[PATCH v2 3/4] usb: dwc2: host: Add a delay before releasing periodic bandwidth
We'd like to be able to use HCD_BH in order to speed up the dwc2 host
interrupt handler quite a bit. However, according to the kernel doc for
usb_submit_urb() (specifically the part about "Reserved Bandwidth
Transfers"), we need to keep a reservation active as long as a device
driver keeps submitting. That was easy to do when we gave back the URB
in the interrupt context: we just looked at when our queue was empty and
released the reserved bandwidth then. ...but now we need a little more
complexity.
We'll follow EHCI's lead in commit 9118f9eb4f1e ("USB: EHCI: improve
interrupt qh unlink") and add a 5ms delay. Since we don't have a whole
timer infrastructure in dwc2, we'll just add a timer per QH. The
overhead for this is very small.
Signed-off-by: Douglas Anderson
---
Changes in v2:
- Periodic bandwidth release delay new for V2
drivers/usb/dwc2/hcd.h | 6 ++
drivers/usb/dwc2/hcd_queue.c | 232 +--
2 files changed, 184 insertions(+), 54 deletions(-)
diff --git a/drivers/usb/dwc2/hcd.h b/drivers/usb/dwc2/hcd.h
index 8a4486e1a542..b75a8b116f6e 100644
--- a/drivers/usb/dwc2/hcd.h
+++ b/drivers/usb/dwc2/hcd.h
@@ -211,6 +211,7 @@ enum dwc2_transaction_type {
/**
* struct dwc2_qh - Software queue head structure
*
+ * @hsotg: The HCD state structure for the DWC OTG controller
* @ep_type:Endpoint type. One of the following values:
* - USB_ENDPOINT_XFER_CONTROL
* - USB_ENDPOINT_XFER_BULK
@@ -247,13 +248,16 @@ enum dwc2_transaction_type {
* @n_bytes:Xfer Bytes array. Each element corresponds to a
transfer
* descriptor and indicates original XferSize value for
the
* descriptor
+ * @unreserve_timer:Timer for releasing periodic reservation.
* @tt_buffer_dirty True if clear_tt_buffer_complete is pending
+ * @unreserve_pending: True if we planned to unreserve but haven't yet.
*
* A Queue Head (QH) holds the static characteristics of an endpoint and
* maintains a list of transfers (QTDs) for that endpoint. A QH structure may
* be entered in either the non-periodic or periodic schedule.
*/
struct dwc2_qh {
+ struct dwc2_hsotg *hsotg;
u8 ep_type;
u8 ep_is_in;
u16 maxp;
@@ -275,7 +279,9 @@ struct dwc2_qh {
struct dwc2_hcd_dma_desc *desc_list;
dma_addr_t desc_list_dma;
u32 *n_bytes;
+ struct timer_list unreserve_timer;
unsigned tt_buffer_dirty:1;
+ unsigned unreserve_pending:1;
};
/**
diff --git a/drivers/usb/dwc2/hcd_queue.c b/drivers/usb/dwc2/hcd_queue.c
index 3e1edafc593c..10f27b594e92 100644
--- a/drivers/usb/dwc2/hcd_queue.c
+++ b/drivers/usb/dwc2/hcd_queue.c
@@ -53,6 +53,94 @@
#include "core.h"
#include "hcd.h"
+/* Wait this long before releasing periodic reservation */
+#define DWC2_UNRESERVE_DELAY (msecs_to_jiffies(5))
+
+/**
+ * dwc2_do_unreserve() - Actually release the periodic reservation
+ *
+ * This function actually releases the periodic bandwidth that was reserved
+ * by the given qh.
+ *
+ * @hsotg: The HCD state structure for the DWC OTG controller
+ * @qh:QH for the periodic transfer.
+ */
+static void dwc2_do_unreserve(struct dwc2_hsotg *hsotg, struct dwc2_qh *qh)
+{
+ assert_spin_locked(>lock);
+
+ WARN_ON(!qh->unreserve_pending);
+
+ if (WARN_ON(!list_empty(>qh_list_entry)))
+ list_del_init(>qh_list_entry);
+
+ /* Update claimed usecs per (micro)frame */
+ hsotg->periodic_usecs -= qh->usecs;
+
+ if (hsotg->core_params->uframe_sched > 0) {
+ int i;
+
+ for (i = 0; i < 8; i++) {
+ hsotg->frame_usecs[i] += qh->frame_usecs[i];
+ qh->frame_usecs[i] = 0;
+ }
+ } else {
+ /* Release periodic channel reservation */
+ hsotg->periodic_channels--;
+ }
+
+ /* No more unreserve pending--we're did it */
+ qh->unreserve_pending = false;
+}
+
+/**
+ * dwc2_unreserve_timer_fn() - Timer function to release periodic reservation
+ *
+ * According to the kernel doc for usb_submit_urb() (specifically the part
about
+ * "Reserved Bandwidth Transfers"), we need to keep a reservation active as
+ * long as a device driver keeps submitting. Since we're using HCD_BH to give
+ * back the URB we need to give the driver a little bit of time before we
+ * release the reservation. This worker is called after the appropriate
+ * delay.
+ *
+ * @work: Pointer to a qh unreserve_work.
