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

[Adam Wallis]

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 at mediatek.com>
>> Signed-off-by: Adam Wallis <awallis at codeaurora.org>
>> ---
>> 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 at 11270000 {
>> @@ -66,6 +67,7 @@ usb30: usb at 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 at 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.

> 
>>  	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

> 
>>  	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;
> 
> Thanks
> 
> 


-- 
Adam Wallis
Qualcomm Datacenter Technologies as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project.