Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932440AbbKLQsJ (ORCPT ); Thu, 12 Nov 2015 11:48:09 -0500 Received: from foss.arm.com ([217.140.101.70]:37294 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932234AbbKLQsH (ORCPT ); Thu, 12 Nov 2015 11:48:07 -0500 Date: Thu, 12 Nov 2015 16:48:04 +0000 From: Liviu Dudau To: Thierry Reding Cc: Mark yao , DRI devel , lkml Subject: Re: drm: Bogus WARN() in drm_atomic_helper_update_legacy_modeset_state() ? Message-ID: <20151112164804.GD963@e106497-lin.cambridge.arm.com> References: <20151110150102.GP963@e106497-lin.cambridge.arm.com> <56444EA1.3050506@rock-chips.com> <20151112103618.GY963@e106497-lin.cambridge.arm.com> <56446EC2.6020301@rock-chips.com> <20151112133411.GA645@ulmo> <20151112140335.GC963@e106497-lin.cambridge.arm.com> <20151112161233.GA3913@ulmo> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20151112161233.GA3913@ulmo> 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: 9811 Lines: 210 On Thu, Nov 12, 2015 at 05:12:33PM +0100, Thierry Reding wrote: > On Thu, Nov 12, 2015 at 02:03:35PM +0000, Liviu Dudau wrote: > > On Thu, Nov 12, 2015 at 02:34:11PM +0100, Thierry Reding wrote: > > > On Thu, Nov 12, 2015 at 06:49:38PM +0800, Mark yao wrote: > > > > On 2015年11月12日 18:36, Liviu Dudau wrote: > > > > >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 > > > > Hi Liviu > > > > drivers/gpu/drm/i2c/tda998x_drv.c do the same things: > > > > priv->connector.encoder = &priv->encoder; > > > > drm_mode_connector_attach_encoder(&priv->connector, &priv->encoder); > > > > > > > > I believe must be same problem. > > > > > > Oh, I hadn't noticed this subthread, but you came to the same conclusion > > > as I did. I have the below local change, which I think might be good to > > > have given that there are at least two drivers that got this wrong. > > > > > > Thierry > > > > > > --- >8 --- > > > diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c > > > index 24c5434abd1c..56d53106b32d 100644 > > > --- a/drivers/gpu/drm/drm_crtc.c > > > +++ b/drivers/gpu/drm/drm_crtc.c > > > @@ -4983,6 +4983,20 @@ int drm_mode_connector_attach_encoder(struct drm_connector *connector, > > > { > > > int i; > > > > > > + /* > > > + * In the past, drivers have attempted to model the static association > > > + * of connector to encoder in simple connector/encoder devices using a > > > + * direct assignment of connector->encoder = encoder. This connection > > > + * is a logical one and the responsibility of the core, so drivers are > > > + * expected not to mess with this. > > > + * > > > + * Note that the error return should've been enough here, but a large > > > + * majority of drivers ignores the return value, so add in a big WARN > > > + * to get people's attention. > > > + */ > > > + if (WARN_ON(connector->encoder)) > > > + return -EINVAL; > > > + > > > for (i = 0; i < DRM_CONNECTOR_MAX_ENCODER; i++) { > > > if (connector->encoder_ids[i] == 0) { > > > connector->encoder_ids[i] = encoder->base.id; > > > > Hi Thierry, > > > > This patch together with your tda998x proposed patch should solve > > nicely the problem we are detecting, as long as no one calls > > drm_connector_get_encoder() before drm_crtc_helper_set_config(). > > The only caller of drm_connector_get_encoder() is drm_mode_getconnector() > and that handles the NULL case gracefully, so I don't think there are any > issues. Fine :) I'm happy to test any patch you might have and give you my Tested-by. Best regards, Liviu > > Thierry -- ==================== | 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/