Hi On Mon, 2015-08-17 at 18:07 +0300, Mathias Nyman wrote: > Hi > > On 07.08.2015 15:30, Chunfeng Yun wrote: > > MTK xhci host controller defines some extra SW scheduling > > parameters for HW to minimize the scheduling effort for > > synchronous and interrupt endpoints. The parameters are > > put into reseved DWs of slot context and endpoint context > > > > > > ... > > > + * The TD size is the number of max packet sized packets remaining in the > > TD > > + * (including this TRB), right shifted by 10. > > + * It must fit in bits 21:17, so it can't be bigger than 31. > > + */ > > +u32 xhci_mtk_td_remainder_quirk(unsigned int td_running_total, > > + unsigned trb_buffer_length, struct urb *urb) > > +{ > > + u32 max = 31; > > + int remainder, td_packet_count, packet_transferred; > > + unsigned int td_transfer_size = urb->transfer_buffer_length; > > + unsigned int maxp; > > + > > + maxp = GET_MAX_PACKET(usb_endpoint_maxp(&urb->ep->desc)); > > + > > + /* 0 for the last TRB */ > > + if (td_running_total + trb_buffer_length == td_transfer_size) > > + return 0; > > + > > + packet_transferred = td_running_total / maxp; > > + td_packet_count = DIV_ROUND_UP(td_transfer_size, maxp); > > + remainder = td_packet_count - packet_transferred; > > + > > + if (remainder > max) > > + return max << 17; > > + else > > + return remainder << 17; > > +} > > I started looking at this xhci_mtk_td_remainder() function, one > of the places this patch touches the existing xhci code. > > The remainder functions in xhci are already bit too messy, and > adding one more function which does almost the same thing makes > it even messier. > > For example queuing a bulk transfer will end up like this: > > > /* Set the TRB length, TD size, and interrupter fields. */ > > if (xhci->hci_version < 0x100) { > > - remainder = xhci_td_remainder( > > + if (xhci->quirks & XHCI_MTK_HOST) { > > + remainder = xhci_mtk_td_remainder_quirk( > > + running_total, trb_buff_len, urb); > > + } else { > > + remainder = xhci_td_remainder( > > urb->transfer_buffer_length - > > running_total); > > + } > > } else { > > remainder = xhci_v1_0_td_remainder(running_total, > > trb_buff_len, total_packet_count, urb, > > and similar for isoc and control transfers. > > I'll see if I can simplify the existing remainder calculations into one > function, then it should > be enough to just add something like this into it: > > if (xhci->quirks & XHCI_MTK_HOST) > trb_buff_len = 0; > > This way we can skip all the extra hassle that comes with a new exported > quirk function > > Is the Mediatek xhci really a xHCI 0.96 or older controller? (hci_version < > 0x100) > Not a xHCI 1.0 or 1.1 ? > It is xHCI 0.96, but add some feature of xHCI 1.0
Thanks a lot > -Mathias -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/