Messages in this thread | | | Date | Tue, 15 Apr 2014 22:41:37 +0200 | From | Hans de Goede <> | Subject | Re: [PATCH] usb: xhci: Prefer endpoint context dequeue pointer over stopped_trb |
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Hi,
On 04/15/2014 09:42 PM, Julius Werner wrote: > +hdegoede > >> I tried to apply this patch on top of 3.15-rc1, but it fails because of the >> streams support added to xhci_find_new_dequeue_state() >> >> After some manual editing the interesting parts of >> xhci_find_new_dequeue_state() looks like this: >> >> @@ -577,46 +568,57 @@ void xhci_find_new_dequeue_state(struct xhci_hcd >> *xhci, >> if (ep->ep_state & EP_HAS_STREAMS) { >> struct xhci_stream_ctx *ctx = >> &ep->stream_info->stream_ctx_array[stream_id]; >> - state->new_cycle_state = 0x1 & >> le64_to_cpu(ctx->stream_ring); >> + hw_dequeue = le64_to_cpu(ctx->stream_ring); >> } else { >> struct xhci_ep_ctx *ep_ctx >> >> = xhci_get_ep_ctx(xhci, dev->out_ctx, ep_index); >> - state->new_cycle_state = 0x1 & le64_to_cpu(ep_ctx->deq); >> + hw_dequeue = le64_to_cpu(ep_ctx->deq); >> } >> >> + /* Find virtual address and segment of hardware dequeue pointer */ >> >> + state->new_deq_seg = ep_ring->deq_seg; >> + state->new_deq_ptr = ep_ring->dequeue; >> + while (xhci_trb_virt_to_dma(state->new_deq_seg, state->new_deq_ptr) >> + != (dma_addr_t)(hw_dequeue & ~0x1)) { >> + next_trb(xhci, ep_ring, &state->new_deq_seg, >> + &state->new_deq_ptr); >> + if (state->new_deq_ptr == ep_ring->dequeue) { >> + WARN_ON(1); >> + return; >> + } >> + } >> >> Also the comparison of the dequeue pointers, using (hw_dequeue & ~0x1) might >> have some troubles with streams. Endpoint context TR dequeue pointer LO >> field has bits 3:1 reserved (probably zero) but stream context uses those >> bits. Would it make sense to use (hw_dequeue & ~0xf) here instead? > > Ah, yes, looks like that patch wasn't in Linus' tree yet back when I > wrote this. I think your merge looks pretty good... just use > (hw_dequeue & ~0xf) instead of (hw_dequeue & ~0x1) to get the pointer > as you said, and this should work fine. > >> But I'm still concerned about the dequeue pointer in the streams case. >> streams may be nested, we might be pointing at another stream context >> instead of the dequeue pointer.
Since I've not followed the entire discussion previously to this I cannot really provide any useful feedback on this patch. Other then 2 remarks:
1) We don't use nested streams, so no need to worry about those 2) You're right that for streams to get the dequeue address you need to mask with ~0xf
Regards,
Hans
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