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From 5a258bd31dab2dad8afcced8a7a85fa92e04edab Mon Sep 17 00:00:00 2001
From: Neil Armstrong <narmstrong@baylibre.com>
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 <narmstrong@baylibre.com>
---
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);
|
