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From: Douglas Anderson <dianders@chromium.org>
To: John Youn <John.Youn@synopsys.com>,
	balbi@ti.com, kever.yang@rock-chips.com
Cc: william.wu@rock-chips.com, huangtao@rock-chips.com,
	heiko@sntech.de, stefan.wahren@i2se.com,
	linux-rockchip@lists.infradead.org,
	linux-rpi-kernel@lists.infradead.org,
	Julius Werner <jwerner@chromium.org>,
	gregory.herrero@intel.com, yousaf.kaukab@intel.com,
	dinguyen@opensource.altera.com, stern@rowland.harvard.edu,
	ming.lei@canonical.com, Douglas Anderson <dianders@chromium.org>,
	johnyoun@synopsys.com, gregkh@linuxfoundation.org,
	linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v6 20/22] usb: dwc2: host: Properly set even/odd frame
Date: Thu, 28 Jan 2016 18:20:11 -0800	[thread overview]
Message-ID: <1454034013-24657-21-git-send-email-dianders@chromium.org> (raw)
In-Reply-To: <1454034013-24657-1-git-send-email-dianders@chromium.org>

When setting up ISO and INT transfers dwc2 needs to specify whether the
transfer is for an even or an odd frame (or microframe if the controller
is running in high speed mode).

The controller appears to use this as a simple way to figure out if a
transfer should happen right away (in the current microframe) or should
happen at the start of the next microframe.  Said another way:

- If you set "odd" and the current frame number is odd it appears that
  the controller will try to transfer right away.  Same thing if you set
  "even" and the current frame number is even.
- If the oddness you set and the oddness of the frame number are
  _different_, the transfer will be delayed until the frame number
  changes.

As I understand it, the above technique allows you to plan ahead of time
where possible by always working on the next frame.  ...but it still
allows you to properly respond immediately to things that happened in
the previous frame.

The old dwc2_hc_set_even_odd_frame() didn't really handle this concept.
It always looked at the frame number and setup the transfer to happen in
the next frame.  In some cases that meant that certain transactions
would be transferred in the wrong frame.

We'll try our best to set the even / odd to do the transfer in the
scheduled frame.  If that fails then we'll do an ugly "schedule ASAP".
We'll also modify the scheduler code to handle this and not try to
schedule a second transfer for the same frame.

Note that this change relies on the work to redo the microframe
scheduler.  It can work atop ("usb: dwc2: host: Manage frame nums better
in scheduler") but it works even better after ("usb: dwc2: host: Totally
redo the microframe scheduler").

With this change my stressful USB test (USB webcam + USB audio +
keyboards) has less audio crackling than before.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
---
Changes in v6:
- Add Heiko's Tested-by.
- Add Stefan's Tested-by.

Changes in v5: None
Changes in v4:
- Properly set even/odd frame new for v4.

