On Tue, Nov 28, 2017 at 12:11:46PM -0500, Adam Wallis wrote: > 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", 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. > > Backwards compatibility is maintained for MTK_HOSTS through the quirk > bit, however, imod_interval should be pushed into device tree at a > future point and this quirk should be removed from xhci_plat_probe > > Signed-off-by: Adam Wallis <awallis@xxxxxxxxxxxxxx> > --- > Documentation/devicetree/bindings/usb/usb-xhci.txt | 1 + > drivers/usb/host/xhci-plat.c | 15 +++++++++++++++ > drivers/usb/host/xhci.c | 7 ++----- > drivers/usb/host/xhci.h | 2 ++ > 4 files changed, 20 insertions(+), 5 deletions(-) > > diff --git a/Documentation/devicetree/bindings/usb/usb-xhci.txt b/Documentation/devicetree/bindings/usb/usb-xhci.txt > index ae6e484..3998459 100644 > --- a/Documentation/devicetree/bindings/usb/usb-xhci.txt > +++ b/Documentation/devicetree/bindings/usb/usb-xhci.txt > @@ -29,6 +29,7 @@ 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: IMOD_INTERVAL in nano-seconds. Default is 40000 Needs a unit suffix as defined in property-units.txt. Rob -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html