Hi again,
Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx> writes:
> In the case of interval of 1ms, it will start on the next interval.
>> 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
> @@ -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
> @@ -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();
> - 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)
--
balbi
Attachment:
signature.asc
Description: PGP signature
