Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754473AbaDOUlu (ORCPT ); Tue, 15 Apr 2014 16:41:50 -0400 Received: from mx1.redhat.com ([209.132.183.28]:14525 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750979AbaDOUls (ORCPT ); Tue, 15 Apr 2014 16:41:48 -0400 Message-ID: <534D9981.4030607@redhat.com> Date: Tue, 15 Apr 2014 22:41:37 +0200 From: Hans de Goede User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 MIME-Version: 1.0 To: Julius Werner , Mathias Nyman CC: "Nyman, Mathias" , Greg Kroah-Hartman , "linux-usb@vger.kernel.org" , Sarah Sharp , LKML , Vincent Palatin , Luigi Semenzato Subject: Re: [PATCH] usb: xhci: Prefer endpoint context dequeue pointer over stopped_trb References: <1392959535-29654-1-git-send-email-jwerner@chromium.org> <20140228205358.GA5340@xanatos> <534D2899.3030503@linux.intel.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/