From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marek Szyprowski Subject: Re: [PATCH v5 RESEND 4/5] ARM: amba: Move reading of periphid to amba_match() Date: Tue, 12 Apr 2016 16:09:02 +0200 Message-ID: <570D017E.7060105@samsung.com> References: <1455101250-11327-1-git-send-email-m.szyprowski@samsung.com> <1455101250-11327-5-git-send-email-m.szyprowski@samsung.com> <20160215175250.GJ10826@n2100.arm.linux.org.uk> <56C426C4.7040907@samsung.com> <20160217200828.GH19428@n2100.arm.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mailout1.w1.samsung.com ([210.118.77.11]:51211 "EHLO mailout1.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933536AbcDLOJH (ORCPT ); Tue, 12 Apr 2016 10:09:07 -0400 Received: from eucpsbgm1.samsung.com (unknown [203.254.199.244]) by mailout1.w1.samsung.com (Oracle Communications Messaging Server 7.0.5.31.0 64bit (built May 5 2014)) with ESMTP id <0O5I00HKFXZ34QA0@mailout1.w1.samsung.com> for linux-samsung-soc@vger.kernel.org; Tue, 12 Apr 2016 15:09:03 +0100 (BST) In-reply-to: Sender: linux-samsung-soc-owner@vger.kernel.org List-Id: linux-samsung-soc@vger.kernel.org To: Ulf Hansson , Russell King - ARM Linux Cc: linux-samsung-soc , "linux-arm-kernel@lists.infradead.org" , Kukjin Kim , Krzysztof Kozlowski , Bartlomiej Zolnierkiewicz Hi Ulf, On 2016-04-12 13:39, Ulf Hansson wrote: > - trimmed cc list > > On 2 March 2016 at 11:16, Ulf Hansson wrote: >> On 17 February 2016 at 21:08, Russell King - ARM Linux >> 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 From mboxrd@z Thu Jan 1 00:00:00 1970 From: m.szyprowski@samsung.com (Marek Szyprowski) Date: Tue, 12 Apr 2016 16:09:02 +0200 Subject: [PATCH v5 RESEND 4/5] ARM: amba: Move reading of periphid to amba_match() In-Reply-To: References: <1455101250-11327-1-git-send-email-m.szyprowski@samsung.com> <1455101250-11327-5-git-send-email-m.szyprowski@samsung.com> <20160215175250.GJ10826@n2100.arm.linux.org.uk> <56C426C4.7040907@samsung.com> <20160217200828.GH19428@n2100.arm.linux.org.uk> Message-ID: <570D017E.7060105@samsung.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Ulf, On 2016-04-12 13:39, Ulf Hansson wrote: > - trimmed cc list > > On 2 March 2016 at 11:16, Ulf Hansson wrote: >> On 17 February 2016 at 21:08, Russell King - ARM Linux >> 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