Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754032AbbKLNeR (ORCPT ); Thu, 12 Nov 2015 08:34:17 -0500 Received: from mail-wm0-f54.google.com ([74.125.82.54]:33299 "EHLO mail-wm0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753891AbbKLNeO (ORCPT ); Thu, 12 Nov 2015 08:34:14 -0500 Date: Thu, 12 Nov 2015 14:34:11 +0100 From: Thierry Reding To: Mark yao Cc: Liviu Dudau , DRI devel , lkml Subject: Re: drm: Bogus WARN() in drm_atomic_helper_update_legacy_modeset_state() ? Message-ID: <20151112133411.GA645@ulmo> 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> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="SLDf9lqlvOQaIe6s" Content-Disposition: inline In-Reply-To: <56446EC2.6020301@rock-chips.com> User-Agent: Mutt/1.5.23+102 (2ca89bed6448) (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 9080 Lines: 220 --SLDf9lqlvOQaIe6s Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Nov 12, 2015 at 06:49:38PM +0800, Mark yao wrote: > On 2015=E5=B9=B411=E6=9C=8812=E6=97=A5 18:36, Liviu Dudau wrote: > >On Thu, Nov 12, 2015 at 04:32:33PM +0800, Mark yao wrote: > >> On 2015=E5=B9=B411=E6=9C=8810=E6=97=A5 23:01, Liviu Dudau wrote: > >> > >> Hello, > >> > >> When booting my Juno board with the HDLCD driver that I have converte= d to > >> atomic operations I'm getting the following warning: > >> > >> ------------[ cut here ]------------ > >> WARNING: at /work/repositories/kernel/drivers/gpu/drm/drm_atomic_help= er.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+0x= 204/0x20c > >> [] 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+0x34/0= x8c > >> [] 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-NUL= L value only > >> in two places: > >> - in drm_atomic_helper_update_legacy_modeset_state() after WARN_ON() > >> encoder->crtc =3D connector->state->crtc; > >> - in drm_crtc_helper_set_config(drm_mode_set *set): > >> encoder->crtc =3D new_crtc; > >> > >> Nothing in the call path from drm_atomic_commit() calls crtc_funcs->s= et_config() or > >> drm_crtc_helper_set_config() directly, so the question is if this WAR= N() 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 y= our driver do the same things: > >> drivers/gpu/drm/bridge/dw_hdmi.c: > >> - hdmi->connector.encoder =3D encoder; > >> +// hdmi->connector.encoder =3D encoder; > >> > >> drm_mode_connector_attach_encoder(&hdmi->connect= or, encoder); > >> > >> I found some other drivers set connector.encoder before drm_mo= de_connector_attach_encoder, some are not. > >> > >> drm_mode_connector_attach_encoder already describe the link of= connector and encoder, > >> so I think "connector.encoder =3D encoder" is not needed, is that r= ight? > >I'll have a look, thanks for pointing this. However, my setup uses the t= da998x driver for encoder, so I will > >have to go look there rather than in my driver. > > > >Best regards, > >Liviu > > > >> Thanks. > >> > >> -- > >> =EF=BC=ADark Yao > Hi Liviu > drivers/gpu/drm/i2c/tda998x_drv.c do the same things: > priv->connector.encoder =3D &priv->encoder; > drm_mode_connector_attach_encoder(&priv->connector, &priv->encoder); >=20 > 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_con= nector *connector, { int i; =20 + /* + * 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 =3D 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 =3D 0; i < DRM_CONNECTOR_MAX_ENCODER; i++) { if (connector->encoder_ids[i] =3D=3D 0) { connector->encoder_ids[i] =3D encoder->base.id; --SLDf9lqlvOQaIe6s Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAABCAAGBQJWRJVTAAoJEN0jrNd/PrOhIP0P/1bnlMDBDqON4QzRKSNGC0W4 mB7XRYW4WRKbQlnRNfAQXWySH1CTxVsIXUxqJNn+hY2ybC3Yoz2DFcNXu3HMNpYh QJhlluLmI4v3QuEy/BB5E+9E6NPvk2d5/+F7ZGPlSKz4g14/1sBVLRQZAoL7O66L eiCmXAZ7nxmzoM1T8tDjVVp/ydQxQKRLiPs2vEs00UEDuNYaJyejcITpMd6BdzSt Q0CpH8+4YWxCjmtXi0piTol6StuDiEGJnLOh4/Pa3pNpejsUTWGVfkrMxlpL9mai m4a6vD62YAJJNblquDCqRz8llHCVfK3er2KtT8bQRcRilqyrcZxf8b/N31t1Z8MA jLDw0EBGVYAjWAJPYyOcGHem/fDVV/TWcdI05ftOJ8596ZobJG3VkJaHwSlwssx7 hF4YU2XH32J13rHmmyJsE2VapBh9N117tZIxc/JGywGbDhv57eCdEuHIsawo5LBc vndLpb8iqhVnit7TL9Kj28SDSlO+iJwyxHMcZ214StWBbs60VbMEdUx1Xi5mahy4 UCTNcrOgnDxUz/hPHYtT7np4fC6F3O5bF57ktv1AHlJ9rF/nbbIw5GUThhzVqj8X zLWexAehiPhqtlZ3hqe3H73TGTGFYgLcXzG5pGua9CxVAhVIvvzrAehBGbTvpdbX iqMlRtex45UPkz02inTR =z2kM -----END PGP SIGNATURE----- --SLDf9lqlvOQaIe6s-- -- 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/