[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Sat, 08 Aug 2015 17:04:11 +0100
From: Russell King <rmk+kernel@....linux.org.uk>
To: linux-rockchip@...ts.infradead.org,
dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org
Cc: Philipp Zabel <p.zabel@...gutronix.de>,
Andy Yan <andy.yan@...k-chips.com>,
Yakir Yang <ykk@...k-chips.com>,
Fabio Estevam <fabio.estevam@...escale.com>,
Sascha Hauer <s.hauer@...gutronix.de>,
Jon Nettleton <jon.nettleton@...il.com>,
David Airlie <airlied@...ux.ie>
Subject: [PATCH 10/12] drm: bridge/dw_hdmi: fix phy enable/disable handling
The dw_hdmi enable/disable handling is particularly weak in several
regards:
* The hotplug interrupt could call hdmi_poweron() or hdmi_poweroff()
while DRM is setting a mode, which could race with a mode being set.
* Hotplug will always re-enable the phy whenever it detects an active
hotplug signal, even if DRM has disabled the output.
Resolve all of these by introducing a mutex to prevent races, and a
state-tracking bool so we know whether DRM wishes the output to be
enabled. We choose to use our own mutex rather than ->struct_mutex
so that we can still process interrupts in a timely fashion.
Signed-off-by: Russell King <rmk+kernel@....linux.org.uk>
---
drivers/gpu/drm/bridge/dw_hdmi.c | 29 ++++++++++++++++++++++-------
1 file changed, 22 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/bridge/dw_hdmi.c b/drivers/gpu/drm/bridge/dw_hdmi.c
index 7b8a4e942a71..0ee188930d26 100644
--- a/drivers/gpu/drm/bridge/dw_hdmi.c
+++ b/drivers/gpu/drm/bridge/dw_hdmi.c
@@ -125,6 +125,9 @@ struct dw_hdmi {
bool sink_is_hdmi;
bool sink_has_audio;
+ struct mutex mutex; /* for state below and previous_mode */
+ bool disabled; /* DRM has disabled our bridge */
+
spinlock_t audio_lock;
struct mutex audio_mutex;
unsigned int sample_rate;
@@ -1389,8 +1392,12 @@ static void dw_hdmi_bridge_mode_set(struct drm_bridge *bridge,
{
struct dw_hdmi *hdmi = bridge->driver_private;
+ mutex_lock(&hdmi->mutex);
+
/* Store the display mode for plugin/DKMS poweron events */
memcpy(&hdmi->previous_mode, mode, sizeof(hdmi->previous_mode));
+
+ mutex_unlock(&hdmi->mutex);
}
static bool dw_hdmi_bridge_mode_fixup(struct drm_bridge *bridge,
@@ -1404,14 +1411,20 @@ static void dw_hdmi_bridge_disable(struct drm_bridge *bridge)
{
struct dw_hdmi *hdmi = bridge->driver_private;
+ mutex_lock(&hdmi->mutex);
+ hdmi->disabled = true;
dw_hdmi_poweroff(hdmi);
+ mutex_unlock(&hdmi->mutex);
}
static void dw_hdmi_bridge_enable(struct drm_bridge *bridge)
{
struct dw_hdmi *hdmi = bridge->driver_private;
+ mutex_lock(&hdmi->mutex);
dw_hdmi_poweron(hdmi);
+ hdmi->disabled = false;
+ mutex_unlock(&hdmi->mutex);
}
static void dw_hdmi_bridge_nop(struct drm_bridge *bridge)
@@ -1534,20 +1547,20 @@ static irqreturn_t dw_hdmi_irq(int irq, void *dev_id)
phy_int_pol = hdmi_readb(hdmi, HDMI_PHY_POL0);
if (intr_stat & HDMI_IH_PHY_STAT0_HPD) {
+ hdmi_modb(hdmi, ~phy_int_pol, HDMI_PHY_HPD, HDMI_PHY_POL0);
+ mutex_lock(&hdmi->mutex);
if (phy_int_pol & HDMI_PHY_HPD) {
dev_dbg(hdmi->dev, "EVENT=plugin\n");
- hdmi_modb(hdmi, 0, HDMI_PHY_HPD, HDMI_PHY_POL0);
-
- dw_hdmi_poweron(hdmi);
+ if (!hdmi->disabled)
+ dw_hdmi_poweron(hdmi);
} else {
dev_dbg(hdmi->dev, "EVENT=plugout\n");
- hdmi_modb(hdmi, HDMI_PHY_HPD, HDMI_PHY_HPD,
- HDMI_PHY_POL0);
-
- dw_hdmi_poweroff(hdmi);
+ if (!hdmi->disabled)
+ dw_hdmi_poweroff(hdmi);
}
+ mutex_unlock(&hdmi->mutex);
drm_helper_hpd_irq_event(hdmi->bridge->dev);
}
@@ -1617,7 +1630,9 @@ int dw_hdmi_bind(struct device *dev, struct device *master,
hdmi->sample_rate = 48000;
hdmi->ratio = 100;
hdmi->encoder = encoder;
+ hdmi->disabled = true;
+ mutex_init(&hdmi->mutex);
mutex_init(&hdmi->audio_mutex);
spin_lock_init(&hdmi->audio_lock);
--
2.1.0
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists