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>
---
changes from v1:
* Removed device_property_read_u32() per suggestion from greg k-h
* Used ER_IRQ_INTERVAL_MASK in place of (u16) cast
Documentation/devicetree/bindings/usb/usb-xhci.txt | 1 +
drivers/usb/host/xhci-plat.c | 13 +++++++++++++
drivers/usb/host/xhci.c | 7 ++-----
drivers/usb/host/xhci.h | 2 ++
4 files changed, 18 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
Example:
usb@f0931000 {
diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
index 09f164f..3c63de1 100644
--- a/drivers/usb/host/xhci-plat.c
+++ b/drivers/usb/host/xhci-plat.c
@@ -23,6 +23,7 @@
#include "xhci-plat.h"
#include "xhci-mvebu.h"
#include "xhci-rcar.h"
+#include "xhci-mtk.h"
static struct hc_driver __read_mostly xhci_plat_hc_driver;
@@ -269,6 +270,18 @@ static int xhci_plat_probe(struct platform_device *pdev)
if (device_property_read_bool(&pdev->dev, "quirk-broken-port-ped"))
xhci->quirks |= XHCI_BROKEN_PORT_PED;
+ /*
+ * imod_interval is the interrupt modulation value in nanoseconds.
+ * The increment interval is 8 times as much as that defined in
+ * the xHCI spec on MTK's controller. This quirk check exists to provide
+ * backwards compatibility, however, this should be pushed into
+ * the device tree files at some point in the future and
+ * checking the quirk should be removed from xhci_plat_probe.
+ */
+ xhci->imod_interval = xhci->quirks & XHCI_MTK_HOST ? 5000 : 40000;
+
+ device_property_read_u32(sysdev, "imod-interval", &xhci->imod_interval);
+
hcd->usb_phy = devm_usb_get_phy_by_phandle(sysdev, "usb-phy", 0);
if (IS_ERR(hcd->usb_phy)) {
ret = PTR_ERR(hcd->usb_phy);
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 2424d30..0b7755b 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -586,11 +586,8 @@ int xhci_run(struct usb_hcd *hcd)
"// Set the interrupt modulation register");
temp = readl(&xhci->ir_set->irq_control);
temp &= ~ER_IRQ_INTERVAL_MASK;
- /*
- * the increment interval is 8 times as much as that defined
- * in xHCI spec on MTK's controller
- */
- temp |= (u32) ((xhci->quirks & XHCI_MTK_HOST) ? 20 : 160);
+ temp |= (xhci->imod_interval / 250) & ER_IRQ_INTERVAL_MASK;
+
writel(temp, &xhci->ir_set->irq_control);
/* Set the HCD state before we enable the irqs */
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 99a014a..2a4177b 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;
--
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