Re: [PATCH v3 3/3] usb: dwc: host: add xhci_plat_priv quirk XHCI_SKIP_PHY_INIT

[Pavan Kondeti <quic_pkondeti@quicinc.com>]

Hi Mathias,

On Wed, Apr 06, 2022 at 03:18:17PM +0300, Mathias Nyman wrote:
> On 6.4.2022 14.01, Pavan Kondeti wrote:
> > Hi Mathias,
> > 
> > On Wed, Apr 06, 2022 at 01:52:56PM +0300, Mathias Nyman wrote:
> >> Hi
> >>
> >> Sorry about the delayed response.
> >>
> >>
> >> On 6.4.2022 9.25, Pavan Kondeti wrote:
> >>> Hi Heikki/Mathias,
> >>>
> >>> On Mon, Apr 04, 2022 at 01:55:16PM +0530, Pavan Kondeti wrote:
> >>>> Hi Heikki,
> >>>>
> >>>> On Thu, Mar 31, 2022 at 02:16:53PM +0300, Heikki Krogerus wrote:
> >>>>> On Wed, Mar 30, 2022 at 08:47:34PM +0300, Mathias Nyman wrote:
> >>>>>> On 29.3.2022 12.18, Sandeep Maheswaram (Temp) wrote:
> >>>>>>> Hi Mathias,Heikki
> >>>>>>>
> >>>>>>> On 3/25/2022 9:08 PM, Heikki Krogerus wrote:
> >>>>>>>> On Fri, Mar 25, 2022 at 04:33:27PM +0200, Mathias Nyman wrote:
> >>>>>>>>> On 25.3.2022 13.27, Heikki Krogerus wrote:
> >>>>>>>>>> On Fri, Mar 25, 2022 at 12:36:22AM +0200, Mathias Nyman wrote:
> >>>>>>>>>>> On 24.3.2022 14.27, Heikki Krogerus wrote:
> >>>>>>>>>>>> On Thu, Mar 24, 2022 at 12:07:11PM +0530, Sandeep Maheswaram wrote:
> >>>>>>>>>>>>> Currently the phy init is done from dwc3 and also xhci which makes the
> >>>>>>>>>>>>> runtime_usage value 2 for the phy which causes issue during runtime
> >>>>>>>>>>>>> suspend. When we run the below command the runtime_status still shows
> >>>>>>>>>>>>> active.
> >>>>>>>>>>>>> echo auto > /sys/bus/platform/devices/88e3000.phy/power/control
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> dwc3 manages PHY by own DRD driver, so skip the management by
> >>>>>>>>>>>>> HCD core by setting this quirk.
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> Signed-off-by: Sandeep Maheswaram <quic_c_sanm@quicinc.com>
> >>>>>>>>>>>>> ---
> >>>>>>>>>>>>>   drivers/usb/dwc3/host.c | 13 +++++++++++++
> >>>>>>>>>>>>>   1 file changed, 13 insertions(+)
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> diff --git a/drivers/usb/dwc3/host.c b/drivers/usb/dwc3/host.c
> >>>>>>>>>>>>> index eda8719..d4fcf06 100644
> >>>>>>>>>>>>> --- a/drivers/usb/dwc3/host.c
> >>>>>>>>>>>>> +++ b/drivers/usb/dwc3/host.c
> >>>>>>>>>>>>> @@ -13,6 +13,12 @@
> >>>>>>>>>>>>>   #include <linux/platform_device.h>
> >>>>>>>>>>>>>     #include "core.h"
> >>>>>>>>>>>>> +#include <linux/usb/xhci-plat.h>
> >>>>>>>>>>>>> +#include <linux/usb/xhci-quirks.h>
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> +static const struct xhci_plat_priv xhci_plat_dwc3_xhci = {
> >>>>>>>>>>>>> +    .quirks = XHCI_SKIP_PHY_INIT,
> >>>>>>>>>>>>> +};
> >>>>>>>>>>>>>     static void dwc3_host_fill_xhci_irq_res(struct dwc3 *dwc,
> >>>>>>>>>>>>>                       int irq, char *name)
> >>>>>>>>>>>>> @@ -122,6 +128,13 @@ int dwc3_host_init(struct dwc3 *dwc)
> >>>>>>>>>>>>>           }
> >>>>>>>>>>>>>       }
> >>>>>>>>>>>>>   +    ret = platform_device_add_data(xhci, &xhci_plat_dwc3_xhci,
> >>>>>>>>>>>>> +            sizeof(xhci_plat_dwc3_xhci));
> >>>>>>>>>>>>> +    if (ret) {
> >>>>>>>>>>>>> +        dev_err(dwc->dev, "failed to add data to xHCI\n");
> >>>>>>>>>>>>> +        goto err;
> >>>>>>>>>>>>> +    }
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>>       ret = platform_device_add(xhci);
> >>>>>>>>>>>>>       if (ret) {
> >>>>>>>>>>>>>           dev_err(dwc->dev, "failed to register xHCI device\n");
> >>>>>>>>>>>> I think you should just use device property:
> >>>>>>>>>>>>
> >>>>>>>>>>> This was suggested in an earlier series, but was rejected as it also added
> >>>>>>>>>>> the property as a device tree parameter.
