Messages in this thread | | | Subject | Re: [PATCH v9 4/5] xhci: mediatek: support MTK xHCI host controller | From | Daniel Thompson <> | Date | Thu, 8 Oct 2015 13:28:29 +0100 |
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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;
>> Anyhow with that looked at, and the caveat that I'm not much of USB >> expert, you're welcome to add my Reviewed-by: to v10. >> > > Thanks a lot
No worries.
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