From mboxrd@z Thu Jan 1 00:00:00 1970 From: m.szyprowski@samsung.com (Marek Szyprowski) Date: Thu, 26 Nov 2015 13:55:10 +0100 Subject: [PATCH 1/2] drivers: amba: properly handle devices with power domains In-Reply-To: References: <1448456127-31842-1-git-send-email-m.szyprowski@samsung.com> <1448456289-31960-1-git-send-email-m.szyprowski@samsung.com> <20151125132458.GL8644@n2100.arm.linux.org.uk> <5655B8F6.1070104@samsung.com> <20151125180953.GN8644@n2100.arm.linux.org.uk> <5656C527.8040804@samsung.com> Message-ID: <5657012E.1010702@samsung.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hello, On 2015-11-26 11:24, Ulf Hansson wrote: > On 26 November 2015 at 09:39, Marek Szyprowski wrote: >> On 2015-11-25 19:09, Russell King - ARM Linux wrote: >>> On Wed, Nov 25, 2015 at 02:56:10PM +0100, Ulf Hansson wrote: >>>> On 25 November 2015 at 14:34, Marek Szyprowski >>>> wrote: >>>>> Is ignoring dev_pm_domain_attach() return value a solution for you? >>>> That's probably better than nothing, but I wonder if it in practice >>>> will have any effect? >>> If the PM domain is down, then trying to tread the ID is likely to oops >>> the kernel. >> >> In my case kernel simply hangs (no single message, even when earlyprintk is >> enabled) >> instead of oopsing, that's why I've submitted this patch. >> > Okay. > > I suggest we go ahead and try that approach (ignoring the return > value). It's "quick fix", but the easiest way forward to solve the > problem. > > My only concern is if such change impacts the boot time. We should do > some tests to see if the change is negligible, if not we should > probably think of something else (like keeping the PM domain powered > until late_init). > > Russell, what do you think? Keeping PM domains powered until late_init would be a good idea regardless of the problem discussed here, because I often see that pm domains are turned on and off a dozen of times during typical boot of Exynos based systems. Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland