linux-kernel - Re: [PATCH v1] driver core: Fix handling of fw

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Message-ID: <CAGETcx9r_t0AWVaTt5hk9s6Tti0UcNAersjXCJ_A04yJKNPtDA@mail.gmail.com>
Date:   Thu, 16 Apr 2020 11:25:47 -0700
From:   Saravana Kannan <saravanak@...gle.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Marek Szyprowski <m.szyprowski@...sung.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Android Kernel Team <kernel-team@...roid.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1] driver core: Fix handling of fw_devlink=permissive

On Tue, Mar 31, 2020 at 12:29 AM Greg Kroah-Hartman
<gregkh@...uxfoundation.org> wrote:
>
> On Mon, Mar 30, 2020 at 11:18:01PM -0700, Saravana Kannan wrote:
> > On Mon, Mar 30, 2020 at 10:43 PM Marek Szyprowski
> > <m.szyprowski@...sung.com> wrote:
> > >
> > > Hi,
> > >
> > > On 2020-03-31 04:28, Saravana Kannan wrote:
> > > > When commit 8375e74f2bca ("driver core: Add fw_devlink kernel
> > > > commandline option") added fw_devlink, it didn't implement "permissive"
> > > > mode correctly.
> > > >
> > > > That commit got the device links flags correct to make sure unprobed
> > > > suppliers don't block the probing of a consumer. However, if a consumer
> > > > is waiting for mandatory suppliers to register, that could still block a
> > > > consumer from probing.
> > > >
> > > > This commit fixes that by making sure in permissive mode, all suppliers
> > > > to a consumer are treated as a optional suppliers. So, even if a
> > > > consumer is waiting for suppliers to register and link itself (using the
> > > > DL_FLAG_SYNC_STATE_ONLY flag) to the supplier, the consumer is never
> > > > blocked from probing.
> > > >
> > > > Fixes: 8375e74f2bca ("driver core: Add fw_devlink kernel commandline option")
> > > > Reported-by: Marek Szyprowski <m.szyprowski@...sung.com>
> > > > Signed-off-by: Saravana Kannan <saravanak@...gle.com>
> > > > ---
> > > > Hi Marek,
> > > >
> > > > If you pull in this patch and then add back in my patch that created the
> > > > boot problem for you, can you see if that fixes the boot issue for you?
> > >
> > > Indeed, this fixes booting on my Raspberry Pi3/4 boards with linux
> > > next-20200327. Thanks! :)
> >
> > Hi Marek,
> >
> > Thanks for testing, but I'm not able to find the tag next-20200327. I
> > can only find next-20200326 and next-20200330. I was just trying to
> > make sure that next-20200327 doesn't have the revert Greg did. I'm
> > guessing you meant next-20200326?
> >
> > > Tested-by: Marek Szyprowski <m.szyprowski@...sung.com>
> >
> > Thanks!
> >
> > Greg,
> >
> > Can you pull in my fix and then revert the revert?
>
> After 5.7-rc1 is out I will, thanks.

Hi Greg,

Just to clarify, this patch is a bug fix and I think this patch should
go into all the stable branches that support fw_devlink.

The only risky change that you needed to wait on for 5.7-rc1 is the
patch [1] that sets fw_devlink=permissive by default. Well, a revert
of the revert of [1].

[1] - https://lore.kernel.org/lkml/20200321210305.28937-1-saravanak@google.com/

Thanks,
Saravana