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authorRussell King <rmk+kernel@arm.linux.org.uk>2015-06-06 21:41:09 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2015-09-15 16:19:48 +0100
commit0fc6f44d9683c61678da4b0eebc89e8fa624de39 (patch)
treebf0e5d5e975a34c36e352d48609e0a1df7e871c8 /drivers/gpu/drm/i2c
parentf84a97d4804a09240372dc7b195f9d6162152228 (diff)
downloadop-kernel-dev-0fc6f44d9683c61678da4b0eebc89e8fa624de39.zip
op-kernel-dev-0fc6f44d9683c61678da4b0eebc89e8fa624de39.tar.gz
drm/i2c: tda998x: re-implement "Fix EDID read timeout on HDMI connect"
Commit 6833d26ef823 ("drm: tda998x: Fix EDID read timeout on HDMI connect") used a weak scheme to try and delay reading EDID on a HDMI connect event. It is weak because delaying the notification of a hotplug event does not stop userspace from trying to read the EDID within the 100ms delay. The solution provided here solves this issue: * When a HDMI connection event is detected, mark a blocking flag for EDID reads, and start a timer for the delay. * If an EDID read is attempted, and the blocking flag is set, wait for the blocking flag to clear. * When the timer expires, clear the blocking flag and wake any thread waiting for the EDID read. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'drivers/gpu/drm/i2c')
-rw-r--r--drivers/gpu/drm/i2c/tda998x_drv.c80
1 files changed, 68 insertions, 12 deletions
diff --git a/drivers/gpu/drm/i2c/tda998x_drv.c b/drivers/gpu/drm/i2c/tda998x_drv.c
index ad3ce34..a53696f 100644
--- a/drivers/gpu/drm/i2c/tda998x_drv.c
+++ b/drivers/gpu/drm/i2c/tda998x_drv.c
@@ -34,7 +34,6 @@ struct tda998x_priv {
struct i2c_client *cec;
struct i2c_client *hdmi;
struct mutex mutex;
- struct delayed_work dwork;
uint16_t rev;
uint8_t current_page;
int dpms;
@@ -47,6 +46,11 @@ struct tda998x_priv {
wait_queue_head_t wq_edid;
volatile int wq_edid_wait;
struct drm_encoder *encoder;
+
+ struct work_struct detect_work;
+ struct timer_list edid_delay_timer;
+ wait_queue_head_t edid_delay_waitq;
+ bool edid_delay_active;
};
#define to_tda998x_priv(x) ((struct tda998x_priv *)to_encoder_slave(x)->slave_priv)
@@ -551,15 +555,50 @@ tda998x_reset(struct tda998x_priv *priv)
reg_write(priv, REG_MUX_VP_VIP_OUT, 0x24);
}
-/* handle HDMI connect/disconnect */
-static void tda998x_hpd(struct work_struct *work)
+/*
+ * The TDA998x has a problem when trying to read the EDID close to a
+ * HPD assertion: it needs a delay of 100ms to avoid timing out while
+ * trying to read EDID data.
+ *
+ * However, tda998x_encoder_get_modes() may be called at any moment
+ * after tda998x_encoder_detect() indicates that we are connected, so
+ * we need to delay probing modes in tda998x_encoder_get_modes() after
+ * we have seen a HPD inactive->active transition. This code implements
+ * that delay.
+ */
+static void tda998x_edid_delay_done(unsigned long data)
+{
+ struct tda998x_priv *priv = (struct tda998x_priv *)data;
+
+ priv->edid_delay_active = false;
+ wake_up(&priv->edid_delay_waitq);
+ schedule_work(&priv->detect_work);
+}
+
+static void tda998x_edid_delay_start(struct tda998x_priv *priv)
+{
+ priv->edid_delay_active = true;
+ mod_timer(&priv->edid_delay_timer, jiffies + HZ/10);
+}
+
+static int tda998x_edid_delay_wait(struct tda998x_priv *priv)
+{
+ return wait_event_killable(priv->edid_delay_waitq, !priv->edid_delay_active);
+}
+
+/*
+ * We need to run the KMS hotplug event helper outside of our threaded
+ * interrupt routine as this can call back into our get_modes method,
+ * which will want to make use of interrupts.
+ */
+static void tda998x_detect_work(struct work_struct *work)
{
- struct delayed_work *dwork = to_delayed_work(work);
struct tda998x_priv *priv =
- container_of(dwork, struct tda998x_priv, dwork);
+ container_of(work, struct tda998x_priv, detect_work);
+ struct drm_device *dev = priv->encoder->dev;
- if (priv->encoder->dev)
- drm_kms_helper_hotplug_event(priv->encoder->dev);
+ if (dev)
+ drm_kms_helper_hotplug_event(dev);
}
/*
@@ -585,7 +624,11 @@ static irqreturn_t tda998x_irq_thread(int irq, void *data)
wake_up(&priv->wq_edid);
handled = true;
} else if (cec != 0) { /* HPD change */
- schedule_delayed_work(&priv->dwork, HZ/10);
+ if (lvl & CEC_RXSHPDLEV_HPD)
+ tda998x_edid_delay_start(priv);
+ else
+ schedule_work(&priv->detect_work);
+
handled = true;
}
return IRQ_RETVAL(handled);
@@ -1103,6 +1146,14 @@ tda998x_encoder_get_modes(struct tda998x_priv *priv,
struct edid *edid;
int n;
+ /*
+ * If we get killed while waiting for the HPD timeout, return
+ * no modes found: we are not in a restartable path, so we
+ * can't handle signals gracefully.
+ */
+ if (tda998x_edid_delay_wait(priv))
+ return 0;
+
if (priv->rev == TDA19988)
reg_clear(priv, REG_TX4, TX4_PD_RAM);
@@ -1149,10 +1200,12 @@ static void tda998x_destroy(struct tda998x_priv *priv)
/* disable all IRQs and free the IRQ handler */
cec_write(priv, REG_CEC_RXSHPDINTENA, 0);
reg_clear(priv, REG_INT_FLAGS_2, INT_FLAGS_2_EDID_BLK_RD);
- if (priv->hdmi->irq) {
+
+ if (priv->hdmi->irq)
free_irq(priv->hdmi->irq, priv);
- cancel_delayed_work_sync(&priv->dwork);
- }
+
+ del_timer_sync(&priv->edid_delay_timer);
+ cancel_work_sync(&priv->detect_work);
i2c_unregister_device(priv->cec);
}
@@ -1253,6 +1306,10 @@ static int tda998x_create(struct i2c_client *client, struct tda998x_priv *priv)
priv->dpms = DRM_MODE_DPMS_OFF;
mutex_init(&priv->mutex); /* protect the page access */
+ init_waitqueue_head(&priv->edid_delay_waitq);
+ setup_timer(&priv->edid_delay_timer, tda998x_edid_delay_done,
+ (unsigned long)priv);
+ INIT_WORK(&priv->detect_work, tda998x_detect_work);
/* wake up the device: */
cec_write(priv, REG_CEC_ENAMODS,
@@ -1311,7 +1368,6 @@ static int tda998x_create(struct i2c_client *client, struct tda998x_priv *priv)
/* init read EDID waitqueue and HDP work */
init_waitqueue_head(&priv->wq_edid);
- INIT_DELAYED_WORK(&priv->dwork, tda998x_hpd);
/* clear pending interrupts */
reg_read(priv, REG_INT_FLAGS_0);
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