linux-kernel - Re: [PATCH v1 0/5] Enable fw

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Date:   Thu, 28 Jan 2021 09:27:57 -0800
From:   Saravana Kannan <saravanak@...gle.com>
To:     Jon Hunter <jonathanh@...dia.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Android Kernel Team <kernel-team@...roid.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Jisheng Zhang <Jisheng.Zhang@...aptics.com>,
        Kevin Hilman <khilman@...libre.com>,
        John Stultz <john.stultz@...aro.org>,
        Nicolas Saenz Julienne <nsaenzjulienne@...e.de>,
        Marc Zyngier <maz@...nel.org>,
        linux-tegra <linux-tegra@...r.kernel.org>
Subject: Re: [PATCH v1 0/5] Enable fw_devlink=on by default

On Thu, Jan 28, 2021 at 7:03 AM Jon Hunter <jonathanh@...dia.com> wrote:
>
>
> On 14/01/2021 16:56, Jon Hunter wrote:
> >
> > On 14/01/2021 16:47, Saravana Kannan wrote:
> >
> > ...
> >
> >>> Yes this is the warning shown here [0] and this is coming from
> >>> the 'Generic PHY stmmac-0:00' device.
> >>
> >> Can you print the supplier and consumer device when this warning is
> >> happening and let me know? That'd help too. I'm guessing the phy is
> >> the consumer.
> >
> >
> > Sorry I should have included that. I added a print to dump this on
> > another build but failed to include here.
> >
> > WARNING KERN Generic PHY stmmac-0:00: supplier 2200000.gpio (status 1)
> >
> > The status is the link->status and looks like the supplier is the
> > gpio controller. I have verified that the gpio controller is probed
> > before this successfully.
> >
> >> So the warning itself isn't a problem -- it's not breaking anything or
> >> leaking memory or anything like that. But the device link is jumping
> >> states in an incorrect manner. With enough context of this code (why
> >> the device_bind_driver() is being called directly instead of going
> >> through the normal probe path), it should be easy to fix (I'll just
> >> need to fix up the device link state).
> >
> > Correct, the board seems to boot fine, we just get this warning.
>

Hi Jon,

>
> Have you had chance to look at this further?

No, I feel like I'm just spending all my "upstream time" just
replying to email :)

>
> The following does appear to avoid the warning, but I am not sure if
> this is the correct thing to do ...
>
> index 9179825ff646..095aba84f7c2 100644
> --- a/drivers/base/dd.c
> +++ b/drivers/base/dd.c
> @@ -456,6 +456,10 @@ int device_bind_driver(struct device *dev)
>  {
>         int ret;
>
> +       ret = device_links_check_suppliers(dev);
> +       if (ret)
> +               return ret;
> +

Yeah I knew calling this function (where device_bind_driver() was
called) would take away the warning, but I first want to understand
why the caller wasn't going through the typical device/driver probe
path before I started adding more of the typical device/driver probe
path code in. I don't want to add in code they might have been
explicitly trying to avoid.

Also, once you do this, you'll need the reverse of this (deleting
links/unsetting state change) somewhere.

Also, device_bind_driver() is used in a bunch of places. Need to check
if it's right to call device_links_check_suppliers() in those
instances.

Feel free to look at those items above. I'll try to get to this once I
take care of the "my device is not working!" issues.

Thanks,
Saravana

>         ret = driver_sysfs_add(dev);
>         if (!ret)
>                 driver_bound(dev);
>