From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rob Herring Subject: Re: [RFC][PATCH] misc: Introduce reboot_reason driver Date: Thu, 10 Dec 2015 14:24:11 -0600 Message-ID: References: <1449610162-30543-1-git-send-email-john.stultz@linaro.org> <10759786.VG6jMebqAj@wuerfel> <1721197.gFcIQMjGvs@wuerfel> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: In-Reply-To: Sender: linux-arm-msm-owner@vger.kernel.org To: John Stultz Cc: Arnd Bergmann , Bjorn Andersson , lkml , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Vinay Simha BN , Haojian Zhuang , "devicetree@vger.kernel.org" , Android Kernel Team , Andy Gross , "linux-arm-msm@vger.kernel.org" List-Id: devicetree@vger.kernel.org On Thu, Dec 10, 2015 at 12:56 PM, John Stultz wrote: > On Thu, Dec 10, 2015 at 6:52 AM, Arnd Bergmann wrote: >> On Wednesday 09 December 2015 17:19:52 John Stultz wrote: >>> >>> If the concern is that since DT is basically ABI, one might not want >>> to have such a wide interface that specifies all the different >>> reasons, I can understand that. Though I'm really not sure how else we >>> would be able to specify the device supported the reboot reason logic >>> w/o having something in the DT (since some device may use the same soc >>> w/ the same reboot logic may use a different bootloader which doesn't >>> support the reason methods). At that point if we don't describe the >>> method clearly, it ends up being something closer to just a quirks >>> list which we'd have to map internally to behavior, which doesn't seem >>> great. >>> >>> Should we run into hardware that the proposed driver doesn't handle, >>> we can introduce a new driver for those specific semantics, but this >>> way we can share at least most of the logic, no? >> >> I think we need a layered approach, with some high-level code to >> store the boot reason, but then support firmware specific backends >> to that. If we just need a phandle for an SRAM partition and an offset >> within it, that can be done by the high-level driver, but not >> any of the more sophisticated communication methods. > > Hrm. This feels to me like over-design, though. We already have the > restart notifiers to hook into, which provide the command string. So > its just a matter of parsing the string and writing the appropriate > magic in the appropriate way (to memory, registers, efi, whatever). > The amount of code we'd be dealing with to have a front end and 3-4 > back-ends, vs having 3-4 separate drivers seems like it would almost > be the same. So why try to make a more complicated infrastructure? The fact that we are using notifiers for reset reason and triggering is probably some indication that some infrastructure is needed. But I don't think you need to do that here as long as it is all kernel internals. We'll make the 2nd guy do it. ;) Rob