From 5a258bd31dab2dad8afcced8a7a85fa92e04edab Mon Sep 17 00:00:00 2001 From: Neil Armstrong Date: Wed, 28 Feb 2018 16:07:18 +0100 Subject: [PATCH] drm/meson: Fixes for drm_crtc_vblank_on/off support Since Linux 4.17, calls to drm_crtc_vblank_on/off are mandatory, and we get a warning when ctrc is disabled : driver forgot to call drm_crtc_vblank_off() But, the vsync IRQ was not totally disabled due the transient hardware state, thus adding proper IRQ masking from the HHI system control registers. The last change fixes a race condition introduced by calling the added drm_crtc_vblank_on/off when an HPD event occurs from the HDMI connector, triggering a WARN_ON() in the _atomic_bebin() callback when the CRTC is disabled, thus also triggering a WARN_ON() in drm_vblank_put() : WARNING: CPU: 0 PID: 1185 at drivers/gpu/drm/meson/meson_crtc.c:157 meson_crtc_atomic_begin+0x78/0x80 [...] Call trace: meson_crtc_atomic_begin+0x78/0x80 drm_atomic_helper_commit_planes+0x140/0x218 drm_atomic_helper_commit_tail+0x38/0x80 commit_tail+0x7c/0x80 drm_atomic_helper_commit+0xdc/0x150 drm_atomic_commit+0x54/0x60 restore_fbdev_mode_atomic+0x198/0x238 restore_fbdev_mode+0x6c/0x1c0 drm_fb_helper_restore_fbdev_mode_unlocked+0x7c/0xf0 drm_fb_helper_set_par+0x34/0x60 drm_fb_helper_hotplug_event.part.28+0xb8/0xc8 drm_fbdev_client_hotplug+0xa4/0xe0 drm_client_dev_hotplug+0x90/0xe0 drm_kms_helper_hotplug_event+0x3c/0x48 drm_helper_hpd_irq_event+0x134/0x168 dw_hdmi_top_thread_irq+0x3c/0x50 [...] WARNING: CPU: 0 PID: 1185 at drivers/gpu/drm/drm_vblank.c:1026 drm_vblank_put+0xb4/0xc8 [...] Call trace: drm_vblank_put+0xb4/0xc8 drm_crtc_vblank_put+0x24/0x30 drm_atomic_helper_wait_for_vblanks.part.9+0x130/0x2b8 drm_atomic_helper_commit_tail+0x68/0x80 [...] The issue is the vblank need to be enabled in any occurence of : - atomic_enable() - atomic_begin() and state->enable == true, which was not the case Moving the CRTC enable code to a common function and calling in one of these occurence solves this race condition and makes sure vblank is enabled in each call to _atomic_begin() from the HPD event leading to drm_atomic_helper_commit_planes(). To Summarize : - Make sure that the CRTC code will calls the drm_crtc_vblank_on/off - *Really* mask the Vsync IRQ - Initialize and enable vblank at the first _atomic_begin()/_atomic_enable() Signed-off-by: Neil Armstrong --- drivers/gpu/drm/meson/meson_crtc.c | 25 +++++++++++++++++++++++-- 1 file changed, 23 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/meson/meson_crtc.c b/drivers/gpu/drm/meson/meson_crtc.c index 6099997..f8e260b 100644 --- a/drivers/gpu/drm/meson/meson_crtc.c +++ b/drivers/gpu/drm/meson/meson_crtc.c @@ -46,6 +46,7 @@ struct meson_crtc { struct drm_crtc base; struct drm_pending_vblank_event *event; struct meson_drm *priv; + bool enabled; }; #define to_meson_crtc(x) container_of(x, struct meson_crtc, base) @@ -81,8 +82,7 @@ static const struct drm_crtc_funcs meson_crtc_funcs = { }; -static void meson_crtc_atomic_enable(struct drm_crtc *crtc, - struct drm_crtc_state *old_state) +static void meson_crtc_enable(struct drm_crtc *crtc) { struct meson_crtc *meson_crtc = to_meson_crtc(crtc); struct drm_crtc_state *crtc_state = crtc->state; @@ -106,6 +106,22 @@ static void meson_crtc_atomic_enable(struct drm_crtc *crtc, writel_bits_relaxed(VPP_POSTBLEND_ENABLE, VPP_POSTBLEND_ENABLE, priv->io_base + _REG(VPP_MISC)); + drm_crtc_vblank_on(crtc); + + meson_crtc->enabled = true; +} + +static void meson_crtc_atomic_enable(struct drm_crtc *crtc, + struct drm_crtc_state *old_state) +{ + struct meson_crtc *meson_crtc = to_meson_crtc(crtc); + struct meson_drm *priv = meson_crtc->priv; + + DRM_DEBUG_DRIVER("\n"); + + if (!meson_crtc->enabled) + meson_crtc_enable(crtc); + priv->viu.osd1_enabled = true; drm_crtc_vblank_on(crtc); @@ -139,6 +155,8 @@ static void meson_crtc_atomic_disable(struct drm_crtc *crtc, crtc->state->event = NULL; } + + meson_crtc->enabled = false; } static void meson_crtc_atomic_begin(struct drm_crtc *crtc, @@ -147,6 +165,9 @@ static void meson_crtc_atomic_begin(struct drm_crtc *crtc, struct meson_crtc *meson_crtc = to_meson_crtc(crtc); unsigned long flags; + if (crtc->state->enable && !meson_crtc->enabled) + meson_crtc_enable(crtc); + if (crtc->state->event) { WARN_ON(drm_crtc_vblank_get(crtc) != 0);