> >>>>>>>>>>>
> >>>>>>>>>>> I think adding more device properties can be messy in the long run, especially if we
> >>>>>>>>>>> need to add them for many of the existing xhci quirks.
> >>>>>>>>>>> We also end up with a mix where some device properties are listed as device tree
> >>>>>>>>>>> parameters, and some not.
> >>>>>>>>>>>
> >>>>>>>>>>> Defining xhci quirks and platform data structure in headers shared with dwc3 and cdns3
> >>>>>>>>>>> allow those drivers to easily set any existing xhci quirk, or other possible optional
> >>>>>>>>>>> callbacks.
> >>>>>>>>>>>
> >>>>>>>>>>> cdns3 driver is already doing this, but it includes the full xhci.h header.
> >>>>>>>>>>> This series cleans up that a bit so cdns3 will only include xhci quirk bits and
> >>>>>>>>>>> platform data structure.
> >>>>>>>>>>>
> >>>>>>>>>>> On the downside we add a couple xhci related header files to include/linux/usb/
> >>>>>>>>>>> Let me know if you see any other issues I missed with this approach.
> >>>>>>>>>> The problem here is that these drivers are now coupled together, and
> >>>>>>>>>> that should not be taken lightly. We have a dependency hell in our
> >>>>>>>>>> hands with a lot of drivers, and the culprit is always platform data.
> >>>>>>>>>>
> >>>>>>>>>> Build-in device properties may be messy, but I would still say they
> >>>>>>>>>> are less messy than those quirk flags - you got to admit, they are a
> >>>>>>>>>> mess. The benefit from build-in properties is in any case the fact
> >>>>>>>>>> that they remove the need to couple these drivers together.
> >>>>>>>>> Agree, quirk bits are messy. Any suggestion that would work with
> >>>>>>>>> PCI xHCI devices, devicetree, and "pure" platform devices?
> >>>>>>>> I think xHCI driver should always be able to rely on being able to
> >>>>>>>> read this kind of information from the fwnode. If there is no actual
> >>>>>>>> firmware node (DT or ACPI), or if it's missing some information, the
> >>>>>>>> glue driver needs to populate software node for the xHCI.
> >>>>>>>>
> >>>>>>>> Right now I just want to avoid having to pass the quirks using
> >>>>>>>> platform data from drivers such as drivers/usb/cdns3/host.c and
> >>>>>>>> drivers/usb/dwc3/host.c to xHCI.
> >>>>>>>>
> >>>>>>>> One way we could do that is by defining compatibility ID for both of
> >>>>>>>> them that we provide using a single device property (like I guess DT
> >>>>>>>> does). Then based on that compatibility ID, xhci-plat.c can set the
> >>>>>>>> actual "static" quirk flags. That we could already do easily. How
> >>>>>>>> would that sound to you?
> >>>>>>
> >>>>>> Sounds good. 
> >>>>>>
> >>>>>>>
> >>>>>>> This was my previous patch where I was using device tree property. Should we go ahead with this approach?
> >>>>>>>
> >>>>>>> https://patchwork.kernel.org/project/linux-arm-msm/cover/1636353710-25582-1-git-send-email-quic_c_sanm@quicinc.com/
> >>>>>>>
> >>>>>>> Any further changes to this ?
> >>>>>>
> >>>>>> By dropping the DT part of that series we get a similar built-in device property
> >>>>>> solution as Heikki initially suggested.
> >>>>>>
> >>>>>> How about adding the compatibility ID device property that was just suggested?
> >>>>>> Then matching the Id in xhci-plat.c against a static table containing Ids and
> >>>>>> xhci_plat_priv structures, with the needed quirks for dwc3.
> >>>>>
> >>>>> There was a comment from Pavan. Is it still possible to get this
> >>>>> detail from DT?
> >>>>> I guess that would still be ideal, right?
> >>>>>
> >>>> I was suggesting if we can have device tree param like the patch sandeep
> >>>> pointed out.
> >>>>
> >>>> How would adding a compatible index to usb_xhci_of_match[] would work
> >>>> actually? I ask this because, dwc3/host.c creates platform device and
> >>>> it is not associated with any of_node, so of_driver_match_device() called
> >>>> from platform bus match method does not work. one way to achieve this would
> >>>> be by matching against sysdev. Something like below. Is it acceptible?
