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drm/i915: Avoid race of intel_crt_detect_hotplug() with HPD interrupt, v2

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An HPD interrupt may fire while we are in a function that changes
the PORT_HOTPLUG_EN register - especially when an HPD interrupt
storm occurs.
Since the interrupt handler changes the enabled HPD lines when it
detects such a storm the read-modify-write cycles may interfere.
To avoid this, shiled the rmw cycles with IRQ save spinlocks.

Changes since v1:
- Implement a function which takes care of accessing PORT_HOTPLUG_EN.

Signed-off-by: Egbert Eich <eich@suse.de>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Egbert Eich 2015-09-23 16:15:27 +02:00 committed by Daniel Vetter
parent 8204502a6a
commit 0706f17c30
3 changed files with 59 additions and 19 deletions
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3
drivers/gpu/drm/i915/i915_drv.h
View File

@ -2742,6 +2742,9 @@ i915_disable_pipestat(struct drm_i915_private *dev_priv, enum pipe pipe,
void valleyview_enable_display_irqs(struct drm_i915_private *dev_priv);
void valleyview_disable_display_irqs(struct drm_i915_private *dev_priv);
void i915_hotplug_interrupt_update(struct drm_i915_private *dev_priv,
uint32_t mask,
uint32_t bits);
void
ironlake_enable_display_irq(struct drm_i915_private *dev_priv, u32 mask);
void

64
drivers/gpu/drm/i915/i915_irq.c
View File

@ -167,6 +167,44 @@ static const u32 hpd_bxt[HPD_NUM_PINS] = {
static void gen6_rps_irq_handler(struct drm_i915_private *dev_priv, u32 pm_iir);
/* For display hotplug interrupt */
static inline void
i915_hotplug_interrupt_update_locked(struct drm_i915_private *dev_priv,
uint32_t mask,
uint32_t bits)
{
uint32_t val;
assert_spin_locked(&dev_priv->irq_lock);
WARN_ON(bits & ~mask);
val = I915_READ(PORT_HOTPLUG_EN);
val &= ~mask;
val |= bits;
I915_WRITE(PORT_HOTPLUG_EN, val);
}
/**
* i915_hotplug_interrupt_update - update hotplug interrupt enable
* @dev_priv: driver private
* @mask: bits to update
* @bits: bits to enable
* NOTE: the HPD enable bits are modified both inside and outside
* of an interrupt context. To avoid that read-modify-write cycles
* interfer, these bits are protected by a spinlock. Since this
* function is usually not called from a context where the lock is
* held already, this function acquires the lock itself. A non-locking
* version is also available.
*/
void i915_hotplug_interrupt_update(struct drm_i915_private *dev_priv,
uint32_t mask,
uint32_t bits)
{
spin_lock_irq(&dev_priv->irq_lock);
i915_hotplug_interrupt_update_locked(dev_priv, mask, bits);
spin_unlock_irq(&dev_priv->irq_lock);
}
/**
* ilk_update_display_irq - update DEIMR
* @dev_priv: driver private
@ -3050,7 +3088,7 @@ static void vlv_display_irq_reset(struct drm_i915_private *dev_priv)
{
enum pipe pipe;
I915_WRITE(PORT_HOTPLUG_EN, 0);
i915_hotplug_interrupt_update(dev_priv, 0xFFFFFFFF, 0);
I915_WRITE(PORT_HOTPLUG_STAT, I915_READ(PORT_HOTPLUG_STAT));
for_each_pipe(dev_priv, pipe)
@ -3466,7 +3504,7 @@ static void vlv_display_irq_postinstall(struct drm_i915_private *dev_priv)
{
dev_priv->irq_mask = ~0;
I915_WRITE(PORT_HOTPLUG_EN, 0);
i915_hotplug_interrupt_update(dev_priv, 0xffffffff, 0);
POSTING_READ(PORT_HOTPLUG_EN);
I915_WRITE(VLV_IIR, 0xffffffff);
@ -3840,7 +3878,7 @@ static void i915_irq_preinstall(struct drm_device * dev)
int pipe;
if (I915_HAS_HOTPLUG(dev)) {
I915_WRITE(PORT_HOTPLUG_EN, 0);
i915_hotplug_interrupt_update(dev_priv, 0xffffffff, 0);
I915_WRITE(PORT_HOTPLUG_STAT, I915_READ(PORT_HOTPLUG_STAT));
}
@ -3874,7 +3912,7 @@ static int i915_irq_postinstall(struct drm_device *dev)
I915_USER_INTERRUPT;
if (I915_HAS_HOTPLUG(dev)) {
I915_WRITE(PORT_HOTPLUG_EN, 0);
i915_hotplug_interrupt_update(dev_priv, 0xffffffff, 0);
POSTING_READ(PORT_HOTPLUG_EN);
/* Enable in IER... */
@ -4036,7 +4074,7 @@ static void i915_irq_uninstall(struct drm_device * dev)
int pipe;
if (I915_HAS_HOTPLUG(dev)) {
I915_WRITE(PORT_HOTPLUG_EN, 0);
i915_hotplug_interrupt_update(dev_priv, 0xffffffff, 0);
I915_WRITE(PORT_HOTPLUG_STAT, I915_READ(PORT_HOTPLUG_STAT));
}
@ -4057,7 +4095,7 @@ static void i965_irq_preinstall(struct drm_device * dev)
struct drm_i915_private *dev_priv = dev->dev_private;
int pipe;
I915_WRITE(PORT_HOTPLUG_EN, 0);
i915_hotplug_interrupt_update(dev_priv, 0xffffffff, 0);
I915_WRITE(PORT_HOTPLUG_STAT, I915_READ(PORT_HOTPLUG_STAT));
I915_WRITE(HWSTAM, 0xeffe);
@ -4118,7 +4156,7 @@ static int i965_irq_postinstall(struct drm_device *dev)
I915_WRITE(IER, enable_mask);
POSTING_READ(IER);
I915_WRITE(PORT_HOTPLUG_EN, 0);
i915_hotplug_interrupt_update(dev_priv, 0xffffffff, 0);
POSTING_READ(PORT_HOTPLUG_EN);
i915_enable_asle_pipestat(dev);
@ -4133,22 +4171,22 @@ static void i915_hpd_irq_setup(struct drm_device *dev)
assert_spin_locked(&dev_priv->irq_lock);
hotplug_en = I915_READ(PORT_HOTPLUG_EN);
hotplug_en &= ~HOTPLUG_INT_EN_MASK;
/* Note HDMI and DP share hotplug bits */
/* enable bits are the same for all generations */
hotplug_en |= intel_hpd_enabled_irqs(dev, hpd_mask_i915);
hotplug_en = intel_hpd_enabled_irqs(dev, hpd_mask_i915);
/* Programming the CRT detection parameters tends
to generate a spurious hotplug event about three
seconds later. So just do it once.
*/
if (IS_G4X(dev))
hotplug_en |= CRT_HOTPLUG_ACTIVATION_PERIOD_64;
hotplug_en &= ~CRT_HOTPLUG_VOLTAGE_COMPARE_MASK;
hotplug_en |= CRT_HOTPLUG_VOLTAGE_COMPARE_50;
/* Ignore TV since it's buggy */
I915_WRITE(PORT_HOTPLUG_EN, hotplug_en);
i915_hotplug_interrupt_update_locked(dev_priv,
(HOTPLUG_INT_EN_MASK
| CRT_HOTPLUG_VOLTAGE_COMPARE_MASK),
hotplug_en);
}
static irqreturn_t i965_irq_handler(int irq, void *arg)
@ -4261,7 +4299,7 @@ static void i965_irq_uninstall(struct drm_device * dev)
if (!dev_priv)
return;
I915_WRITE(PORT_HOTPLUG_EN, 0);
i915_hotplug_interrupt_update(dev_priv, 0xffffffff, 0);
I915_WRITE(PORT_HOTPLUG_STAT, I915_READ(PORT_HOTPLUG_STAT));
I915_WRITE(HWSTAM, 0xffffffff);

