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<div class="moz-cite-prefix">On 08/09/2015 12:04 AM, Russell King
wrote:<br>
</div>
<blockquote cite="mid:E1ZO6bT-0002vk-3d@rmk-PC.arm.linux.org.uk"
type="cite">
<pre wrap="">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 <a class="moz-txt-link-rfc2396E" href="mailto:rmk+kernel@arm.linux.org.uk"><rmk+kernel@arm.linux.org.uk></a>
---
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);</pre>
</blockquote>
<br>
Just like my reply on
<meta http-equiv="content-type" content="text/html; charset=utf-8">
08/12, I thought this could be removed, so poweron/poweroff<br>
would only be called with bridge->enable/bridge->disable, them
maybe no need<br>
mutex here.<br>
<br>
Best regards,<br>
- Yakir<br>
<blockquote cite="mid:E1ZO6bT-0002vk-3d@rmk-PC.arm.linux.org.uk"
type="cite">
<pre wrap="">
}
+ 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);
</pre>
</blockquote>
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