|
On 08/09/2015 12:04 AM, Russell King
wrote:
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@xxxxxxxxxxxxxxxx> --- 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); Just like my reply on 08/12, I thought this could be removed, so poweron/poweroff would only be called with bridge->enable/bridge->disable, them maybe no need mutex here. Best regards, - Yakir } + 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); |
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