Commit 17b63704 authored Aug 29, 2019 by Thinh Nguyen Committed by Felipe Balbi Aug 30, 2019

usb: dwc3: gadget: Workaround Mirosoft's BESL check



While testing our host system using Microsoft's usb stack against our
gadget for various BESL values, we found an issue with their usb stack
when the recommended baseline BESL value is 0 (125us) or when the deep
BESL is 1 or less. The Windows host will issue a usb reset immediately
after it receives the extended BOS descriptor and the enumeration will
fail after a few attempts.

To keep compatibility with Microsoft's host usb stack, let's workaround
this issue by using the recommended baseline BESL of 1 (or 150us)
and clamp the deep BESL value within 2 to 15.

This was tested against Windows 10 build 18956.

Signed-off-by: Thinh Nguyen <thinhn@synopsys.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

parent 6bbf87a1

drivers/usb/dwc3/gadget.c

+12 −2

Original line number	Diff line number	Diff line
		@@ -2083,9 +2083,19 @@ static void dwc3_gadget_config_params(struct usb_gadget *g,

		/* Recommended BESL */
		if (!dwc->dis_enblslpm_quirk) {
		params->besl_baseline = 0;
		/*
		* If the recommended BESL baseline is 0 or if the BESL deep is
		* less than 2, Microsoft's Windows 10 host usb stack will issue
		* a usb reset immediately after it receives the extended BOS
		* descriptor and the enumeration will fail. To maintain
		* compatibility with the Windows' usb stack, let's set the
		* recommended BESL baseline to 1 and clamp the BESL deep to be
		* within 2 to 15.
		*/
		params->besl_baseline = 1;
		if (dwc->is_utmi_l1_suspend)
		params->besl_deep = min_t(u8, dwc->hird_threshold, 15);
		params->besl_deep =
		clamp_t(u8, dwc->hird_threshold, 2, 15);
		}

		/* U1 Device exit Latency */

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