From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marc Zyngier Subject: Re: [PATCH v14.1 01/17] drm: bridge: analogix/dp: split exynos dp driver to bridge directory Date: Wed, 8 Jun 2016 08:44:19 +0100 Message-ID: <20160608084419.602f02d2@arm.com> References: <1455534485-1154-1-git-send-email-ykk@rock-chips.com> <1455534576-1486-1-git-send-email-ykk@rock-chips.com> <1811552.qvsCm7GUs1@diego> <417ed48e-74e1-f747-34b9-0d1031a3d862@osg.samsung.com> <575774C0.4000900@rock-chips.com> Mime-Version: 1.0 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <575774C0.4000900-TNX95d0MmH7DzftRWevZcw@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Yakir Yang Cc: Javier Martinez Canillas , Heiko =?ISO-8859-1?Q?St=FCbner?= , Inki Dae , Andrzej Hajda , Joonyoung Shim , Seung-Woo Kim , Kyungmin Park , Jingoo Han , Thierry Reding , Krzysztof Kozlowski , Rob Herring , Mark Yao , Russell King , djkurtz-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org, Sean Paul , Kukjin Kim , Kumar Gala , emil.l.velikov-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, Ian Campbell , Gustavo Padovan , Kishon Vijay Abraham I , Pawel Moll , ajaynumb-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org List-Id: devicetree@vger.kernel.org On Wed, 8 Jun 2016 09:28:32 +0800 Yakir Yang wrote: > Hi Javier, >=20 > On 06/08/2016 01:06 AM, Javier Martinez Canillas wrote: > > Hello Yakir, > > > > On 03/17/2016 05:47 PM, Heiko St=FCbner wrote: =20 > >> Split the dp core driver from exynos directory to bridge directory= , > >> and rename the core driver to analogix_dp_*, rename the platform > >> code to exynos_dp. > >> > >> Beside the new analogix_dp driver would export six hooks. > >> "analogix_dp_bind()" and "analogix_dp_unbind()" > >> "analogix_dp_suspned()" and "analogix_dp_resume()" > >> "analogix_dp_detect()" and "analogix_dp_get_modes()" > >> > >> The bind/unbind symbols is used for analogix platform driver to co= nnect > >> with analogix_dp core driver. And the detect/get_modes is used for= analogix > >> platform driver to init the connector. > >> > >> They reason why connector need register in helper driver is rockch= ip drm > >> haven't implement the atomic API, but Exynos drm have implement it= , so > >> there would need two different connector helper functions, that's = why we > >> leave the connector register in helper driver. > >> > >> Signed-off-by: Yakir Yang > >> --- =20 > > Marc reported that his Exynos5250 Snow Chromebook fails to boot wit= h v4.7-rc. > > > > I've done a git bisect and tracked down to this commit. The problem= is a NULL > > pointer dereference to connector->dev in drm_mode_create(connector-= >dev) when > > called from exynos_dp_get_modes(). The error log is at [1]. > > > > I'm trying to figure out the issue but wanted to mention in case yo= u have any > > hints about what could be the cause. AFAICT the problem is related = to the fact > > that drm_connector_init() is called in analogix_dp_bridge_attach() = and the > > connector passed as argument is the one in struct analogix_dp_devic= e *dp, but > > later exynos_dp_get_modes() calls drm_mode_create() passing the con= nector in > > struct exynos_dp_device *dp, which has not been previously initiali= zed. =20 >=20 > Agree, this should be the problem, exynos_dp->connector haven't been > initialized, driver should make exynos_dp->dp to a connector point, a= nd > record the passing connector in exynos_dp_bridge_attach(), that shoul= d > fix this problem. >=20 >=20 > Thanks, > - Yakir >=20 >=20 > diff --git a/drivers/gpu/drm/exynos/exynos_dp.c=20 > b/drivers/gpu/drm/exynos/exynos_dp.c > index 468498e..4c1fb3f 100644 > --- a/drivers/gpu/drm/exynos/exynos_dp.c > +++ b/drivers/gpu/drm/exynos/exynos_dp.c > @@ -34,7 +34,7 @@ >=20 > struct exynos_dp_device { > struct drm_encoder encoder; > - struct drm_connector connector; > + struct drm_connector *connector; > struct drm_bridge *ptn_bridge; > struct drm_device *drm_dev; > struct device *dev; > @@ -70,7 +70,7 @@ static int exynos_dp_poweroff(struct=20 > analogix_dp_plat_data *plat_data) > static int exynos_dp_get_modes(struct analogix_dp_plat_data *plat_d= ata) > { > struct exynos_dp_device *dp =3D to_dp(plat_data); > - struct drm_connector *connector =3D &dp->connector; > + struct drm_connector *connector =3D dp->connector; > struct drm_display_mode *mode; > int num_modes =3D 0; >=20 > @@ -103,6 +103,7 @@ static int exynos_dp_bridge_attach(struct=20 > analogix_dp_plat_data *plat_data, > int ret; >=20 > drm_connector_register(connector); > + dp->connector =3D connector; >=20 > /* Pre-empt DP connector creation if there's a bridge */ > if (dp->ptn_bridge) { >=20 I've just tested this change, and in combination with Javier's DT patch= , my Snow is back to its useful state (I'm writing this email from that very Chromebook). Once you make this a proper patch, please add my: Tested-by: Marc Zyngier to it. Thanks a lot to you and Javier for tracking this down! M. --=20 Jazz is not dead. It just smells funny. -- To unsubscribe from this list: send the line "unsubscribe devicetree" i= n the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html