On Thu, Jun 25, 2020 at 08:20:26PM +0000, Thinh Nguyen wrote:
Thinh Nguyen wrote:Thinh Nguyen wrote:Hi, Michael Grzeschik wrote:Hi! On Wed, Jun 24, 2020 at 07:26:42PM +0000, Thinh Nguyen wrote:Michael Grzeschik wrote:From: Michael Olbrich <m.olbrich@xxxxxxxxxxxxxx> Currently __dwc3_gadget_start_isoc must be called very shortly after XferNotReady. Otherwise the frame number is outdated and start transfer will fail, even with several retries.Did you try with the recent update for isoc? (e.i., after 5 START_TRANSFER failures, the driver will issue END_TRANSFER to retry on the next XferNotReady event) Let me know if you still run into issues with that.Yes. Without my patch I still see the issue. Event with the retry machanism. It is even worse. I even missed one additional patch, I had on top this one. See my note below.Ok. Can you clarify what issue you're seeing?
Yes. There are many missed xfer events, flooding the uvc gadget function driver.
DSTS provides the lower 14 bit of the frame number. Use it in combination with the frame number provided by XferNotReady to guess the current frame number. This will succeed unless more than one 14 rollover has happened since XferNotReady. Start transfer might still fail if the frame number is increased immediately after DSTS is read. So retries are still needed. Don't drop the current request if this happens. This way it is not lost and can be used immediately to try again with the next frame number. With this change, __dwc3_gadget_start_isoc is still not successfully in all cases bit it increases the acceptable delay after XferNotReady significantly. Signed-off-by: Michael Olbrich <m.olbrich@xxxxxxxxxxxxxx> Signed-off-by: Michael Tretter <m.tretter@xxxxxxxxxxxxxx> Signed-off-by: Michael Grzeschik <m.grzeschik@xxxxxxxxxxxxxx> --- v1 -> v2: - removed last_frame_number from struct - included rollover variable drivers/usb/dwc3/gadget.c | 37 +++++++++++++++++++++++++------------ 1 file changed, 25 insertions(+), 12 deletions(-) diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c index 421a0f73110a40b..0962ddd7fbf6ae6 100644 --- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -1276,7 +1276,7 @@ static void dwc3_prepare_trbs(struct dwc3_ep *dep) static void dwc3_gadget_ep_cleanup_cancelled_requests(struct dwc3_ep *dep); -static int __dwc3_gadget_kick_transfer(struct dwc3_ep *dep) +static int __dwc3_gadget_kick_transfer(struct dwc3_ep *dep, bool keep_req)Any reason to have keep_req? With the recent changes, if dwc3_send_gadget_ep_cmd() returns -EAGAIN, then the controller driver won't give back the request.Yes, we don't need the keep_req. I tried this and it worked without. I will remove the parameter in v3.{ struct dwc3_gadget_ep_cmd_params params; struct dwc3_request *req; @@ -1314,12 +1314,9 @@ static int __dwc3_gadget_kick_transfer(struct dwc3_ep *dep) } ret = dwc3_send_gadget_ep_cmd(dep, cmd, ¶ms); - if (ret < 0) { + if (ret < 0 && (!keep_req || ret != -EAGAIN)) { struct dwc3_request *tmp; - if (ret == -EAGAIN) - return ret; - dwc3_stop_active_transfer(dep, true, true); list_for_each_entry_safe(req, tmp, &dep->started_list, list) @@ -1335,7 +1332,7 @@ static int __dwc3_gadget_kick_transfer(struct dwc3_ep *dep) if (dep->stream_capable && req->request.is_last) dep->flags |= DWC3_EP_WAIT_TRANSFER_COMPLETE; - return 0; + return ret; } static int __dwc3_gadget_get_frame(struct dwc3 *dwc) @@ -1458,7 +1455,7 @@ static int dwc3_gadget_start_isoc_quirk(struct dwc3_ep *dep) dep->start_cmd_status = 0; dep->combo_num = 0; - return __dwc3_gadget_kick_transfer(dep); + return __dwc3_gadget_kick_transfer(dep, false); } static int __dwc3_gadget_start_isoc(struct dwc3_ep *dep) @@ -1481,9 +1478,25 @@ static int __dwc3_gadget_start_isoc(struct dwc3_ep *dep) } for (i = 0; i < DWC3_ISOC_MAX_RETRIES; i++) { - dep->frame_number = DWC3_ALIGN_FRAME(dep, i + 1); + /* + * frame_number is set from XferNotReady and may be already + * out of date. DSTS only provides the lower 14 bit of the + * current frame number. So add the upper two bits of + * frame_number and handle a possible rollover. + * This will provide the correct frame_number unless more than + * rollover has happened since XferNotReady. + */ + u32 frame = __dwc3_gadget_get_frame(dwc); + bool rollover = frame < (dep->frame_number & 0x3fff); + + dep->frame_number = (dep->frame_number & ~0x3fff) | frame; + if (rollover) + dep->frame_number += BIT(14); + + dep->frame_number = DWC3_ALIGN_FRAME(dep, 1);This is not enough, we have to add i into the alignment to ensure that the stream is not failing: dep->frame_number = DWC3_ALIGN_FRAME(dep, i + 2); I am even thiking to move the frame number calculation into the DWC3_DEPCMD_STARTTRANSFER code path of dwc3_send_gadget_ep_cmd. But this will break the dwc3_gadget_start_isoc_quirk function. What do you think?You shouldn't be keep calling __dwc3_gadget_get_frame() in a loop. You should do all these calculation to get the current frame_number only once before entering the retry loop. The issue here is we don't know when the XferNotReady event will be handled, which may be too late and multiple uframe had gone by. But once the event is being handled, it shouldn't take much time at all. That means __dwc3_gadget_get_frame() will return the same value. So, we need something like this: diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c index f66ff7fd87a9..1cd73c2dbe71 100644 --- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -1709,6 +1709,8 @@ static int dwc3_gadget_start_isoc_quirk(struct dwc3_ep *dep) static int __dwc3_gadget_start_isoc(struct dwc3_ep *dep) { struct dwc3 *dwc = dep->dwc; + u32 current_frame; + bool rollover; int ret; int i; @@ -1725,6 +1727,13 @@ static int __dwc3_gadget_start_isoc(struct dwc3_ep *dep) return dwc3_gadget_start_isoc_quirk(dep); } + current_frame = __dwc3_gadget_get_frame(dwc); + rollover = current_frame < (dep->frame_number & 0x3fff); + + dep->frame_number = (dep->frame_number & ~0x3fff) | current_frame; + if (rollover) + dep->frame_number += BIT(14); + for (i = 0; i < DWC3_ISOC_MAX_RETRIES; i++) { dep->frame_number = DWC3_ALIGN_FRAME(dep, i + 1); (Please create a macro for 0x3fff mask)Forgot a couple of notes: 1) If bInterval is greater than 14, don't attempt to get current frame from DSTS and ignore this mechanism. 2) The rollover check needs to account for number of uframes per interval. If the difference is less than an interval length, then no need to update dep->frame_number.Ignore number 2), DWC3_ALIGN_FRAME() should take care of that...
All right, I added the following changes to v3 before running
the retry loop.
if (desc->bInterval <= 14) {
u32 current_frame = __dwc3_gadget_get_frame(dwc);
bool rollover = current_frame < (dep->frame_number & 0x3fff);
dep->frame_number = (dep->frame_number & ~0x3fff) | current_frame;
if (rollover)
dep->frame_number += BIT(14);
dep->frame_number += BIT(14);
}
Regards,
Michael
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