+ */
+static void dwc2_unreserve_timer_fn(unsigned long data)
+{
+ struct dwc2_qh *qh = (struct dwc2_qh *)data;
+ struct dwc2_hsotg *hsotg = qh->hsotg;
+ unsigned long flags;
+
+ /*
+* Wait for the lock, or for us to be scheduled again. We
+* could be scheduled again if:
+* - We started executing but didn't get the lock
[PATCH v2 3/4] usb: dwc2: host: Add a delay before releasing periodic bandwidth
We'd like to be able to use HCD_BH in order to speed up the dwc2 host
interrupt handler quite a bit. However, according to the kernel doc for
usb_submit_urb() (specifically the part about "Reserved Bandwidth
Transfers"), we need to keep a reservation active as long as a device
driver keeps submitting. That was easy to do when we gave back the URB
in the interrupt context: we just looked at when our queue was empty and
released the reserved bandwidth then. ...but now we need a little more
complexity.
We'll follow EHCI's lead in commit 9118f9eb4f1e ("USB: EHCI: improve
interrupt qh unlink") and add a 5ms delay. Since we don't have a whole
timer infrastructure in dwc2, we'll just add a timer per QH. The
overhead for this is very small.
Signed-off-by: Douglas Anderson
---
Changes in v2:
- Periodic bandwidth release delay new for V2
drivers/usb/dwc2/hcd.h | 6 ++
drivers/usb/dwc2/hcd_queue.c | 232 +--
2 files changed, 184 insertions(+), 54 deletions(-)
diff --git a/drivers/usb/dwc2/hcd.h b/drivers/usb/dwc2/hcd.h
index 8a4486e1a542..b75a8b116f6e 100644
--- a/drivers/usb/dwc2/hcd.h
+++ b/drivers/usb/dwc2/hcd.h
@@ -211,6 +211,7 @@ enum dwc2_transaction_type {
/**
* struct dwc2_qh - Software queue head structure
*
+ * @hsotg: The HCD state structure for the DWC OTG controller
* @ep_type:Endpoint type. One of the following values:
* - USB_ENDPOINT_XFER_CONTROL
* - USB_ENDPOINT_XFER_BULK
@@ -247,13 +248,16 @@ enum dwc2_transaction_type {
* @n_bytes:Xfer Bytes array. Each element corresponds to a
transfer
* descriptor and indicates original XferSize value for
the
* descriptor
+ * @unreserve_timer:Timer for releasing periodic reservation.
* @tt_buffer_dirty True if clear_tt_buffer_complete is pending
+ * @unreserve_pending: True if we planned to unreserve but haven't yet.
*
* A Queue Head (QH) holds the static characteristics of an endpoint and
* maintains a list of transfers (QTDs) for that endpoint. A QH structure may
* be entered in either the non-periodic or periodic schedule.
*/
struct dwc2_qh {
+ struct dwc2_hsotg *hsotg;
u8 ep_type;
u8 ep_is_in;
u16 maxp;
@@ -275,7 +279,9 @@ struct dwc2_qh {
struct dwc2_hcd_dma_desc *desc_list;
dma_addr_t desc_list_dma;
u32 *n_bytes;
+ struct timer_list unreserve_timer;
unsigned tt_buffer_dirty:1;
+ unsigned unreserve_pending:1;
};
/**
diff --git a/drivers/usb/dwc2/hcd_queue.c b/drivers/usb/dwc2/hcd_queue.c
index 3e1edafc593c..10f27b594e92 100644
--- a/drivers/usb/dwc2/hcd_queue.c
+++ b/drivers/usb/dwc2/hcd_queue.c
@@ -53,6 +53,94 @@
#include "core.h"
#include "hcd.h"
+/* Wait this long before releasing periodic reservation */
+#define DWC2_UNRESERVE_DELAY (msecs_to_jiffies(5))
+
+/**
+ * dwc2_do_unreserve() - Actually release the periodic reservation
+ *
+ * This function actually releases the periodic bandwidth that was reserved
+ * by the given qh.
+ *
+ * @hsotg: The HCD state structure for the DWC OTG controller
+ * @qh:QH for the periodic transfer.
+ */
+static void dwc2_do_unreserve(struct dwc2_hsotg *hsotg, struct dwc2_qh *qh)
+{
+ assert_spin_locked(>lock);
+
+ WARN_ON(!qh->unreserve_pending);
+
+ if (WARN_ON(!list_empty(>qh_list_entry)))
+ list_del_init(>qh_list_entry);
+
+ /* Update claimed usecs per (micro)frame */
+ hsotg->periodic_usecs -= qh->usecs;
+
+ if (hsotg->core_params->uframe_sched > 0) {
+ int i;
+
+ for (i = 0; i < 8; i++) {
+ hsotg->frame_usecs[i] += qh->frame_usecs[i];
+ qh->frame_usecs[i] = 0;
+ }
+ } else {
+ /* Release periodic channel reservation */
+ hsotg->periodic_channels--;
+ }
+
+ /* No more unreserve pending--we're did it */
+ qh->unreserve_pending = false;
+}
+
+/**
+ * dwc2_unreserve_timer_fn() - Timer function to release periodic reservation
+ *
+ * According to the kernel doc for usb_submit_urb() (specifically the part
about
+ * "Reserved Bandwidth Transfers"), we need to keep a reservation active as
+ * long as a device driver keeps submitting. Since we're using HCD_BH to give
+ * back the URB we need to give the driver a little bit of time before we
+ * release the reservation. This worker is called after the appropriate
+ * delay.
+ *
+ * @work: Pointer to a qh unreserve_work.
+ */
+static void dwc2_unreserve_timer_fn(unsigned long data)
+{
+ struct dwc2_qh *qh = (struct dwc2_qh *)data;
+ struct dwc2_hsotg *hsotg = qh->hsotg;
+ unsigned long flags;
+
+ /*
+* Wait for the lock, or for us to be scheduled again. We
+* could be scheduled again if:
+* - We started executing