> >>>>
> >>>> diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
> >>>> index 649ffd8..bd5d055 100644
> >>>> --- a/drivers/usb/host/xhci-plat.c
> >>>> +++ b/drivers/usb/host/xhci-plat.c
> >>>> @@ -126,6 +126,10 @@ static const struct xhci_plat_priv xhci_plat_brcm = {
> >>>>  	.quirks = XHCI_RESET_ON_RESUME,
> >>>>  };
> >>>>  
> >>>> +static const struct xhci_plat_priv xhci_plat_dwc3 = {
> >>>> +	.quirks = XHCI_SKIP_PHY_INIT,
> >>>> +};
> >>>> +
> >>>>  static const struct of_device_id usb_xhci_of_match[] = {
> >>>>  	{
> >>>>  		.compatible = "generic-xhci",
> >>>> @@ -167,6 +171,9 @@ static const struct of_device_id usb_xhci_of_match[] = {
> >>>>  	}, {
> >>>>  		.compatible = "brcm,bcm7445-xhci",
> >>>>  		.data = &xhci_plat_brcm,
> >>>> +	}, {
> >>>> +		.compatible = "snps,dwc3",
> >>>> +		.data = &xhci_plat_dwc3,
> >>>>  	},
> >>
> >> Isn't there a risk that xhci-plat now binds to the parent dwc3 device?
> >> competing with the similar of_match_table entry created in drivers/usb/dwc3/core.c
> > 
> > Sill of me. Yes, it does not work. Thanks for pointing it out.
> > 
> >>
> >>>>  	{},
> >>>>  };
> >>>> @@ -274,6 +281,15 @@ static int xhci_plat_probe(struct platform_device *pdev)
> >>>>  	else
> >>>>  		priv_match = dev_get_platdata(&pdev->dev);
> >>>>  
> >>>> +	/* allow private data mapping with the sysdev compatible */
> >>>> +	if (!priv_match) {
> >>>> +		struct of_device_id *match;
> >>>> +
> >>>> +		match = of_match_device(usb_xhci_of_match, sysdev);
> >>>> +		if (match)
> >>>> +			priv_match = match->data;
> >>>> +	}
> >>>> +
> >>>>  	if (priv_match) {
> >>>>  		priv = hcd_to_xhci_priv(hcd);
> >>>>  		/* Just copy data for now */
> >>>>
> >>>>> I have another question. Can't we now just assume that if the sysdev
> >>>>> is the parent (or grandparent), then the phy initialization should
> >>>>> always be skipped? In that case we could just do something like this:
> >>>>>
> >>>>> diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
> >>>>> index 649ffd861b44e..1018b33488046 100644
> >>>>> --- a/drivers/usb/host/xhci-plat.c
> >>>>> +++ b/drivers/usb/host/xhci-plat.c
> >>>>> @@ -212,8 +212,12 @@ static int xhci_plat_probe(struct platform_device *pdev)
> >>>>>  #endif
> >>>>>         }
> >>>>>  
> >>>>> -       if (!sysdev)
> >>>>> +       if (sysdev) {
> >>>>> +               if (sysdev != &pdev->dev)
> >>>>> +                       hcd->skip_phy_initialization = 1;
> >>>>> +       } else {
> >>>>>                 sysdev = &pdev->dev;
> >>>>> +       }
> >>>>>  
> >>>>>         if (WARN_ON(!sysdev->dma_mask))
> >>>>>                 /* Platform did not initialize dma_mask */
> >>>>>
> >>>>>
> >>>>> I did not go through all the drivers that carefully, so I may have
> >>>>> missed something, but it looks like the only drivers that can have the
> >>>>> sysdev as the parent or grandparent are cdns3 and dwc3.
> >>>>>
> >>>> I cross checked and these are two drivers that are creating xhci-plat device.
> >>>> So this patch would definitely work. However I am not sure in future if any
> >>>> device created via device tree would want to use this feature. For now,
> >>>> it looks good. It Mathias, Do you see any problem with this approach?
> >>>>
> >>
> >> Would work for now but seems like a risk to assume this would hold for all future
> >> xhci platform devices. 
> >>
> > Agree that it may break in future for other drivers.
> > 
> >>>
> >>> Can you please provide your suggestions on this? We have discussed about
> >>> 3 approaches here other than the whole platform data refactoring done.
> >>>
> >>> (1) Introduce a new dT property and expect dwc3/host.c to set this property
> >>> to skip the phy initialization.
> >>
> >> Adding one more device property to swnode in dwc3/host.c starts
> >> to look like the best option for now even if it didn't appeal initially.
> >>
> >> The place creating the xhci platform device should have best info on what properties
> >> are needed for the platform device.
> >>
> >> So this would be just like Heikki's first suggestion, or Sandeep's patches 2/3 and 3/3 in:
> >> https://patchwork.kernel.org/project/linux-arm-msm/cover/1636353710-25582-1-git-send-email-quic_c_sanm@quicinc.com/
> >> but without the devicetree binding documentation part.
> >>
> > Why do you say devicetree binding doc is not needed in this case? Possible
> > that xhci-plat's device can be coming from dT and this param is passed to
> > skip initialization of PHY.
> 
> Adding it is fine by me. It was rejected earlier by Rob Herring
> 
> But we can live without it.
> In dwc3 and cdns3 "pure" platform case we add the device property when
> creating the device.
> 
> In dT case we should have a compatible entry, and we can add a matching
> entry in usb_xhci_of_match[] which sets the needed quirk.
> 
Got it. Thanks for the explanation. We can go with Sandeep's patches 2/3 and
3/3 which add dT param and can be set by the dwc3/host.c

Thanks,
Pavan