From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Vetter Subject: Re: [PATCH 2/2] drm/atomic-helper: reset vblank on crtc reset Date: Fri, 29 May 2020 13:58:04 +0200 Message-ID: <20200529115804.GD1630358@phenom.ffwll.local> References: <20200527094757.1414174-1-daniel.vetter@ffwll.ch> <20200527094757.1414174-2-daniel.vetter@ffwll.ch> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20200527094757.1414174-2-daniel.vetter-/w4YWyX8dFk@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: DRI Development Cc: Intel Graphics Development , Daniel Vetter , Tetsuo Handa , syzbot+0871b14ca2e2fb64f6e3-Pl5Pbv+GP7P466ipTTIvnc23WoclnBCfAL8bYrjMMd8@public.gmane.org, "James (Qian) Wang" , Liviu Dudau , Mihail Atanassov , Brian Starkey , Sam Ravnborg , Boris Brezillon , Nicolas Ferre , Alexandre Belloni , Ludovic Desroches , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie List-Id: linux-tegra@vger.kernel.org On Wed, May 27, 2020 at 11:47:57AM +0200, Daniel Vetter wrote: > Only when vblanks are supported ofc. > > Some drivers do this already, but most unfortunately missed it. This > opens up bugs after driver load, before the crtc is enabled for the > first time. syzbot spotted this when loading vkms as a secondary > output. Given how many drivers are buggy it's best to solve this once > and for all in shared helper code. > > Aside from moving the few existing calls to drm_crtc_vblank_reset into > helpers (i915 doesn't use helpers, so keeps its own) I think the > regression risk is minimal: atomic helpers already rely on drivers > calling drm_crtc_vblank_on/off correctly in their hooks when they > support vblanks. And driver that's failing to handle vblanks after > this is missing those calls already, and vblanks could only work by > accident when enabling a CRTC for the first time right after boot. > > Big thanks to Tetsuo for helping track down what's going wrong here. > > There's only a few drivers which already had the necessary call and > needed some updating: > - komeda, atmel and tidss also needed to be changed to call > __drm_atomic_helper_crtc_reset() intead of open coding it > - tegra and msm even had it in the same place already, just code > motion, and malidp already uses __drm_atomic_helper_crtc_reset(). > > Only call left is in i915, which doesn't use drm_mode_config_reset, > but has its own fastboot infrastructure. So that's the only case where > we actually want this in the driver still. > > I've also reviewed all other drivers which set up vblank support with > drm_vblank_init. After the previous patch fixing mxsfb all atomic > drivers do call drm_crtc_vblank_on/off as they should, the remaining > drivers are either legacy kms or legacy dri1 drivers, so not affected > by this change to atomic helpers. Note that mxsfb has accidentally totally broken vblank support, so doesn't need fixing at all. I'll update that paragraph when merging. > > Link: https://syzkaller.appspot.com/bug?id=0ba17d70d062b2595e1f061231474800f076c7cb > Reported-by: Tetsuo Handa > Reported-by: syzbot+0871b14ca2e2fb64f6e3-Pl5Pbv+GP7P466ipTTIvnc23WoclnBCfAL8bYrjMMd8@public.gmane.org > Cc: Tetsuo Handa > Cc: "James (Qian) Wang" > Cc: Liviu Dudau > Cc: Mihail Atanassov > Cc: Brian Starkey > Cc: Sam Ravnborg > Cc: Boris Brezillon > Cc: Nicolas Ferre > Cc: Alexandre Belloni > Cc: Ludovic Desroches > Cc: Maarten Lankhorst > Cc: Maxime Ripard > Cc: Thomas Zimmermann > Cc: David Airlie > Cc: Daniel Vetter > Cc: Thierry Reding > Cc: Jonathan Hunter > Cc: Jyri Sarha > Cc: Tomi Valkeinen > Cc: Rob Clark > Cc: Sean Paul > Cc: Brian Masney > Cc: Emil Velikov > Cc: zhengbin > Cc: Thomas Gleixner > Cc: linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org > Signed-off-by: Daniel Vetter Ping for some more eyes and maybe testing on this patch here. Thanks, Daniel > --- > drivers/gpu/drm/arm/display/komeda/komeda_crtc.c | 7 ++----- > drivers/gpu/drm/arm/malidp_drv.c | 1 - > drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c | 7 ++----- > drivers/gpu/drm/drm_atomic_state_helper.c | 4 ++++ > drivers/gpu/drm/msm/disp/mdp5/mdp5_crtc.c | 2 -- > drivers/gpu/drm/tegra/dc.c | 1 - > drivers/gpu/drm/tidss/tidss_crtc.c | 3 +-- > drivers/gpu/drm/tidss/tidss_kms.c | 4 ---- > 8 files changed, 9 insertions(+), 20 deletions(-) > > diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c b/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c > index 56bd938961ee..f33418d6e1a0 100644 > --- a/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c > +++ b/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c > @@ -492,10 +492,8 @@ static void