On Mon, 23 Jan 2017, John Youn wrote:
> On 1/22/2017 5:29 PM, Bryan O'Donoghue wrote:
> > - DWC_USB3_NUM indicates the number of Device mode single directional
> > endpoints, including OUT and IN endpoint 0.
> >
> > - DWC_USB3_NUM_IN_EPS indicates the maximum number of Device mode IN
> > endpoints active at any time, including control endpoint 0.
> >
> > It's possible to configure RTL such that DWC_USB3_NUM_EPS is equal to
> > DWC_USB3_NUM_IN_EPS.
> >
> > dwc3-core calculates the number of OUT endpoints as DWC_USB3_NUM minus
> > DWC_USB3_NUM_IN_EPS. If RTL has been configured with DWC_USB3_NUM_IN_EPS
> > equal to DWC_USB3_NUM then dwc3-core will calculate the number of OUT
> > endpoints as zero.
> >
> > For example a from dwc3_core_num_eps() shows:
> > [ 1.565000] /usb0@f01d0000: found 8 IN and 0 OUT endpoints
> >
> > This patch works around this case by detecting when DWC_USB3_NUM_EPS is
> > equal to DWC3_USB3_NUM_IN_EPS and over-rides the calculation of the number
>
> What if NUM_IN_EPS=7 and NUM_EPS=8? You will still have a problem.
>
> It's possible to fix this for the general case rather than for this
> specific case.
What is the reason for computing NUM_OUT_EPS in the first place?
Isn't it true that any endpoint can be used as an OUT endpoint?
So the real restrictions on a configuration are:
number of IN endpoints <= NUM_IN_EPS, and
number of IN endpoints + number of OUT endpoints <= NUM_EPS,
where ep0 must be counted twice, as both an IN and an OUT endpoint.
The value of NUM_OUT_EPS isn't used and shouldn't matter.
Alan Stern
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