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.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'drivers/usb/host/xhci.h') diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h index 7c8781758cea..96099a245c69 100644 --- a/drivers/usb/host/xhci.h +++ b/drivers/usb/host/xhci.h @@ -1717,6 +1717,8 @@ struct xhci_hcd { u8 max_interrupters; u8 max_ports; u8 isoc_threshold; + /* imod_interval in ns (I * 250ns) */ + u32 imod_interval; int event_ring_max; /* 4KB min, 128MB max */ int page_size; -- cgit