Changes in v3: None
Changes in v2: None

 drivers/usb/dwc2/core.c      | 92 +++++++++++++++++++++++++++++++++++++++++++-
 drivers/usb/dwc2/hcd_queue.c | 11 +++++-
 2 files changed, 100 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/dwc2/core.c b/drivers/usb/dwc2/core.c
index a5db20f12ee4..c143f26bd9d9 100644
--- a/drivers/usb/dwc2/core.c
+++ b/drivers/usb/dwc2/core.c
@@ -1703,9 +1703,97 @@ static void dwc2_hc_set_even_odd_frame(struct dwc2_hsotg *hsotg,
 {
 	if (chan->ep_type == USB_ENDPOINT_XFER_INT ||
 	    chan->ep_type == USB_ENDPOINT_XFER_ISOC) {
-		/* 1 if _next_ frame is odd, 0 if it's even */
-		if (!(dwc2_hcd_get_frame_number(hsotg) & 0x1))
+		int host_speed;
+		int xfer_ns;
+		int xfer_us;
+		int bytes_in_fifo;
+		u16 fifo_space;
+		u16 frame_number;
+		u16 wire_frame;
+
+		/*
+		 * Try to figure out if we're an even or odd frame. If we set
+		 * even and the current frame number is even the the transfer
+		 * will happen immediately.  Similar if both are odd. If one is
+		 * even and the other is odd then the transfer will happen when
+		 * the frame number ticks.
+		 *
+		 * There's a bit of a balancing act to get this right.
+		 * Sometimes we may want to send data in the current frame (AK
+		 * right away).  We might want to do this if the frame number
+		 * _just_ ticked, but we might also want to do this in order
+		 * to continue a split transaction that happened late in a
+		 * microframe (so we didn't know to queue the next transfer
+		 * until the frame number had ticked).  The problem is that we
+		 * need a lot of knowledge to know if there's actually still
+		 * time to send things or if it would be better to wait until
+		 * the next frame.
+		 *
+		 * We can look at how much time is left in the current frame
+		 * and make a guess about whether we'll have time to transfer.
+		 * We'll do that.
+		 */
+
+		/* Get speed host is running at */
+		host_speed = (chan->speed != USB_SPEED_HIGH &&
+			      !chan->do_split) ? chan->speed : USB_SPEED_HIGH;
+
+		/* See how many bytes are in the periodic FIFO right now */
+		fifo_space = (dwc2_readl(hsotg->regs + HPTXSTS) &
+			      TXSTS_FSPCAVAIL_MASK) >> TXSTS_FSPCAVAIL_SHIFT;
+		bytes_in_fifo = sizeof(u32) *
+				(hsotg->core_params->host_perio_tx_fifo_size -
+				 fifo_space);
+
+		/*
+		 * Roughly estimate bus time for everything in the periodic
+		 * queue + our new transfer.  This is "rough" because we're
+		 * using a function that makes takes into account IN/OUT
+		 * and INT/ISO and we're just slamming in one value for all
+		 * transfers.  This should be an over-estimate and that should
+		 * be OK, but we can probably tighten it.
+		 */
+		xfer_ns = usb_calc_bus_time(host_speed, false, false,
+					    chan->xfer_len + bytes_in_fifo);
+		xfer_us = NS_TO_US(xfer_ns);
+
+		/* See what frame number we'll be at by the time we finish */
+		frame_number = dwc2_hcd_get_future_frame_number(hsotg, xfer_us);
+
+		/* This is when we were scheduled to be on the wire */
+		wire_frame = dwc2_frame_num_inc(chan->qh->next_active_frame, 1);
+
+		/*
+		 * If we'd finish _after_ the frame we're scheduled in then
+		 * it's hopeless.  Just schedule right away and hope for the
+		 * best.  Note that it _might_ be wise to call back into the
+		 * scheduler to pick a better frame, but this is better than
+		 * nothing.
+		 */
+		if (dwc2_frame_num_gt(frame_number, wire_frame)) {
+			dwc2_sch_vdbg(hsotg,
+				      "QH=%p EO MISS fr=%04x=>%04x (%+d)\n",
+				      chan->qh, wire_frame, frame_number,
+				      dwc2_frame_num_dec(frame_number,
+							 wire_frame));
+			wire_frame = frame_number;
+
+			/*
+			 * We picked a different frame number; communicate this
+			 * back to the scheduler so it doesn't try to schedule
+			 * another in the same frame.
+			 *
+			 * Remember that next_active_frame is 1 before the wire
+			 * frame.
+			 */
+			chan->qh->next_active_frame =
+				dwc2_frame_num_dec(frame_number, 1);
+		}
+
+		if (wire_frame & 1)
 			*hcchar |= HCCHAR_ODDFRM;
+		else
+			*hcchar &= ~HCCHAR_ODDFRM;
 	}
 }
 
diff --git a/drivers/usb/dwc2/hcd_queue.c b/drivers/usb/dwc2/hcd_queue.c
index 3abb34a5fc5b..5f909747b5a4 100644
--- a/drivers/usb/dwc2/hcd_queue.c
+++ b/drivers/usb/dwc2/hcd_queue.c
@@ -985,6 +985,14 @@ static int dwc2_next_periodic_start(struct dwc2_hsotg *hsotg,
 	 *   and next_active_frame are always 1 frame before we want things
 	 *   to be active and we assume we can still get scheduled in the
 	 *   current frame number.
+	 * - It's possible for start_active_frame (now incremented) to be
+	 *   next_active_frame if we got an EO MISS (even_odd miss) which
+	 *   basically means that we detected there wasn't enough time for
+	 *   the last packet and dwc2_hc_set_even_odd_frame() rescheduled us
+	 *   at the last second.  We want to make sure we don't schedule
+	 *   another transfer for the same frame.  My test webcam doesn't seem
+	 *   terribly upset by missing a transfer but really doesn't like when
+	 *   we do two transfers in the same frame.
 	 * - Some misses are expected.  Specifically, in order to work
 	 *   perfectly dwc2 really needs quite spectacular interrupt latency
 	 *   requirements.  It needs to be able to handle its interrupts
@@ -995,7 +1003,8 @@ static int dwc2_next_periodic_start(struct dwc2_hsotg *hsotg,
 	 *   guarantee that a system will have interrupt latency < 125 us, so
 	 *   we have to be robust to some misses.
 	 */
-	if (dwc2_frame_num_gt(prev_frame_number, qh->start_active_frame)) {
+	if (qh->start_active_frame == qh->next_active_frame ||
+	    dwc2_frame_num_gt(prev_frame_number, qh->start_active_frame)) {
 		u16 ideal_start = qh->start_active_frame;
 
