usb: dwc2: host: Totally redo the microframe scheduler

This totally reimplements the microframe scheduler in dwc2 to attempt to
handle periodic splits properly.  The old code didn't even try, so this
was a significant effort since periodic splits are one of the most
complicated things in USB.

I've attempted to keep the old "don't use the microframe" schduler
around for now, but not sure it's needed.  It has also only been lightly
tested.

I think it's pretty certain that this scheduler isn't perfect and might
have some bugs, but it seems much better than what was there before.
With this change my stressful USB test (USB webcam + USB audio + some
keyboards) crackles less.

Acked-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>

1 files changed, 84 insertions, 3 deletions

diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
index 8edd0b4..2b5a706 100644
--- a/drivers/usb/dwc2/hcd.c
+++ b/drivers/usb/dwc2/hcd.c
@@ -2252,6 +2252,90 @@ void dwc2_host_hub_info(struct dwc2_hsotg *hsotg, void *context, int *hub_addr,
 	*hub_port = urb->dev->ttport;
 }
 
+/**
+ * dwc2_host_get_tt_info() - Get the dwc2_tt associated with context
+ *
+ * This will get the dwc2_tt structure (and ttport) associated with the given
+ * context (which is really just a struct urb pointer).
+ *
+ * The first time this is called for a given TT we allocate memory for our
+ * structure.  When everyone is done and has called dwc2_host_put_tt_info()
+ * then the refcount for the structure will go to 0 and we'll free it.
+ *
+ * @hsotg:     The HCD state structure for the DWC OTG controller.
+ * @qh:        The QH structure.
+ * @context:   The priv pointer from a struct dwc2_hcd_urb.
+ * @mem_flags: Flags for allocating memory.
+ * @ttport:    We'll return this device's port number here.  That's used to
+ *             reference into the bitmap if we're on a multi_tt hub.
+ *
+ * Return: a pointer to a struct dwc2_tt.  Don't forget to call
+ *         dwc2_host_put_tt_info()!  Returns NULL upon memory alloc failure.
+ */
+
+struct dwc2_tt *dwc2_host_get_tt_info(struct dwc2_hsotg *hsotg, void *context,
+				      gfp_t mem_flags, int *ttport)
+{
+	struct urb *urb = context;
+	struct dwc2_tt *dwc_tt = NULL;
+
+	if (urb->dev->tt) {
+		*ttport = urb->dev->ttport;
+
+		dwc_tt = urb->dev->tt->hcpriv;
+		if (dwc_tt == NULL) {
+			size_t bitmap_size;
+
+			/*
+			 * For single_tt we need one schedule.  For multi_tt
+			 * we need one per port.
+			 */
+			bitmap_size = DWC2_ELEMENTS_PER_LS_BITMAP *
+				      sizeof(dwc_tt->periodic_bitmaps[0]);
+			if (urb->dev->tt->multi)
+				bitmap_size *= urb->dev->tt->hub->maxchild;
+
+			dwc_tt = kzalloc(sizeof(*dwc_tt) + bitmap_size,
+					 mem_flags);
+			if (dwc_tt == NULL)
+				return NULL;
+
+			dwc_tt->usb_tt = urb->dev->tt;
+			dwc_tt->usb_tt->hcpriv = dwc_tt;
+		}
+
+		dwc_tt->refcount++;
+	}
+
+	return dwc_tt;
+}
+
+/**
+ * dwc2_host_put_tt_info() - Put the dwc2_tt from dwc2_host_get_tt_info()
+ *
+ * Frees resources allocated by dwc2_host_get_tt_info() if all current holders
+ * of the structure are done.
+ *
+ * It's OK to call this with NULL.
+ *
+ * @hsotg:     The HCD state structure for the DWC OTG controller.
+ * @dwc_tt:    The pointer returned by dwc2_host_get_tt_info.
+ */
+void dwc2_host_put_tt_info(struct dwc2_hsotg *hsotg, struct dwc2_tt *dwc_tt)
+{
+	/* Model kfree and make put of NULL a no-op */
+	if (dwc_tt == NULL)
+		return;
+
+	WARN_ON(dwc_tt->refcount < 1);
+
+	dwc_tt->refcount--;
+	if (!dwc_tt->refcount) {
+		dwc_tt->usb_tt->hcpriv = NULL;
+		kfree(dwc_tt);
+	}
+}
+
 int dwc2_host_get_speed(struct dwc2_hsotg *hsotg, void *context)
 {
 	struct urb *urb = context;
@@ -3197,9 +3281,6 @@ int dwc2_hcd_init(struct dwc2_hsotg *hsotg, int irq)
 		hsotg->hc_ptr_array[i] = channel;
 	}
 
-	if (hsotg->core_params->uframe_sched > 0)
-		dwc2_hcd_init_usecs(hsotg);
-
 	/* Initialize hsotg start work */
 	INIT_DELAYED_WORK(&hsotg->start_work, dwc2_hcd_start_func);