Messages in this thread | | | Date | Thu, 08 Oct 2015 16:05:00 +0300 | From | Mathias Nyman <> | Subject | Re: [PATCH v9 4/5] xhci: mediatek: support MTK xHCI host controller |
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On 08.10.2015 15:28, Daniel Thompson wrote: > On 08/10/15 13:05, chunfeng yun wrote: >> Hi, >> On Thu, 2015-10-01 at 12:44 +0100, Daniel Thompson wrote: >>> On 29/09/15 04:01, Chunfeng Yun wrote: >>>> There some vendor quirks for MTK xhci host controller: >>>> 1. It 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. >>>> 2. Its IMODI unit for Interrupter Moderation register is >>>> 8 times as much as that defined in xHCI spec. >>>> 3. Its TDS in Normal TRB defines a number of packets that >>>> remains to be transferred for a TD after processing all >>>> Max packets in all previous TRBs. >>>> >>>> Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com> >>> >>> I've done some basic soak tests, both with a directly attached USB3 HDD >>> and, given the extra code to manage isochronous xfer, also with a hub, >>> disc and two audio interfaces. >>> >>> Tested-by: Daniel Thompson <daniel.thompson@linaro.org> >>> >>> >>>> diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c >>>> index 57f40a1..243f696 100644 >>>> --- a/drivers/usb/host/xhci-ring.c >>>> +++ b/drivers/usb/host/xhci-ring.c >>>> @@ -68,6 +68,7 @@ >>>> #include <linux/slab.h> >>>> #include "xhci.h" >>>> #include "xhci-trace.h" >>>> +#include "xhci-mtk.h" >>>> >>>> /* >>>> * Returns zero if the TRB isn't in this segment, otherwise it returns the DMA >>>> @@ -3044,18 +3045,27 @@ static u32 xhci_td_remainder(struct xhci_hcd *xhci, int transferred, >>>> struct urb *urb, unsigned int num_trbs_left) >>>> { >>>> u32 maxp, total_packet_count; >>>> + u32 skip_current_trb = 0; >>> >>> A bit of a nitpick but why do we need skip_current_trb? Testing >>> (xhci->quirks & XHCI_MTK_HOST) twice would make what the code does, and >>> why, more obvious. >>> >> I am not sure which way it is better, so add variable of >> skip_current_trb to reduce test times. > > I can't imagine either approach impacts performance. However introducing skip_current_trb makes the flow of the branches harder to follow. > > The first branch was a version check and can remain so; we only need to do something special with the quirks because the MTK controller is 0.97 but with a few bits added: > > /* MTK xHCI is mostly 0.97 but contains some features from 1.0 */ > if (xhci->hci_version < 0x100 && !(xhci->quirks & XHCI_MTK_HOST)) > return ... > > Setting trb_buff_len to zero is accommodating a quirk and this is clearer when we have: > > /* for MTK xHCI, TD size doesn't include this TRB */ > if (xhci->quirks & XHCI_MTK_HOST) > trb_buff_len = 0;
Both will work, but I'd prefer this solution as well.
-Mathias
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