint32_t _reserved_[9];
>> >> +     uint32_t _reserved_0_;
>> >
>> > Why not remove _reserved_0_ ...
>> >
>> >> +     uint32_t or_burstsize;
>> >> +     uint32_t or_txfilltuning;
>> >> +#define TXFIFO_THRESH(p)             ((p & 0x3f) << 16)
>> >> +     uint32_t _reserved_1_[6];
>> >
>> > ... and make _reserved_1_ 1 element bigger and keep it named _reserved_?
>> > The result would be a little simpler.
>>
>> Sorry I'm a bit stuck with that one. I have:
>>
>>       uint32_t or_asynclistaddr;
>>       uint32_t _reserved_0_;
>>       uint32_t or_burstsize;
>>       uint32_t or_txfilltuning;
>>       uint32_t _reserved_1_[6];
>>       uint32_t or_configflag;
>>
>> How can I remove _reserved_0_? I would need to replace it with
>> something, as need or_burstsize to stay where it is. Can you please
>> explain a little more?
>
> Oh right, this is a HW structure, so the layout is fixed? In which case
> the patch is fine. I wonder why all the fields weren't just defined from
> the start rather than being marked "reserved" though; perhaps it'd be
> best to update the code to completely flesh out the HW description at
> some point. Not necessarily in this patch though.

Yes that's right. Will leave this patch as is and resend series.

There are two sides to this: some people will say they want everything
in there in case they want to access a particular field later. Others
will say that it adds confusion and dead code. I think I'll sit on the
fence.

Regards,
Simon

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