On Thu, Apr 10, 2014 at 07:08:22PM +0000, Ebright, Dave wrote: > Hi Peter, > > > > I’m not sure what mailing list to post this to, but maybe you know… Linux usb mail list is the best place to ask linux usb questions. > > > > I am looking at the i.MX51 USB device functionality for a project I am > working on and in the DCCPARAMS register (read only) there is the DEN > field which defines the number of endpoints built into the device > controller. For the i.MX51 when the register is read the DEN is set to > 8. Valid values for this field are 0-16. My first question is do you > know of any way of increasing this value? I don’t believe it can be based > on the following from the i.MX51 reference manual: > > > > “The ARC USB-HS OTG High-Speed USB On-The-Go device controller hardware > supports up to the USB > > 2.0 maximum of 32 endpoint specified numbers. Each additional endpoint > beyond the required endpoint > > position adds additional hardware logic. The maximum number of endpoint > numbers available to the DCD > > is configured at hardware synthesis timer. After synthesis, the DCD can > enable, disable and configure > > endpoint type up to the maximum selected during synthesis.” > > > > Does synthesis mean when the processor chip is created or does it mean > when the chip first starts up HW senses what the value should be? When the IC guys begin to integrate usb ip, the endpoint number can be changed, but once the chip has finished, this number can't be changed. > > > > Any idea if it would work to just over-ride the ci->hw_ep_map value set in > hw_device_init()? Not sure what the synthesis does? The ChipIdea > register set is still the same, but I assume the functionality is somehow > limited in the core? Yes, this value is fixed for certain chipidea IP usb controller. > > > > If the number of endpoints cannot be increased, would it be possible to > map an unused endpoint number to a higher endpoint number. For example > let’s say I want my device to use endpoint 9, but endpoint 9 is not > defined due to the DEN value of 8. Endpoint 7 exists and is not being > used. Would it be possible to customize the chipidea drivers to map > endpoint 9 to use endpoint 7 for a custom application or does the USB OTG > chipidea core perform HW controlled endpoint addressing (HW looks at > endpoint and sends data to the appropriate endpoint queue independent of > the driver)? > > If endpoint number is 8, for chipidea udc driver, the ci_hw_ep[0..7] is the physical RX endpoint 0-7, , the name is "ep[0..7]out", the ci_hw_ep[8..15] is the physical TX endpoint 0-7, the name is "ep[0..7]in". What's the reason you want to customize endpoint number? Currently, it will allocate the smallest un-used endpoint number for application. -- Best Regards, Peter Chen -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
