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

[Mathias Nyman <mathias.nyman-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>]

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-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>
>>> Signed-off-by: Adam Wallis <awallis-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.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@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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