From: m.szyprowski@samsung•com (Marek Szyprowski)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v5 RESEND 4/5] ARM: amba: Move reading of periphid to amba_match()
Date: Tue, 12 Apr 2016 16:09:02 +0200 [thread overview]
Message-ID: <570D017E.7060105@samsung.com> (raw)
In-Reply-To: <CAPDyKFpjTOhmG69x=EP=jje76C1ijjh0m_N8PrJ3yxqRq3HFiw@mail.gmail.com>
Hi Ulf,
On 2016-04-12 13:39, Ulf Hansson wrote:
> - trimmed cc list
>
> On 2 March 2016 at 11:16, Ulf Hansson <ulf.hansson@linaro•org> wrote:
>> On 17 February 2016 at 21:08, Russell King - ARM Linux
>> <linux@arm•linux.org.uk> wrote:
>>> On Wed, Feb 17, 2016 at 08:52:36AM +0100, Marek Szyprowski wrote:
>>>> Then the only solution right now I see is to get back to v1:
>>>> http://lists.infradead.org/pipermail/linux-arm-kernel/2015-November/388199.html
>>>> which at least handles correctly device registration when power domain
>>>> driver is available.
>>> ... and which has the ability to break platforms if the PM domain is
>>> not already available.
>>>
>>> What's wrong with the patch in the link above _combined_ with a patch
>>> which addresses the concern I have with that patch: build a list of
>>> the failed-to-register devices, and retry them later - maybe from a
>>> late_initcall(), or a similar mechanism?
>> This will improve the robustness of the device registration process,
>> but I wonder if it's really worth the efforts of complicating the amba
>> device registration code.
>>
>> The problem I see with such approach, is to know *when* shall we retry
>> to register the devices.
>>
>> We will rely on the PM domain driver to be probed, as to have the
>> corresponding OF genpd provider registered, else the device
>> registration will continue to fail.
>> Now, I don't think there are PM domain drivers as removable modules
>> (yet), but in such cases a late_initcall won't help much.
>>
>>> My view is the risk to existing systems is _too_ high to apply either
>>> this patch, or the patch you link to above, and I refuse to play the
>>> "lets apply it and see if we break anything" lottery with this.
>> I agree!
>>
>> Although I think with some adjustments, perhaps we can move forward with v1?
>>
>> The adjustments I think is needed:
>> Instead of propagating the error code from dev_pm_domain_attach(),
>> let's print a debug message and continue the device registration.
>> In that way, we shouldn't introduce regressions for cases where the OF
>> genpd provider hasn't yet been registered, but the issue Marek is
>> trying to solve for Exynos should be fixed.
>>
>> What do you think?
>>
> Ping. Any news on this? Would be nice if we could agree on a way forward.
I'm sorry for the lack of any update for quite a long time, but I was
terribly
busy with some internal stuff. I will send v6 in a few minutes based on the
late_initcall idea from Russell.
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
next prev parent reply other threads:[~2016-04-12 14:09 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-10 10:47 [PATCH v5 RESEND 0/5] AMBA: add complete support for power domains Marek Szyprowski
2016-02-10 10:47 ` [PATCH v5 RESEND 1/5] drivers: nvdimm: ensure no negative value gets returned on positive match Marek Szyprowski
2016-02-10 10:47 ` [PATCH v5 RESEND 2/5] ARM: sa1111: " Marek Szyprowski
2016-02-10 16:39 ` Ulf Hansson
2016-02-10 10:47 ` [PATCH v5 RESEND 3/5] driver core: handle -EPROBE_DEFER from bus_type.match() Marek Szyprowski
2016-02-12 3:19 ` Greg Kroah-Hartman
2016-02-10 10:47 ` [PATCH v5 RESEND 4/5] ARM: amba: Move reading of periphid to amba_match() Marek Szyprowski
2016-02-15 17:52 ` Russell King - ARM Linux
2016-02-16 16:31 ` Russell King - ARM Linux
2016-02-17 7:52 ` Marek Szyprowski
2016-02-17 20:08 ` Russell King - ARM Linux
2016-03-02 10:16 ` Ulf Hansson
2016-04-12 11:39 ` Ulf Hansson
2016-04-12 14:09 ` Marek Szyprowski [this message]
2016-04-12 14:09 ` [PATCH v6] drivers: amba: properly handle devices with power domains Marek Szyprowski
2016-04-12 14:49 ` Ulf Hansson
2016-02-10 10:47 ` [PATCH v5 RESEND 5/5] ARM: amba: Properly " Marek Szyprowski
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