From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrzej Hajda Subject: Re: drm/exynos: fimd: vrefresh is zero Date: Thu, 05 May 2016 11:22:41 +0200 Message-ID: <572B10E1.4060704@samsung.com> References: <5725259C.9020206@math.uni-bielefeld.de> <5727648D.7050603@math.uni-bielefeld.de> <20160502202257.GW14148@phenom.ffwll.local> <5727B8E6.6050106@math.uni-bielefeld.de> <572B0E7C.6010408@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: Received: from mailout4.w1.samsung.com ([210.118.77.14]:45044 "EHLO mailout4.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756429AbcEEJW5 (ORCPT ); Thu, 5 May 2016 05:22:57 -0400 Received: from eucpsbgm2.samsung.com (unknown [203.254.199.245]) by mailout4.w1.samsung.com (Oracle Communications Messaging Server 7.0.5.31.0 64bit (built May 5 2014)) with ESMTP id <0O6P00N8D6263820@mailout4.w1.samsung.com> for linux-samsung-soc@vger.kernel.org; Thu, 05 May 2016 10:22:54 +0100 (BST) In-reply-to: <572B0E7C.6010408@samsung.com> Sender: linux-samsung-soc-owner@vger.kernel.org List-Id: linux-samsung-soc@vger.kernel.org To: Daniel Vetter , Tobias Jakobi Cc: linux-samsung-soc , Maling list - DRI developers On 05/05/2016 11:12 AM, Andrzej Hajda wrote: > > Regarding the initial question, mode->vrefresh is set in > drm_helper_probe_single_connector_modes. I guess division by zero could > be caused by lack of clock in timings provided by dts timing node. > As I remember in the past dts timings were passed without provided > clock, in such case driver calculated mode->clock for some default value > of vrefresh (60Hz for fimd if I remember correctly). Later validation > code was added and the clock should be always provided. > DTS files were updated after some time and the recalculation code was > removed from fimd driver. So it is possible you are a victim of this change. One more thing, I have looked at Exynos DTS files in mainline. In case of exynos5*.dts files clock-frequency is set to 50000, it is of course insanely low value and vrefresh calculated for such timings will be 0. So please verify if clock-frequency is not too low in your case. Regards Andrzej > > Regarding usage by drivers, from a quick look it seems to be used for > something more than debugging by: > - amdgpu, > - exynos, > - adv7511, > - intel_dp(?), > - mdp5_cmd_encoder(?), > - nouveau, > - omap(?), > - tilcdc. > > Regards > Andrzej > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel >