From mboxrd@z Thu Jan 1 00:00:00 1970 From: Inki Dae Subject: Re: [PATCH 1/1] ARM: exynos_defconfig: Disable IOMMU support Date: Fri, 06 Mar 2015 22:32:38 +0900 Message-ID: <54F9AC76.1000305@samsung.com> References: <1424173109-30347-1-git-send-email-javier.martinez@collabora.co.uk> <7hioehu8cn.fsf@linaro.org> <54F6C746.606@samsung.com> <54F6DD79.9070009@collabora.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mailout2.samsung.com ([203.254.224.25]:11944 "EHLO mailout2.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753449AbbCFNcl (ORCPT ); Fri, 6 Mar 2015 08:32:41 -0500 In-reply-to: <54F6DD79.9070009@collabora.co.uk> Sender: linux-samsung-soc-owner@vger.kernel.org List-Id: linux-samsung-soc@vger.kernel.org To: Javier Martinez Canillas Cc: Marek Szyprowski , Kevin Hilman , Kukjin Kim , Olof Johansson , Krzysztof Kozlowski , Andreas Faerber , linux-samsung-soc@vger.kernel.org, linux-kernel@vger.kernel.org, tyler.baker@linaro.org, Andrzej Hajda , Inki Dae , Gustavo Padovan Hi all, On 2015=EB=85=84 03=EC=9B=94 04=EC=9D=BC 19:24, Javier Martinez Canilla= s wrote: > +Gustavo which has been looking at the issues >=20 > Hello, >=20 > On 03/04/2015 09:50 AM, Marek Szyprowski wrote: >> Hello, >> >> On 2015-03-03 21:36, Kevin Hilman wrote: >>> Javier Martinez Canillas writes: >>> >>>> Enabling Exynos DRM IOMMU support for Exynos is currently broken a= nd >>>> causes a BUG on exynos-iommu driver. This was not an issue since t= he >>>> options was disabled in exynos_defconfig but after commit 8dcc14f8= 2f06 >>>> ("drm/exynos: IOMMU support should not be selectable by user"), it= is >>>> selected if EXYNOS_IOMMU is enabled which is in exynos_defconfig. >>>> >>>> So a kernel built using exynos_defconfig after the mentioned commi= t >>>> fails to boot [0]. Disable IOMMU support in Exynos defconfig until >>>> things get sorted out. >>> So some other exynos boards started failing in next-20150303[1], an= d >>> appear are DRM failures. >>> >>> Interestingly, (re)enabling CONFIG_EXYNOS_IOMMU for these cause thi= ngs to >>> work again. Even more intersting, with IOMMU enabled, peach-pi is >>> >=20 > I built both 4.0-rc2 and linux-next (tag next-20150303) with and with= out > CONFIG_EXYNOS_IOMMU and boot tested on Snow, Peach Pit and Pi. >=20 > We still don't have a Peach Pit hooked in LAVA so I tested it locally > and pasted the boot logs. >=20 > 4.0-rc2 (which has CONFIG_EXYNOS_IOMMU enabled) > ----------------------------------------------- >=20 > * Snow: NULL pointer dereference at fimd_wait_for_vblank [0] >=20 > * Peach Pi: kernel BUG at drivers/iommu/exynos-iommu.c:481 [1] >=20 > * Peach Pit: NULL pointer dereference at fimd_wait_for_vblank [2] >=20 > 4.0-rc2 + CONFIG_EXYNOS_IOMMU disabled > -------------------------------------- >=20 > * Snow: NULL pointer dereference at exynos_plane_destroy [3] >=20 > * Peach Pi: no error, kernel booted successfully [4] >=20 > * Peach Pit: NULL pointer dereference at exynos_plane_destroy [5] >=20 > next-20150303 (which has CONFIG_EXYNOS_IOMMU disabled) > ----------------------------------------------------- >=20 > * Snow: no error, kernel booted successfully [6] > * Peach Pi: no error, kernel booted successfully [7] > * Peach Pit: no error, kernel booted successfully [8] >=20 > next-20150303 + CONFIG_EXYNOS_IOMMU (re)enabled > ----------------------------------------------- >=20 > Snow: no error, kernel booted successfully [9] > Peach Pi: no error, kernel booted successfully [10] > Peach Pit: no error, kernel booted successfully [11] >=20 > Is interesting that the only Exynos5 machines that failed to boot in > next-20150303 were exynos5250-arndale and exynos5422-odroidxu3 [12]. >=20 > Also, only the exynos5250-arndale failed to boot with next-20150304 [= 13] > while exynos5422-odroidxu3 booted successfully and there were no chan= ges > for the exynos drm driver between next-20150303 and next-20150304. >=20 > Another interesting data point is that the error in next-20150303 for > these 2 boards was the NULL pointer dereference in exynos_plane_destr= oy > that I got with 4.0-rc2 (when IOMMU is disabled) in Snow and Peach Pi= t. I think the NULL pointer dereference issue may be fixed with below patc= h I merged to exynos-drm-fixes just a while ago, https://lkml.org/lkml/2015/2/17/434 Could you test it with this patch again? Thanks, Inki Dae >=20 > So it appears the error is not consistent and may be a race condition= =2E >=20 >>> I'm starting to think it's the DRM driver that needs to be disabled >>> until it actually gets some testing, rathre than disabling IOMMU. >> >=20 > It's true that there are a lot of issues with the Exynos DRM driver > but OTOH those are exposed because the config is enabled by default. >=20 > My fear is that if we disable the driver, it could silently break > and be noticed much later when a user enables the option. >=20 >> Well, this only shows that broken patch has been merged to exynos-dr= m-next >> kernel tree. I think that we should keep Exynos DRM enabled and give= Exynos >> DRM developers a chance to fix their stuff and then test their stuff= =2E >> >=20 > Agree, hopefully all these issues are sorted out during the -rc cycle= but > if not then I think we would have to disable the driver as Kevin sugg= ests. >=20 > Another thing that may be useful to detect these issues early is to h= ave > exynos-drm-next be pulled by linux-next since otherwise the integrati= on > is not tested until the changes are picked by the DRM maintainer. >=20 >> Best regards >> >=20 > Best regards, > Javier >=20 > [0]: https://lava.collabora.co.uk/scheduler/job/8559/log_file > [1]: https://lava.collabora.co.uk/scheduler/job/8558/log_file > [2]: http://hastebin.com/gupoworepa.xml > [3]: https://lava.collabora.co.uk/scheduler/job/8560/log_file > [4]: https://lava.collabora.co.uk/scheduler/job/8566/log_file > [5]: http://hastebin.com/ziyiruretu.xml > [6]: https://lava.collabora.co.uk/scheduler/job/8570/log_file > [7]: https://lava.collabora.co.uk/scheduler/job/8571/log_file > [8]: http://hastebin.com/felopehimi.vhdl > [9]: https://lava.collabora.co.uk/scheduler/job/8572/log_file > [10]: https://lava.collabora.co.uk/scheduler/job/8573/log_file > [11]: http://hastebin.com/kazupucufu.vhdl > [12]: http://kernelci.org/boot/?next-20150303&fail > [13]: http://kernelci.org/boot/?next-20150304&fail > -- > To unsubscribe from this list: send the line "unsubscribe linux-samsu= ng-soc" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >=20