On 1/23/2017 2:10 PM, Alan Stern wrote: > 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. > Yes that's correct. The general fix should take all that into account so that any combination of NUM_EPS and NUM_IN_EPS will work fine. However it must also account for FPGA configs where each HW endpoint has a fixed number/direction, which the current code is compatible with. John -- 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
