From mboxrd@z Thu Jan 1 00:00:00 1970 From: Javier Martinez Canillas Subject: Re: [PATCH v14.1 01/17] drm: bridge: analogix/dp: split exynos dp driver to bridge directory Date: Wed, 8 Jun 2016 10:19:04 -0400 Message-ID: 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> <20160608084419.602f02d2@arm.com> <5757F917.2030506@rock-chips.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <5757F917.2030506@rock-chips.com> Sender: linux-samsung-soc-owner@vger.kernel.org To: Yakir Yang , Marc Zyngier Cc: =?UTF-8?Q?Heiko_St=c3=bcbner?= , Inki Dae , Andrzej Hajda , Joonyoung Shim , Seung-Woo Kim , Kyungmin Park , Jingoo Han , Thierry Reding , Krzysztof Kozlowski , Rob Herring , Mark Yao , Russell King , djkurtz@chromium.org, Sean Paul , Kukjin Kim , Kumar Gala , emil.l.velikov@gmail.com, Ian Campbell , Gustavo Padovan , Kishon Vijay Abraham I , Pawel Moll , ajaynumb@gmail.com, robherring2@gmail.com, Andy Yan , dri-d List-Id: devicetree@vger.kernel.org On 06/08/2016 06:53 AM, Yakir Yang wrote: > Marc, Javier >=20 > On 06/08/2016 03:44 PM, Marc Zyngier wrote: >> On Wed, 8 Jun 2016 09:28:32 +0800 >> Yakir Yang wrote: >> >>> Hi Javier, >>> >>> On 06/08/2016 01:06 AM, Javier Martinez Canillas wrote: >>>> Hello Yakir, >>>> >>>> On 03/17/2016 05:47 PM, Heiko St=FCbner wrote: >>>>> Split the dp core driver from exynos directory to bridge director= y, >>>>> 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 c= onnect >>>>> with analogix_dp core driver. And the detect/get_modes is used fo= r analogix >>>>> platform driver to init the connector. >>>>> >>>>> They reason why connector need register in helper driver is rockc= hip drm >>>>> haven't implement the atomic API, but Exynos drm have implement i= t, 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 >>>>> --- >>>> Marc reported that his Exynos5250 Snow Chromebook fails to boot wi= th v4.7-rc. >>>> >>>> I've done a git bisect and tracked down to this commit. The proble= m 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 y= ou 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_devi= ce *dp, but >>>> later exynos_dp_get_modes() calls drm_mode_create() passing the co= nnector in >>>> struct exynos_dp_device *dp, which has not been previously initial= ized. >>> Agree, this should be the problem, exynos_dp->connector haven't bee= n >>> initialized, driver should make exynos_dp->dp to a connector point,= and >>> record the passing connector in exynos_dp_bridge_attach(), that sho= uld >>> fix this problem. >>> >>> >>> Thanks, >>> - Yakir >>> >>> >>> diff --git a/drivers/gpu/drm/exynos/exynos_dp.c >>> 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 @@ >>> >>> 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 >>> analogix_dp_plat_data *plat_data) >>> static int exynos_dp_get_modes(struct analogix_dp_plat_data *pla= t_data) >>> { >>> 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; >>> >>> @@ -103,6 +103,7 @@ static int exynos_dp_bridge_attach(struct >>> analogix_dp_plat_data *plat_data, >>> int ret; >>> >>> drm_connector_register(connector); >>> + dp->connector =3D connector; >>> >>> /* Pre-empt DP connector creation if there's a bridge */ >>> if (dp->ptn_bridge) { >>> >> I've just tested this change, and in combination with Javier's DT pa= tch, >> my Snow is back to its useful state (I'm writing this email from tha= t >> very Chromebook). >> Great. I also tested and the Snow booted but I don't have physical acce= ss to check if the display was brought correctly, So thanks a lot for test= ing. >> Once you make this a proper patch, please add my: >> >> Tested-by: Marc Zyngier >=20 > I guess Javier should be the best one to create this patch, if he hav= e no time, i would do it for him. thanks for your report ;) > Done. > - Yakir >=20 >> to it. >> >> Thanks a lot to you and Javier for tracking this down! >> Thanks to you for reporting all the issues! Best regards, --=20 Javier Martinez Canillas Open Source Group Samsung Research America