From ab725cbec3e83dc29cc00b733bd26063b588fa98 Mon Sep 17 00:00:00 2001 From: Adam Wallis Date: Fri, 8 Dec 2017 17:59:13 +0200 Subject: usb: xhci: allow imod-interval to be configurable The xHCI driver currently has the IMOD set to 160, which translates to an IMOD interval of 40,000ns (160 * 250)ns Commit 0cbd4b34cda9 ("xhci: mediatek: support MTK xHCI host controller") introduced a QUIRK for the MTK platform to adjust this interval to 20, which translates to an IMOD interval of 5,000ns (20 * 250)ns. This is due to the fact that the MTK controller IMOD interval is 8 times as much as defined in xHCI spec. Instead of adding more quirk bits for additional platforms, this patch introduces the ability for vendors to set the IMOD_INTERVAL as is optimal for their platform. By using device_property_read_u32() on "imod-interval-ns", the IMOD INTERVAL can be specified in nano seconds. If no interval is specified, the default of 40,000ns (IMOD=160) will be used. No bounds checking has been implemented due to the fact that a vendor may have violated the spec and would need to specify a value outside of the max 8,000 IRQs/second limit specified in the xHCI spec. Tested-by: Chunfeng Yun Reviewed-by: Rob Herring Signed-off-by: Adam Wallis Signed-off-by: Mathias Nyman Signed-off-by: Greg Kroah-Hartman --- Documentation/devicetree/bindings/usb/usb-xhci.txt | 1 + 1 file changed, 1 insertion(+) (limited to 'Documentation/devicetree/bindings/usb/usb-xhci.txt') diff --git a/Documentation/devicetree/bindings/usb/usb-xhci.txt b/Documentation/devicetree/bindings/usb/usb-xhci.txt index a53107132cc3..e2ea59bbca93 100644 --- a/Documentation/devicetree/bindings/usb/usb-xhci.txt +++ b/Documentation/devicetree/bindings/usb/usb-xhci.txt @@ -31,6 +31,7 @@ Optional properties: - usb2-lpm-disable: indicate if we don't want to enable USB2 HW LPM - usb3-lpm-capable: determines if platform is USB3 LPM capable - quirk-broken-port-ped: set if the controller has broken port disable mechanism + - imod-interval-ns: default interrupt moderation interval is 5000ns Example: usb@f0931000 { -- cgit v1.2.3