Alexey Orishko <alexey.orishko@xxxxxxxxx> writes: > Based on NCM errata, NCM functional descriptor: if Bit 5 is set, then > device can (must) handle 8-byte form of Set/GetNtbInputSize. > If they set a flag, but don't support the feature, hm.. is it a > prototype device or > commercially available one? > > At least device must support Set request, but for GetNtbInputSize we > could happily > live without wNtbInMaxDatagrams (i.e. use 4 byte variant) on Linux. > Since we must anyway receive a complete NTB and making any number of skb > buffers from received NTB is not a problem at all. OK, I may have misunderstood you here. Quoting the errata text: <quote> If bit D5 is set in the bmNetworkCapabilities field of function’s NCM Functional Descriptor, the host may set wLength either to 4 or to 8. If wLength is 4, the function shall assume that wNtbInMaxDatagrams is to be set to zero. If wLength is 8, then the function shall use the provided value as the limit. The function shall return an error response (a STALL PID) if wLength is set to any other value. </quote> So the 4 byte variant is always supported and we might as well just use it unconditionally because we don't set, or need to set, the wNtbInMaxDatagrams. Is that right? It will simplify the code even more without any loss of functionality, except for the possibility of failing on some other buggy device not supporting the 4 byte variant... Bjørn -- 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
