Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756742Ab3H2SaP (ORCPT ); Thu, 29 Aug 2013 14:30:15 -0400 Received: from mail-vb0-f51.google.com ([209.85.212.51]:33865 "EHLO mail-vb0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756516Ab3H2SaN (ORCPT ); Thu, 29 Aug 2013 14:30:13 -0400 MIME-Version: 1.0 In-Reply-To: <20130829181412.GX30088@pengutronix.de> References: <1377784762-24045-1-git-send-email-fabio.estevam@freescale.com> <20130829181412.GX30088@pengutronix.de> Date: Thu, 29 Aug 2013 15:30:12 -0300 Message-ID: Subject: Re: [PATCH v2] imx-drm: Fix probe failure From: Fabio Estevam To: Sascha Hauer Cc: Fabio Estevam , Dave Airlie , daniel.vetter@ffwll.ch, Greg Kroah-Hartman , linux-kernel Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3041 Lines: 73 On Thu, Aug 29, 2013 at 3:14 PM, Sascha Hauer wrote: > On Thu, Aug 29, 2013 at 10:59:22AM -0300, Fabio Estevam wrote: >> Since commit b5dc0d10 (drm/imx: kill firstopen callback) the following probe >> failure is seen: >> >> [drm] Supports vblank timestamp caching Rev 1 (10.10.2010). >> [drm] No driver support for vblank timestamp query. >> [drm] Initialized imx-drm 1.0.0 20120507 on minor 0 >> imx-ldb ldb.10: adding encoder failed with -16 >> imx-ldb: probe of ldb.10 failed with error -16 >> imx-ipuv3 2400000.ipu: IPUv3H probed >> imx-ipuv3 2800000.ipu: IPUv3H probed >> imx-ipuv3-crtc imx-ipuv3-crtc.0: adding crtc failed with -16. >> imx-ipuv3-crtc: probe of imx-ipuv3-crtc.0 failed with error -16 >> imx-ipuv3-crtc imx-ipuv3-crtc.1: adding crtc failed with -16. >> imx-ipuv3-crtc: probe of imx-ipuv3-crtc.1 failed with error -16 >> imx-ipuv3-crtc imx-ipuv3-crtc.2: adding crtc failed with -16. >> imx-ipuv3-crtc: probe of imx-ipuv3-crtc.2 failed with error -16 >> imx-ipuv3-crtc imx-ipuv3-crtc.3: adding crtc failed with -16. >> imx-ipuv3-crtc: probe of imx-ipuv3-crtc.3 failed with error -16 >> >> The reason for the probe failure is that now 'imxdrm->references' is incremented >> early in imx_drm_driver_load(), so the following checks in imx_drm_add_crtc() >> and imx_drm_add_encoder(): >> >> if (imxdrm->references) { >> ret = -EBUSY; >> goto err_busy; >> } >> >> ,will always fail. >> >> Let the drm core handle the references instead of doing this manually in >> imx-drm. In imx-drm-core the open and close callbacks map to drm_open and >> drm_close, which handle the references via open_count. >> >> After this patch, lvds panel is functional on a mx6qsabrelite board. >> >> Signed-off-by: Fabio Estevam >> --- >> Changes since v1: >> - Improved commit log by providing an explanation to the probe failure >> - Cc'ed Dave/Daniel >> >> @@ -485,11 +480,6 @@ int imx_drm_add_crtc(struct drm_crtc *crtc, >> >> mutex_lock(&imxdrm->mutex); >> >> - if (imxdrm->references) { >> - ret = -EBUSY; >> - goto err_busy; >> - } > > As I told in v1: Simply removing the code is not an option. We agreed > that we use the drm core reference counting, so you must actually test > for it here... Yes, we did, but after reading a separate thread on this topic, I learned that drm core does not support it currently. Daniel mentions [1]: "And I wouldn't worry about module unloading and refcounting for now since core drm is terminally broken in that area already anyway" [1] http://www.mail-archive.com/dri-devel@lists.freedesktop.org/msg43698.html Can't we just apply this patch so that imx-drm can be functional again and fix module unloading/refcount later? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/