 		/* Adjust interval as per gcd with plan length. */
-- 
2.7.0.rc3.207.g0ac5344

  parent reply	other threads:[~2016-01-29  2:21 UTC|newest]

Thread overview: 71+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-01-29  2:19 [PATCH v6 0/22] usb: dwc2: host: Fix and speed up all the stuff, especially with splits Douglas Anderson
2016-01-29  2:19 ` [PATCH v6 01/22] usb: dwc2: rockchip: Make the max_transfer_size automatic Douglas Anderson
2016-01-29  2:19 ` [PATCH v6 02/22] usb: dwc2: host: Get aligned DMA in a more supported way Douglas Anderson
2016-01-29  2:19 ` [PATCH v6 03/22] usb: dwc2: host: Set host_rx_fifo_size to 525 for rk3066 Douglas Anderson
2016-01-29  2:19 ` [PATCH v6 04/22] usb: dwc2: host: Avoid use of chan->qh after qh freed Douglas Anderson
     [not found] ` <1454034013-24657-1-git-send-email-dianders-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
2016-01-29  2:19   ` [PATCH v6 01/22] usb: dwc2: rockchip: Make the max_transfer_size automatic Douglas Anderson
2016-01-29  2:19   ` [PATCH v6 02/22] usb: dwc2: host: Get aligned DMA in a more supported way Douglas Anderson
2016-01-29  2:19   ` [PATCH v6 03/22] usb: dwc2: host: Set host_rx_fifo_size to 525 for rk3066 Douglas Anderson
2016-01-29  2:19   ` [PATCH v6 04/22] usb: dwc2: host: Avoid use of chan->qh after qh freed Douglas Anderson
2016-01-29  2:19   ` [PATCH v6 05/22] usb: dwc2: host: Always add to the tail of queues Douglas Anderson
2016-01-29  2:19   ` [PATCH v6 06/22] usb: dwc2: host: fix split transfer schedule sequence Douglas Anderson
2016-01-29  2:19   ` [PATCH v6 07/22] usb: dwc2: host: Add scheduler tracing Douglas Anderson
2016-01-29  2:19   ` [PATCH v6 08/22] usb: dwc2: host: Add a delay before releasing periodic bandwidth Douglas Anderson
2016-01-29  2:20   ` [PATCH v6 11/22] usb: dwc2: host: There's not really a TT for the root hub Douglas Anderson
2016-01-31  9:25     ` Kever Yang
2016-01-29  2:20   ` [PATCH v6 12/22] usb: dwc2: host: Use periodic interrupt even with DMA Douglas Anderson
2016-01-29  2:20   ` [PATCH v6 14/22] usb: dwc2: host: Reorder things in hcd_queue.c Douglas Anderson
2016-01-29  2:20   ` [PATCH v6 15/22] usb: dwc2: host: Split code out to make dwc2_do_reserve() Douglas Anderson
2016-01-29  2:20   ` [PATCH v6 17/22] usb: dwc2: host: Manage frame nums better in scheduler Douglas Anderson
     [not found]     ` <1454034013-24657-18-git-send-email-dianders-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
2016-02-03 20:29       ` Doug Anderson
2016-02-09  9:53         ` Herrero, Gregory
2016-02-03 20:29     ` Doug Anderson
2016-01-29  2:20   ` [PATCH v6 19/22] usb: dwc2: host: Add dwc2_hcd_get_future_frame_number() call Douglas Anderson
2016-01-29  2:20   ` [PATCH v6 21/22] usb: dwc2: host: Totally redo the microframe scheduler Douglas Anderson
2016-01-29  2:20   ` [PATCH v6 22/22] usb: dwc2: host: If using uframe scheduler, end splits better Douglas Anderson
2016-01-29  2:19 ` [PATCH v6 05/22] usb: dwc2: host: Always add to the tail of queues Douglas Anderson
2016-01-29  2:19 ` [PATCH v6 06/22] usb: dwc2: host: fix split transfer schedule sequence Douglas Anderson
2016-01-29  2:19 ` [PATCH v6 07/22] usb: dwc2: host: Add scheduler tracing Douglas Anderson
2016-01-29  2:19 ` [PATCH v6 08/22] usb: dwc2: host: Add a delay before releasing periodic bandwidth Douglas Anderson
2016-01-29  2:20 ` [PATCH v6 09/22] usb: dwc2: host: Giveback URB in tasklet context Douglas Anderson
2016-01-29  2:20 ` [PATCH v6 10/22] usb: dwc2: host: Properly set the HFIR Douglas Anderson