komeda_crtc_reset(struct drm_crtc *crtc) > crtc->state = NULL; > > state = kzalloc(sizeof(*state), GFP_KERNEL); > - if (state) { > - crtc->state = &state->base; > - crtc->state->crtc = crtc; > - } > + if (state) > + __drm_atomic_helper_crtc_reset(crtc, &state->base); > } > > static struct drm_crtc_state * > @@ -616,7 +614,6 @@ static int komeda_crtc_add(struct komeda_kms_dev *kms, > return err; > > drm_crtc_helper_add(crtc, &komeda_crtc_helper_funcs); > - drm_crtc_vblank_reset(crtc); > > crtc->port = kcrtc->master->of_output_port; > > diff --git a/drivers/gpu/drm/arm/malidp_drv.c b/drivers/gpu/drm/arm/malidp_drv.c > index c2507b7d8512..02904392e370 100644 > --- a/drivers/gpu/drm/arm/malidp_drv.c > +++ b/drivers/gpu/drm/arm/malidp_drv.c > @@ -870,7 +870,6 @@ static int malidp_bind(struct device *dev) > drm->irq_enabled = true; > > ret = drm_vblank_init(drm, drm->mode_config.num_crtc); > - drm_crtc_vblank_reset(&malidp->crtc); > if (ret < 0) { > DRM_ERROR("failed to initialise vblank\n"); > goto vblank_fail; > diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c > index 10985134ce0b..ce246b96330b 100644 > --- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c > +++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c > @@ -411,10 +411,8 @@ static void atmel_hlcdc_crtc_reset(struct drm_crtc *crtc) > } > > state = kzalloc(sizeof(*state), GFP_KERNEL); > - if (state) { > - crtc->state = &state->base; > - crtc->state->crtc = crtc; > - } > + if (state) > + __drm_atomic_helper_crtc_reset(crtc, &state->base); > } > > static struct drm_crtc_state * > @@ -528,7 +526,6 @@ int atmel_hlcdc_crtc_create(struct drm_device *dev) > } > > drm_crtc_helper_add(&crtc->base, &lcdc_crtc_helper_funcs); > - drm_crtc_vblank_reset(&crtc->base); > > drm_mode_crtc_set_gamma_size(&crtc->base, ATMEL_HLCDC_CLUT_SIZE); > drm_crtc_enable_color_mgmt(&crtc->base, 0, false, > diff --git a/drivers/gpu/drm/drm_atomic_state_helper.c b/drivers/gpu/drm/drm_atomic_state_helper.c > index 8fce6a115dfe..843964252239 100644 > --- a/drivers/gpu/drm/drm_atomic_state_helper.c > +++ b/drivers/gpu/drm/drm_atomic_state_helper.c > @@ -32,6 +32,7 @@ > #include > #include > #include > +#include > #include > > #include > @@ -93,6 +94,9 @@ __drm_atomic_helper_crtc_reset(struct drm_crtc *crtc, > if (crtc_state) > __drm_atomic_helper_crtc_state_reset(crtc_state, crtc); > > + if (crtc->dev->num_crtcs) > + drm_crtc_vblank_reset(crtc); > + > crtc->state = crtc_state; > } > EXPORT_SYMBOL(__drm_atomic_helper_crtc_reset); > diff --git a/drivers/gpu/drm/msm/disp/mdp5/mdp5_crtc.c b/drivers/gpu/drm/msm/disp/mdp5/mdp5_crtc.c > index ca3368c828d0..9606185c284b 100644 > --- a/drivers/gpu/drm/msm/disp/mdp5/mdp5_crtc.c > +++ b/drivers/gpu/drm/msm/disp/mdp5/mdp5_crtc.c > @@ -1117,8 +1117,6 @@ static void mdp5_crtc_reset(struct drm_crtc *crtc) > mdp5_crtc_destroy_state(crtc, crtc->state); > > __drm_atomic_helper_crtc_reset(crtc, &mdp5_cstate->base); > - > - drm_crtc_vblank_reset(crtc); > } > > static const struct drm_crtc_funcs mdp5_crtc_funcs = { > diff --git a/drivers/gpu/drm/tegra/dc.c b/drivers/gpu/drm/tegra/dc.c > index 83f31c6e891c..9b308b572eac 100644 > --- a/drivers/gpu/drm/tegra/dc.c > +++ b/drivers/gpu/drm/tegra/dc.c > @@ -1168,7 +1168,6 @@ static void tegra_crtc_reset(struct drm_crtc *crtc) > tegra_crtc_atomic_destroy_state(crtc, crtc->state); > > __drm_atomic_helper_crtc_reset(crtc, &state->base); > - drm_crtc_vblank_reset(crtc); > } > > static struct drm_crtc_state * > diff --git a/drivers/gpu/drm/tidss/tidss_crtc.c b/drivers/gpu/drm/tidss/tidss_crtc.c > index 89a226912de8..4d01c4af61cd 100644 > --- a/drivers/gpu/drm/tidss/tidss_crtc.c > +++ b/drivers/gpu/drm/tidss/tidss_crtc.c > @@ -352,8 +352,7 @@ static void tidss_crtc_reset(struct drm_crtc *crtc) > return; > } > > - crtc->state = &tcrtc->base; > - crtc->state->crtc = crtc; > + __drm_atomic_helper_crtc_reset(crtc, &tcrtc->base); > } > > static struct drm_crtc_state *tidss_crtc_duplicate_state(struct drm_crtc *crtc) > diff --git a/drivers/gpu/drm/tidss/tidss_kms.c b/drivers/gpu/drm/tidss/tidss_kms.c > index 4b99e9fa84a5..e6ab59eed259 100644 > --- a/drivers/gpu/drm/tidss/tidss_kms.c > +++ b/drivers/gpu/drm/tidss/tidss_kms.c > @@ -278,10 +278,6 @@ int tidss_modeset_init(struct tidss_device *tidss) > if (ret) > return ret; > > - /* Start with vertical blanking interrupt reporting disabled. */ > - for (i = 0; i < tidss->num_crtcs; ++i) > - drm_crtc_vblank_reset(tidss->crtcs[i]); > - > drm_mode_config_reset(ddev); > > dev_dbg(tidss->dev, "%s done\n", __func__); > -- > 2.26.2 > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch