Skip to contentSkip to conversation

usb: dwc3: gadget: check if dep->frame_number is still valid

PATCH New Felipe Balbi 1 participant 1 message Nov 9, 2018 USB

lore
Share & tools
lore

Felipe Balbi

author
#0 lore raw

PATCH 4/4 usb: dwc3: gadget: check if dep->frame_number is still valid

Hi again,

Quoted 34 lines · Felipe Balbi

In the case of interval of 1ms, it will start on the next interval.

Quoted 6 lines

frame_number + max(4, interval) will start at least 4 uframes in the future.

In any case, what about immediately retry the START_TRANSFER command with a new frame_number + (interval*retry) should it fail with bus-expiry? You can set the number of retries to maybe 5 times. This should remove the need to do time stamping.

That seems like a good idea. Something like below? (on top of $subject)

modified drivers/usb/dwc3/core.h

(quoted diff) +1 -0
@@ -37,6 +37,7 @@
 #define DWC3_EP0_SETUP_SIZE	512
 #define DWC3_ENDPOINTS_NUM	32
 #define DWC3_XHCI_RESOURCES_NUM	2
+#define DWC3_ISOC_MAX_RETRIES	5
 
 #define DWC3_SCRATCHBUF_SIZE	4096	/* each buffer is assumed to be 4KiB */
 #define DWC3_EVENT_BUFFERS_SIZE	4096

modified drivers/usb/dwc3/gadget.c

(quoted diff) +3 -1
@@ -1271,20 +1271,29 @@ static int __dwc3_gadget_start_isoc(struct dwc3_ep *dep)
 	u64 current_timestamp;
 	u64 diff_timestamp;
 	u32 elapsed_frames;
+	int retries;
+	int delta = 1
+	int ret;
 
 	if (list_empty(&dep->pending_list)) {
 		dep->flags |= DWC3_EP_PENDING_REQUEST;
 		return -EAGAIN;
 	}
 
-	current_timestamp = ktime_get_ns();

Review static int __dwc3_gadget_start_isoc(struct dwc3_ep *dep) · line 1288

Quoted 10 lines
(quoted diff) +5 -4
-	diff_timestamp = current_timestamp - dep->frame_timestamp;
-	elapsed_frames = DIV_ROUND_UP_ULL(diff_timestamp, 125000);
+	for (i = 0; i < DWC3_ISOC_MAX_RETRIES; i++) {
+		current_timestamp = ktime_get_ns();
+		diff_timestamp = current_timestamp - dep->frame_timestamp;
+		elapsed_frames = DIV_ROUND_UP_ULL(diff_timestamp, 125000);
 
-	dep->frame_number += elapsed_frames;
-	dep->frame_number = DWC3_ALIGN_FRAME(dep);
+		dep->frame_number += elapsed_frames + (delta * i);

the other possibility is that we can call DWC3_ALIGN_FRAME() n times since that will put the transfer on the following interval. That would look like so:

modified drivers/usb/dwc3/core.h
@@ -37,6 +37,7 @@
#define DWC3_EP0_SETUP_SIZE 512
#define DWC3_ENDPOINTS_NUM 32
#define DWC3_XHCI_RESOURCES_NUM 2
+#define DWC3_ISOC_MAX_RETRIES 5

#define DWC3_SCRATCHBUF_SIZE 4096 /* each buffer is assumed to be 4KiB */
#define DWC3_EVENT_BUFFERS_SIZE 4096
modified drivers/usb/dwc3/gadget.c
@@ -27,7 +27,7 @@
#include "gadget.h"
#include "io.h"

-#define DWC3_ALIGN_FRAME(d) (((d)->frame_number + (d)->interval) \
+#define DWC3_ALIGN_FRAME(d, n) (((d)->frame_number + ((d)->interval * (n))) \
& ~((d)->interval - 1))

/**
@@ -1271,20 +1271,28 @@ static int __dwc3_gadget_start_isoc(struct dwc3_ep *dep)
u64 current_timestamp;
u64 diff_timestamp;
u32 elapsed_frames;
+ int retries;
+ int ret;

if (list_empty(&dep->pending_list)) {
dep->flags |= DWC3_EP_PENDING_REQUEST; return -EAGAIN;
}

- current_timestamp = ktime_get_ns();
- diff_timestamp = current_timestamp - dep->frame_timestamp;
- elapsed_frames = DIV_ROUND_UP_ULL(diff_timestamp, 125000);
+ for (i = 0; i < DWC3_ISOC_MAX_RETRIES; i++) {
+ current_timestamp = ktime_get_ns();
+ diff_timestamp = current_timestamp - dep->frame_timestamp;
+ elapsed_frames = DIV_ROUND_UP_ULL(diff_timestamp, 125000);

- dep->frame_number += elapsed_frames;
- dep->frame_number = DWC3_ALIGN_FRAME(dep);
+ dep->frame_number += elapsed_frames;
+ dep->frame_number = DWC3_ALIGN_FRAME(dep, i);

- return __dwc3_gadget_kick_transfer(dep);
+ ret = __dwc3_gadget_kick_transfer(dep);
+ if (ret != -EAGAIN)
+ break;
+ }
+
+ return ret;
}

static int __dwc3_gadget_ep_queue(struct dwc3_ep *dep, struct dwc3_request *req)