     [not found]   ` <1454034013-24657-11-git-send-email-dianders-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
2016-01-31  9:23     ` Kever Yang
2016-01-31 22:19       ` Doug Anderson
2016-02-10  2:08         ` John Youn
2016-01-31  9:23   ` Kever Yang
2016-01-29  2:20 ` [PATCH v6 11/22] usb: dwc2: host: There's not really a TT for the root hub Douglas Anderson
2016-01-29  2:20 ` [PATCH v6 12/22] usb: dwc2: host: Use periodic interrupt even with DMA Douglas Anderson
2016-01-29  2:20 ` [PATCH v6 13/22] usb: dwc2: host: Rename some fields in struct dwc2_qh Douglas Anderson
2016-01-29  2:20 ` [PATCH v6 14/22] usb: dwc2: host: Reorder things in hcd_queue.c Douglas Anderson
2016-01-29  2:20 ` [PATCH v6 15/22] usb: dwc2: host: Split code out to make dwc2_do_reserve() Douglas Anderson
2016-01-29  2:20 ` [PATCH v6 16/22] usb: dwc2: host: Add scheduler logging for missed SOFs Douglas Anderson
2016-01-29  2:20 ` [PATCH v6 17/22] usb: dwc2: host: Manage frame nums better in scheduler Douglas Anderson
2016-01-29  2:20 ` [PATCH v6 18/22] usb: dwc2: host: Schedule periodic right away if it's time Douglas Anderson
2016-01-31  9:36   ` Kever Yang
     [not found]   ` <1454034013-24657-19-git-send-email-dianders-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
2016-01-31  9:36     ` Kever Yang
2016-01-31 22:09       ` Doug Anderson
     [not found]       ` <56ADD580.1070505-TNX95d0MmH7DzftRWevZcw@public.gmane.org>
2016-01-31 22:09         ` Doug Anderson
2016-02-01  3:32           ` Kever Yang
     [not found]             ` <56AED1B6.7020409-TNX95d0MmH7DzftRWevZcw@public.gmane.org>
2016-02-01  4:36               ` Doug Anderson
     [not found]                 ` <CAD=FV=XJgmXm255=cmtqpVM0iJeWCzC5O8BtE2XY4y5Txvk+gg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-02-02  0:36                   ` Doug Anderson
     [not found]                     ` <CAD=FV=UXoRB74yCePrNqC7gUJM=rnz484peAR=n3zOpCiJ2UFw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-02-02  7:04                       ` Kever Yang
     [not found]                         ` <56B054FD.5090000-TNX95d0MmH7DzftRWevZcw@public.gmane.org>
2016-02-02 23:28                           ` Doug Anderson
2016-02-02 23:28                         ` Doug Anderson
2016-02-02  7:04                     ` Kever Yang
2016-02-02  0:36                 ` Doug Anderson
2016-02-01  4:36             ` Doug Anderson
2016-01-29  2:20 ` [PATCH v6 19/22] usb: dwc2: host: Add dwc2_hcd_get_future_frame_number() call Douglas Anderson
2016-01-29  2:20 ` Douglas Anderson [this message]
2016-02-02  7:46   ` [PATCH v6 20/22] usb: dwc2: host: Properly set even/odd frame Kever Yang
     [not found]     ` <56B05EBF.9090804-TNX95d0MmH7DzftRWevZcw@public.gmane.org>
2016-02-02 22:47       ` Doug Anderson
     [not found]         ` <CAD=FV=Udm3teg+K62B9TE+b+5HNHSSU0CaVSA57Lau+xZqwdcw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-02-03  7:47           ` Kever Yang
2016-02-03  7:47         ` Kever Yang
2016-02-02 22:47     ` Doug Anderson
2016-01-29  2:20 ` [PATCH v6 21/22] usb: dwc2: host: Totally redo the microframe scheduler Douglas Anderson
2016-01-29  2:20 ` [PATCH v6 22/22] usb: dwc2: host: If using uframe scheduler, end splits better Douglas Anderson
2016-02-02 23:57 ` [PATCH v6 0/22] usb: dwc2: host: Fix and speed up all the stuff, especially with splits John Youn
2016-02-03 18:23   ` Doug Anderson
2016-02-10  2:25     ` John Youn

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