dt-bindings: usb: dwc3: Add snps,host-vbus-glitches-quirk avoid vbus glitch
authorRan Wang <ran.wang_1@nxp.com>
Wed, 24 Jan 2024 15:25:24 +0000 (10:25 -0500)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Sun, 28 Jan 2024 01:39:09 +0000 (17:39 -0800)
commitbc83a87759cabbf6f3366568e44bda088b315204
tree113b0665fb2ac0975b47e3c9f0d04a6e49acbc59
parentc35ba0ac48355df1d11fcce85945f76c42d250ac
dt-bindings: usb: dwc3: Add snps,host-vbus-glitches-quirk avoid vbus glitch

When DWC3 is set to host mode by programming register DWC3_GCTL, VBUS
(or its control signal) will turn on immediately on related Root Hub
ports. Then the VBUS will be de-asserted for a little while during xhci
reset (conducted by xhci driver) for a little while and back to normal.

This VBUS glitch might cause some USB devices emuration fail if kernel
boot with them connected. One SW workaround which can fix this is to
program all PORTSC[PP] to 0 to turn off VBUS immediately after setting
host mode in DWC3 driver(per signal measurement result, it will be too
late to do it in xhci-plat.c or xhci.c).

Signed-off-by: Ran Wang <ran.wang_1@nxp.com>
Reviewed-by: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Frank Li <Frank.Li@nxp.com>
Link: https://lore.kernel.org/r/20240124152525.3910311-3-Frank.Li@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Documentation/devicetree/bindings/usb/snps,dwc3.yaml