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Subject: Re: [PATCH v5 0/2] ata: ahci_brcm: Fix use of BCM7216 reset
 controller
To:     Bjorn Helgaas <helgaas@kernel.org>,
        Jim Quinlan <james.quinlan@broadcom.com>
Cc:     Jim Quinlan <jim2101024@gmail.com>, linux-pci@vger.kernel.org,
        Nicolas Saenz Julienne <nsaenzjulienne@suse.de>,
        bcm-kernel-feedback-list@broadcom.com,
        Florian Fainelli <f.fainelli@gmail.com>,
        Hans de Goede <hdegoede@redhat.com>,
        Jens Axboe <axboe@kernel.dk>,
        Jim Quinlan <jquinlan@broadcom.com>,
        linux-arm-kernel@lists.infradead.org, linux-ide@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-rpi-kernel@lists.infradead.org,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Rob Herring <robh@kernel.org>,
        Amjad Ouled-Ameur <aouledameur@baylibre.com>,
        Philipp Zabel <p.zabel@pengutronix.de>
References: <20210428205319.GA429792@bjorn-Precision-5520>
From:   Florian Fainelli <f.fainelli@gmail.com>
Message-ID: <cd166f27-119d-a5ac-548e-175d79ddf49c@gmail.com>
Date:   Wed, 28 Apr 2021 14:03:00 -0700
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On 4/28/2021 1:53 PM, Bjorn Helgaas wrote:
> [+cc Amjad, Philipp: possible issue with 557acb3d2cd9 ("reset: make
> shared pulsed reset controls re-triggerable") below; report at
> https://lore.kernel.org/linux-ide/20210428200058.GA366202@bjorn-Precision-5520/]
> 
> On Wed, Apr 28, 2021 at 04:34:00PM -0400, Jim Quinlan wrote:
>> On Wed, Apr 28, 2021 at 4:01 PM Bjorn Helgaas <helgaas@kernel.org> wrote:
>>> On Fri, Mar 12, 2021 at 03:45:53PM -0500, Jim Quinlan wrote:
>>>> v5 -- Improved (I hope) commit description (Bjorn).
>>>>    -- Rnamed error labels (Krzyszt).
>>>>    -- Fixed typos.
>>>>
>>>> v4 -- does not rely on a pending commit, unlike v3.
>>>>
>>>> v3 -- discard commit from v2; instead rely on the new function
>>>>       reset_control_rearm provided in a recent commit [1] applied
>>>>       to reset/next.
>>>>    -- New commit to correct pcie-brcmstb.c usage of a reset controller
>>>>       to use reset/rearm verses deassert/assert.
>>>>
>>>> v2 -- refactor rescal-reset driver to implement assert/deassert rather than
>>>>       reset because the reset call only fires once per lifetime and we need
>>>>       to reset after every resume from S2 or S3.
>>>>    -- Split the use of "ahci" and "rescal" controllers in separate fields
>>>>       to keep things simple.
>>>>
>>>> v1 -- original
>>>>
>>>> Jim Quinlan (2):
>>>>   ata: ahci_brcm: Fix use of BCM7216 reset controller
>>>>   PCI: brcmstb: Use reset/rearm instead of deassert/assert
>>>>
>>>>  drivers/ata/ahci_brcm.c               | 46 +++++++++++++--------------
>>>>  drivers/pci/controller/pcie-brcmstb.c | 19 +++++++----
>>>>  2 files changed, 36 insertions(+), 29 deletions(-)
>>>
>>> Tripped over these errors while build testing with the .config below.
>>> This is on the pci/brcmstb branch from
>>> git://git.kernel.org/pub/scm/linux/kernel/git/lpieralisi/pci.git
>>>
>>> Dropping the pci/brcmstb branch while we get this figured out.  This will
>>> remove the following commits:
>>>
>>>   a24fd1d6469f ("PCI: brcmstb: Use reset/rearm instead of deassert/assert")
>>>   92b9cb55a9b6 ("ata: ahci_brcm: Fix use of BCM7216 reset controller")
>>>   b5d9209d5083 ("PCI: brcmstb: Fix error return code in brcm_pcie_probe()")
>>
>> Hi Bjorn,
>>
>> I believe the problem is that the commit
>>
>> 557acb3d2cd9c82de19f944f6cc967a347735385
>> "reset: make shared pulsed reset controls re-triggerable"
>>
>> defined reset_control_rearm() for the CONFIG_RESET_CONTROLLER=y  case
>> but forgot to define  an empty function for the unset case.  Your test
>> .config has this CONFIG unset.
>>
>> Would you like me to resubmit this with an additional commit that
>> fixes this?
> 
> The fix could be a patch along those lines, or it could be a Kconfig
> change that makes this config impossible.  I didn't look deeper to see
> what makes sense.  But I don't think the fix should be "manually avoid
> this configuration."
> 
> It looks like 557acb3d2cd9 ("reset: make shared pulsed reset controls
> re-triggerable") appeared in v5.11, so if a patch is the right thing,
> it should probably be marked for stable ("v5.11+").

All of the other reset controller API have inline stubs when
CONFIG_RESET_CONTROLLER is disabled, not having one for
reset_control_rearm() seems like an oversight (easy to make since if you
introduce the API you obviously needed it and did not consider the case
where it may not be available).

I agree this would be stable material.
-- 
Florian