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authorMichael Olbrich <m.olbrich@pengutronix.de>2020-07-01 20:24:52 +0200
committerFelipe Balbi <balbi@kernel.org>2020-07-24 16:45:15 +0300
commitc5a7092f401535d8a9159be963b0c318393c2a78 (patch)
tree66c907e9f679ff3feca66231ccbe4c9992586e3e /drivers/usb
parentca14378560db5440893404a639d69846f46eb70e (diff)
usb: dwc3: gadget: make starting isoc transfers more robust
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 Otherwise the frame number is outdated and start transfer will fail, even with several retries. 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. Reviewed-by: Thinh Nguyen <thinhn@synopsys.com> Signed-off-by: Michael Olbrich <m.olbrich@pengutronix.de> Signed-off-by: Michael Tretter <m.tretter@pengutronix.de> Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de> Signed-off-by: Felipe Balbi <balbi@kernel.org>
Diffstat (limited to 'drivers/usb')
-rw-r--r--drivers/usb/dwc3/gadget.c22
1 files changed, 22 insertions, 0 deletions
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index ca27907667a3..779b17373929 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1463,6 +1463,7 @@ static int dwc3_gadget_start_isoc_quirk(struct dwc3_ep *dep)
static int __dwc3_gadget_start_isoc(struct dwc3_ep *dep)
{
+ const struct usb_endpoint_descriptor *desc = dep->endpoint.desc;
struct dwc3 *dwc = dep->dwc;
int ret;
int i;
@@ -1480,6 +1481,27 @@ static int __dwc3_gadget_start_isoc(struct dwc3_ep *dep)
return dwc3_gadget_start_isoc_quirk(dep);
}
+ if (desc->bInterval <= 14 &&
+ dwc->gadget.speed >= USB_SPEED_HIGH) {
+ u32 frame = __dwc3_gadget_get_frame(dwc);
+ bool rollover = frame <
+ (dep->frame_number & DWC3_FRNUMBER_MASK);
+
+ /*
+ * 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+ * out of date.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.
+ */
+
+ dep->frame_number = (dep->frame_number & ~DWC3_FRNUMBER_MASK) |
+ 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);