11
drivers/gpu/drm/i915/intel_crt.c
View File

@ -376,7 +376,7 @@ static bool intel_crt_detect_hotplug(struct drm_connector *connector)
{
struct drm_device *dev = connector->dev;
struct drm_i915_private *dev_priv = dev->dev_private;
u32 hotplug_en, orig, stat;
u32 stat;
bool ret = false;
int i, tries = 0;
@ -395,12 +395,12 @@ static bool intel_crt_detect_hotplug(struct drm_connector *connector)
tries = 2;
else
tries = 1;
hotplug_en = orig = I915_READ(PORT_HOTPLUG_EN);
hotplug_en |= CRT_HOTPLUG_FORCE_DETECT;
for (i = 0; i < tries ; i++) {
/* turn on the FORCE_DETECT */
I915_WRITE(PORT_HOTPLUG_EN, hotplug_en);
i915_hotplug_interrupt_update(dev_priv,
CRT_HOTPLUG_FORCE_DETECT,
CRT_HOTPLUG_FORCE_DETECT);
/* wait for FORCE_DETECT to go off */
if (wait_for((I915_READ(PORT_HOTPLUG_EN) &
CRT_HOTPLUG_FORCE_DETECT) == 0,
@ -415,8 +415,7 @@ static bool intel_crt_detect_hotplug(struct drm_connector *connector)
/* clear the interrupt we just generated, if any */
I915_WRITE(PORT_HOTPLUG_STAT, CRT_HOTPLUG_INT_STATUS);
/* and put the bits back */
I915_WRITE(PORT_HOTPLUG_EN, orig);
i915_hotplug_interrupt_update(dev_priv, CRT_HOTPLUG_FORCE_DETECT, 0);
return ret;
}