Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754156AbbKLKgX (ORCPT ); Thu, 12 Nov 2015 05:36:23 -0500 Received: from foss.arm.com ([217.140.101.70]:35384 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753602AbbKLKgV (ORCPT ); Thu, 12 Nov 2015 05:36:21 -0500 Date: Thu, 12 Nov 2015 10:36:19 +0000 From: Liviu Dudau To: Mark yao Cc: Daniel Vetter , David Airlie , Rob Clark , DRI devel , lkml Subject: Re: drm: Bogus WARN() in drm_atomic_helper_update_legacy_modeset_state() ? Message-ID: <20151112103618.GY963@e106497-lin.cambridge.arm.com> References: <20151110150102.GP963@e106497-lin.cambridge.arm.com> <56444EA1.3050506@rock-chips.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <56444EA1.3050506@rock-chips.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6199 Lines: 146 On Thu, Nov 12, 2015 at 04:32:33PM +0800, Mark yao wrote: > On 2015年11月10日 23:01, Liviu Dudau wrote: > > Hello, > > When booting my Juno board with the HDLCD driver that I have converted to > atomic operations I'm getting the following warning: > > ------------[ cut here ]------------ > WARNING: at /work/repositories/kernel/drivers/gpu/drm/drm_atomic_helper.c:674 > Modules linked in: hdlcd(+) clk_scpi > > CPU: 3 PID: 1375 Comm: systemd-udevd Not tainted 4.3.0-next-20151109+ #5 > Hardware name: ARM Juno development board (r0) (DT) > task: ffffffc974888b00 ti: ffffffc9755dc000 task.ti: ffffffc9755dc000 > PC is at drm_atomic_helper_update_legacy_modeset_state+0x204/0x20c > LR is at drm_atomic_helper_commit_modeset_disables+0x1c0/0x394 > pc : [] lr : [] pstate: 20000145 > sp : ffffffc9755df430 > x29: ffffffc9755df430 x28: ffffffc975703600 > x27: 0000000000000000 x26: ffffffc976253960 > x25: ffffffc976254040 x24: ffffffc000819000 > x23: ffffffc000689ea0 x22: ffffffc976251800 > x21: ffffffc976251800 x20: 0000000000000000 > x19: ffffffc9766b1f80 x18: 00000000715fe015 > x17: 0000007fb4b855b0 x16: 0000000000000220 > x15: 0000000000000001 x14: 0ffffffffffffffe > x13: 0000000000000008 x12: 0101010101010101 > x11: ffffffc000964000 x10: ffffffc0009d2000 > x9 : 0000000000000000 x8 : ffffffc97ff5f700 > x7 : ffffffc97566cb80 x6 : ffffffc9766b1700 > x5 : ffffffc975665100 x4 : 0000000000000000 > x3 : ffffffc976253960 x2 : ffffffc97566cd00 > x1 : ffffffc976253900 x0 : 0000000000000000 > > ---[ end trace 9fe289f798e7178e ]--- > Call trace: > [] drm_atomic_helper_update_legacy_modeset_state+0x204/0x20c > [] drm_atomic_helper_commit_modeset_disables+0x1c0/0x394 > [] drm_atomic_helper_commit+0xe0/0x150 > [] drm_atomic_commit+0x40/0x6c > [] restore_fbdev_mode+0x294/0x2d4 > [] drm_fb_helper_restore_fbdev_mode_unlocked+0x34/0x8c > [] drm_fb_helper_set_par+0x2c/0x58 > [] fbcon_init+0x4d4/0x534 > [] visual_init+0xac/0x104 > [] do_bind_con_driver+0x16c/0x398 > [] do_take_over_console+0xd8/0x1f4 > [] do_fbcon_takeover+0x74/0xf8 > [] fbcon_event_notify+0x8a4/0x8f8 > [] notifier_call_chain+0x4c/0x88 > [] __blocking_notifier_call_chain+0x44/0x74 > [] blocking_notifier_call_chain+0x14/0x1c > [] fb_notifier_call_chain+0x1c/0x24 > [] register_framebuffer+0x1c0/0x2ac > [] drm_fb_helper_initial_config+0x25c/0x3ec > [] drm_fbdev_cma_init+0x98/0x134 > [] hdlcd_drm_bind+0x180/0x498 [hdlcd] > [] try_to_bring_up_master.part.5+0xd4/0x118 > [] component_master_add_with_match+0xc4/0x148 > [] component_master_add+0x10/0x18 > [] hdlcd_probe+0x14/0x28 [hdlcd] > [] platform_drv_probe+0x54/0xc0 > [] driver_probe_device+0x1ec/0x2e8 > [] __driver_attach+0x9c/0xa0 > [] bus_for_each_dev+0x58/0x98 > [] driver_attach+0x20/0x28 > [] bus_add_driver+0x1c8/0x22c > [] driver_register+0x68/0x108 > [] __platform_driver_register+0x4c/0x54 > [] hdlcd_init+0x18/0x30 [hdlcd] > [] do_one_initcall+0x90/0x1a8 > [] do_init_module+0x60/0x1c8 > [] load_module+0x1554/0x1c98 > [] SyS_finit_module+0x7c/0x88 > [] el0_svc_naked+0x24/0x28 > > > The line that triggers the warning is: > > 674: WARN_ON(!connector->encoder->crtc); > > As far as I can see the encoder->crtc value is being set to a non-NULL value only > in two places: > - in drm_atomic_helper_update_legacy_modeset_state() after WARN_ON() > encoder->crtc = connector->state->crtc; > - in drm_crtc_helper_set_config(drm_mode_set *set): > encoder->crtc = new_crtc; > > Nothing in the call path from drm_atomic_commit() calls crtc_funcs->set_config() or > drm_crtc_helper_set_config() directly, so the question is if this WARN() is actually > valid. > > Call path from drm_atomic_commit: > > drm_atomic_helper_commit() > - drm_atomic_helper_prepare_planes() > - drm_atomic_helper_swap_state() > - drm_atomic_helper_commit_modeset_disables() > - disable_outputs() > - drm_atomic_helper_update_legacy_modeset_state() > - WARN_ON(!connector->encoder->crtc) > > Best regards, > Liviu > > > Hi Liviu > I solved this problem by following change, you can check if your driver do the same things: > drivers/gpu/drm/bridge/dw_hdmi.c: > - hdmi->connector.encoder = encoder; > +// hdmi->connector.encoder = encoder; > > drm_mode_connector_attach_encoder(&hdmi->connector, encoder); > > I found some other drivers set connector.encoder before drm_mode_connector_attach_encoder, some are not. > > drm_mode_connector_attach_encoder already describe the link of connector and encoder, > so I think "connector.encoder = encoder" is not needed, is that right? I'll have a look, thanks for pointing this. However, my setup uses the tda998x driver for encoder, so I will have to go look there rather than in my driver. Best regards, Liviu > > Thanks. > > -- > Ｍark Yao -- ==================== | I would like to | | fix the world, | | but they're not | | giving me the | \ source code! / --------------- ¯\_(ツ)_/¯ -- 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/