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 --- drivers/usb/host/xhci-mtk.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'drivers/usb/host/xhci-mtk.c') diff --git a/drivers/usb/host/xhci-mtk.c b/drivers/usb/host/xhci-mtk.c index b62a1d23244b..1cb2a8ba2de5 100644 --- a/drivers/usb/host/xhci-mtk.c +++ b/drivers/usb/host/xhci-mtk.c @@ -674,6 +674,15 @@ static int xhci_mtk_probe(struct platform_device *pdev) xhci = hcd_to_xhci(hcd); xhci->main_hcd = hcd; + + /* + * imod_interval is the interrupt moderation value in nanoseconds. + * The increment interval is 8 times as much as that defined in + * the xHCI spec on MTK's controller. + */ + xhci->imod_interval = 5000; + device_property_read_u32(dev, "imod-interval-ns", &xhci->imod_interval); + xhci->shared_hcd = usb_create_shared_hcd(driver, dev, dev_name(dev), hcd); if (!xhci->shared_hcd) { -- cgit v1.2.3