Re: [PATCH v4] usb: xhci: allow imod-interval to be configurable

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On 05.12.2017 04:54, Adam Wallis wrote:
On 12/4/2017 9:15 PM, Chunfeng Yun wrote:
On Mon, 2017-12-04 at 09:27 -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-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 <chunfeng.yun@xxxxxxxxxxxx>
Signed-off-by: Adam Wallis <awallis@xxxxxxxxxxxxxx>
---
changes from v3:
   * Changed imod-interval to imod-interval-ns [Rob Herring/Chunfeng]
   * Changed "modulation" to "moderation" throughout patch [Mathias]
changes from v2:
   * Added PCI default value [Mathias]
   * Removed xhci-mtk.h from xhci-plat.c [Chunfeng Yun]
   * Removed MTK quirk from xhci-plat and moved logic to xhci-mtk [Chunfeng]
   * Updated bindings Documentation to use proper units [Rob Herring]
   * Added imod-interval description and example to MTK binding documentation
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/mediatek,mtk-xhci.txt | 2 ++
  Documentation/devicetree/bindings/usb/usb-xhci.txt          | 1 +
  drivers/usb/host/xhci-mtk.c                                 | 9 +++++++++
  drivers/usb/host/xhci-pci.c                                 | 3 +++
  drivers/usb/host/xhci-plat.c                                | 5 +++++
  drivers/usb/host/xhci.c                                     | 7 ++-----
  drivers/usb/host/xhci.h                                     | 2 ++
  7 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/Documentation/devicetree/bindings/usb/mediatek,mtk-xhci.txt b/Documentation/devicetree/bindings/usb/mediatek,mtk-xhci.txt
index 3059596..9ff5602 100644
--- a/Documentation/devicetree/bindings/usb/mediatek,mtk-xhci.txt
+++ b/Documentation/devicetree/bindings/usb/mediatek,mtk-xhci.txt
@@ -46,6 +46,7 @@ Optional properties:
   - pinctrl-names : a pinctrl state named "default" must be defined
   - pinctrl-0 : pin control group
  	See: Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt
+ - imod-interval-ns: default interrupt moderation interval is 5000ns
Example:
  usb30: usb@11270000 {
@@ -66,6 +67,7 @@ usb30: usb@11270000 {
  	usb3-lpm-capable;
  	mediatek,syscon-wakeup = <&pericfg>;
  	mediatek,wakeup-src = <1>;
+	imod-interval-ns = <10000>;
  };
2nd: dual-role mode with xHCI driver
diff --git a/Documentation/devicetree/bindings/usb/usb-xhci.txt b/Documentation/devicetree/bindings/usb/usb-xhci.txt
index ae6e484..969908d 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-ns: default interrupt moderation interval is 5000ns
Example:
  	usb@f0931000 {
diff --git a/drivers/usb/host/xhci-mtk.c b/drivers/usb/host/xhci-mtk.c
index b62a1d2..1cb2a8b 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) {
diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
index 7ef1274..4bcddd4 100644
--- a/drivers/usb/host/xhci-pci.c
+++ b/drivers/usb/host/xhci-pci.c
@@ -234,6 +234,9 @@ static int xhci_pci_setup(struct usb_hcd *hcd)
  	if (!xhci->sbrn)
  		pci_read_config_byte(pdev, XHCI_SBRN_OFFSET, &xhci->sbrn);
+ /* imod_interval is the interrupt moderation value in nanoseconds. */
+	xhci->imod_interval = 40000;
+
  	retval = xhci_gen_setup(hcd, xhci_pci_quirks);
  	if (retval)
  		return retval;
diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
index 09f164f..6f03830 100644
--- a/drivers/usb/host/xhci-plat.c
+++ b/drivers/usb/host/xhci-plat.c
@@ -269,6 +269,11 @@ 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 moderation value in nanoseconds. */
+	xhci->imod_interval = 40000;
+	device_property_read_u32(sysdev, "imod-interval-ns",
+				 &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");
s/modulation/moderation

Mathias said there was no need to change the existing modulation strings - only
the ones that I had added.

Baolu is working on a cleanup patch that removes debug messages that became
useless with debugfs and proper tracing support, including this line.

Less conflicts to resolve for me if we don't change this.



  	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;
+
No need a blank line

If this patch goes through another version, I will remove this line

If Rob Acks this version I'll apply it and remove that blank line.

-Mathias
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