From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrzej Hajda Subject: Re: [PATCH] drm/exynos: resolve infinite loop issue on non multi-platform Date: Fri, 07 Nov 2014 09:29:54 +0100 Message-ID: <545C8302.30701@samsung.com> References: <1415283007-10096-1-git-send-email-inki.dae@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: Received: from mailout3.w1.samsung.com ([210.118.77.13]:53560 "EHLO mailout3.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751020AbaKGIaA (ORCPT ); Fri, 7 Nov 2014 03:30:00 -0500 Received: from eucpsbgm2.samsung.com (unknown [203.254.199.245]) by mailout3.w1.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0NEN0049UUEQJ670@mailout3.w1.samsung.com> for linux-samsung-soc@vger.kernel.org; Fri, 07 Nov 2014 08:32:50 +0000 (GMT) In-reply-to: <1415283007-10096-1-git-send-email-inki.dae@samsung.com> Sender: linux-samsung-soc-owner@vger.kernel.org List-Id: linux-samsung-soc@vger.kernel.org To: Inki Dae , airlied@linux.ie, dri-devel@lists.freedesktop.org Cc: linux-samsung-soc@vger.kernel.org On 11/06/2014 03:10 PM, Inki Dae wrote: > This patch resovles the infinite loop issue incurred > when Exyno drm driver is enabled but all kms drivers > are disabled on Exynos board by returning -EPROBE_DEFER > only in case that there is kms device registered. There are many different cases it can still fail: - there are no matching device nodes in DT, - some devices are present in DT, some drivers are enabled, but they do not match, - even if there exists some pairs device_node-driver it can fail - exynos_drm_match_add requires higher level matches - every crtc should have matching encoder. I think even super-node will not solve all these issues. The real problem here is that during probe of exynos_drm ipp driver is successfully probed and after that exynos_drm probe fails, which causes also removing ipp, anyway successful ipp probe triggers whole re-probe mechanism again. It creates infinite loop. I think moving exynos_platform_device_ipp_register after component_master_add_with_match should solve some of the issue, but I guess it could create new ones, or maybe not, needs checking. On the other side I wonder if we really need to have ipp device at all, replacing it with helpers of exynos_drm should be possible, I guess. Regards Andrzej > > Signed-off-by: Inki Dae > --- > drivers/gpu/drm/exynos/exynos_drm_drv.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/drivers/gpu/drm/exynos/exynos_drm_drv.c b/drivers/gpu/drm/exynos/exynos_drm_drv.c > index ecc86aa..14c6af7 100644 > --- a/drivers/gpu/drm/exynos/exynos_drm_drv.c > +++ b/drivers/gpu/drm/exynos/exynos_drm_drv.c > @@ -488,6 +488,12 @@ static struct component_match *exynos_drm_match_add(struct device *dev) > > mutex_lock(&drm_component_lock); > > + /* Do not retry to probe if there is no any kms driver regitered. */ > + if (list_empty(&drm_component_list)) { > + mutex_unlock(&drm_component_lock); > + return ERR_PTR(-ENODEV); > + } > + > list_for_each_entry(cdev, &drm_component_list, list) { > /* > * Add components to master only in case that crtc and >