linux-kernel - Re: [PATCH RESEND V2 3/6] platform/x86/intel: Move intel

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Date:   Wed, 22 Dec 2021 13:57:07 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Hans de Goede <hdegoede@...hat.com>
Cc:     david.e.box@...ux.intel.com, lee.jones@...aro.org,
        bhelgaas@...gle.com, andriy.shevchenko@...ux.intel.com,
        srinivas.pandruvada@...el.com, mgross@...ux.intel.com,
        linux-kernel@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        linux-pci@...r.kernel.org, Mark Gross <markgross@...nel.org>
Subject: Re: [PATCH RESEND V2 3/6] platform/x86/intel: Move intel_pmt from
 MFD to Auxiliary Bus

On Tue, Dec 21, 2021 at 07:38:38PM +0100, Hans de Goede wrote:
> Hi,
> 
> On 12/21/21 19:16, David E. Box wrote:
> > On Tue, 2021-12-21 at 18:04 +0100, Hans de Goede wrote:
> >> Hi,
> >>
> >> On 12/21/21 17:54, Greg KH wrote:
> >>> On Tue, Dec 21, 2021 at 08:44:57AM -0800, David E. Box wrote:
> >>>> On Tue, 2021-12-21 at 08:38 +0100, Greg KH wrote:
> >>>>> On Wed, Dec 08, 2021 at 01:30:06PM -0800, David E. Box wrote:
> >>>>>> On Wed, 2021-12-08 at 20:21 +0100, Greg KH wrote:
> >>>>>>> On Wed, Dec 08, 2021 at 11:09:48AM -0800, David E. Box wrote:
> >>>>>>>> On Wed, 2021-12-08 at 19:11 +0100, Greg KH wrote:
> >>>>>>>>> On Wed, Dec 08, 2021 at 09:47:26AM -0800, David E. Box wrote:
> >>>>>>>>>> On Wed, 2021-12-08 at 17:22 +0100, Greg KH wrote:
> >>>>>>>>>>> On Tue, Dec 07, 2021 at 05:50:12PM -0800, David E. Box
> >>>>>>>>>>> wrote:
> >>>>>>>>>>>> +static struct pci_driver intel_vsec_pci_driver = {
> >>>>>>>>>>>> +       .name = "intel_vsec",
> >>>>>>>>>>>> +       .id_table = intel_vsec_pci_ids,
> >>>>>>>>>>>> +       .probe = intel_vsec_pci_probe,
> >>>>>>>>>>>> +};
> >>>>>>>>>>>
> >>>>>>>>>>> So when the PCI device is removed from the system you leak
> >>>>>>>>>>> resources and
> >>>>>>>>>>> have dangling devices?
> >>>>>>>>>>
> >>>>>>>>>> No.
> >>>>>>>>>>
> >>>>>>>>>>> Why no PCI remove driver callback?
> >>>>>>>>>>
> >>>>>>>>>> After probe all resources are device managed. There's nothing
> >>>>>>>>>> to
> >>>>>>>>>> explicitly clean up. When
> >>>>>>>>>> the
> >>>>>>>>>> PCI
> >>>>>>>>>> device is removed, all aux devices are automatically removed.
> >>>>>>>>>> This
> >>>>>>>>>> is the case for the SDSi
> >>>>>>>>>> driver
> >>>>>>>>>> as well.
> >>>>>>>>>
> >>>>>>>>> Where is the "automatic cleanup" happening?  As this pci driver
> >>>>>>>>> is
> >>>>>>>>> bound
> >>>>>>>>> to the PCI device, when the device is removed, what is called in
> >>>>>>>>> this
> >>>>>>>>> driver to remove the resources allocated in the probe callback?
> >>>>>>>>>
> >>>>>>>>> confused,
> >>>>>>>>
> >>>>>>>> devm_add_action_or_reset(&pdev->dev, intel_vsec_remove_aux,
> >>>>>>>> auxdev)
> >>>>>>>
> >>>>>>> Wow that is opaque.  Why not do it on remove instead?
> >>>>>>
> >>>>>> This code is common for auxdev cleanup. AFAICT most auxiliary bus code
> >>>>>> is
> >>>>>> done by drivers that have
> >>>>>> some other primary function. They clean up their primary function
> >>>>>> resources
> >>>>>> in remove, but they
> >>>>>> clean up the auxdev using the method above. In this case the sole
> >>>>>> purpose of
> >>>>>> this driver is to
> >>>>>> create the auxdev. There are no other resources beyond what the auxdev
> >>>>>> is
> >>>>>> using.
> >>>>>>
> >>>>>> Adding runtime pm to the pci driver will change this. Remove will be
> >>>>>> needed
> >>>>>> then.
> >>>>>
> >>>>> And who will notice that being required when that happens?
> >>>>>
> >>>>> Why is there no runtime PM for this driver?  Do you not care about power
> >>>>> consumption?  :)
> >>>>
> >>>> Of course. :)
> >>>>
> >>>> There's a backlog of patches waiting for this series. One adds support for
> >>>> the
> >>>> telemetry device (an auxdev) on the DG2 GPU. This device requires runtime
> >>>> pm in
> >>>> order for the slot to go D3. But this also requires changes to the
> >>>> telemetry
> >>>> driver in order for runtime pm to be handled correctly. These and other
> >>>> patches,
> >>>> including a series to have all current aux drivers use the new drvdata
> >>>> helpers,
> >>>> are waiting for this.
> >>>
> >>> I can take the aux driver drvdata patch now, through my tree, if you
> >>> want, no need to make it wait for this tiny driver.
> >>>
> >>> Feel free to send it independant of the existing patchset, and with the
> >>> cleanup patches at the same time, should be quite easy to get merged.
> >>
> >> If you're going to take that one, can you perhaps take patches
> >> 1-3 for 5.17 through your tree as well (patch 3 depends on 2/it) ?
> >>
> >> Note there is a v4 of this series, see please use that :)
> >>
> >> I assume the follow up patches are also going to need patch 3
> >> (the actual conversion of the driver to aux-bus).
> > 
> > Yes.
> > 
> >>
> >> Here is my Ack for the pdx86 bits in patch 3:
> >>
> >> Acked-by: Hans de Goede <hdegoede@...hat.com>
> >>
> >> And patch 1 and 3 also have acks from the PCI resp. MFD subsys maintainers,
> >> so I guess taking this all upstream through your tree is fine.
> > 
> > Should I send 1-3 plus the drvdata cleanup patches I have to Grep? V5?
> 
> No there is no need for that v4 is fine, since no changes have been
> requested there is no need to send out a new version.

I've taken patches 1-3 of this series now, thanks.

greg k-h