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drm/i915: fix up ilk drps/ips locking
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We change the drps/ips sw/hw state from different callers: Our own irq
handler, the external intel-ips module and from process context. Most
of these callers don't take any lock at all.

Protect everything by making the mchdev_lock irqsave and grabbing it in
all relevant callsites. Note that we have to convert a few sleeps in the
drps enable/disable code to delays, but alas, I'm not volunteering to
restructure the code around a few work items.

For paranoia add a spin_locked assert to ironlake_set_drps, too.

v2: Move one access inside the lock protection. Caught by the
dev_priv->ips mass-rename ...

v3: Resolve rebase conflict.

Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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Daniel Vetter committed Aug 9, 2012
1 parent 73edd18 commit 9270388
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Showing 2 changed files with 58 additions and 37 deletions.
12 changes: 11 additions & 1 deletion drivers/gpu/drm/i915/i915_irq.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -296,14 +296,22 @@ static void i915_hotplug_work_func(struct work_struct *work)
drm_helper_hpd_irq_event(dev);
}

/* defined intel_pm.c */
extern spinlock_t mchdev_lock;

static void ironlake_handle_rps_change(struct drm_device *dev)
{
drm_i915_private_t *dev_priv = dev->dev_private;
u32 busy_up, busy_down, max_avg, min_avg;
u8 new_delay = dev_priv->cur_delay;
u8 new_delay;
unsigned long flags;

spin_lock_irqsave(&mchdev_lock, flags);

I915_WRITE16(MEMINTRSTS, I915_READ(MEMINTRSTS));

new_delay = dev_priv->cur_delay;

I915_WRITE16(MEMINTRSTS, MEMINT_EVAL_CHG);
busy_up = I915_READ(RCPREVBSYTUPAVG);
busy_down = I915_READ(RCPREVBSYTDNAVG);
Expand All @@ -326,6 +334,8 @@ static void ironlake_handle_rps_change(struct drm_device *dev)
if (ironlake_set_drps(dev, new_delay))
dev_priv->cur_delay = new_delay;

spin_unlock_irqrestore(&mchdev_lock, flags);

return;
}

Expand Down
83 changes: 47 additions & 36 deletions drivers/gpu/drm/i915/intel_pm.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2160,11 +2160,28 @@ intel_alloc_context_page(struct drm_device *dev)
return NULL;
}

/**
* Lock protecting IPS related data structures
* - i915_mch_dev
* - dev_priv->max_delay
* - dev_priv->min_delay
* - dev_priv->fmax
* - dev_priv->gpu_busy
* - dev_priv->gfx_power
*/
DEFINE_SPINLOCK(mchdev_lock);

/* Global for IPS driver to get at the current i915 device. Protected by
* mchdev_lock. */
static struct drm_i915_private *i915_mch_dev;

bool ironlake_set_drps(struct drm_device *dev, u8 val)
{
struct drm_i915_private *dev_priv = dev->dev_private;
u16 rgvswctl;

assert_spin_locked(&mchdev_lock);

rgvswctl = I915_READ16(MEMSWCTL);
if (rgvswctl & MEMCTL_CMD_STS) {
DRM_DEBUG("gpu busy, RCS change rejected\n");
Expand All @@ -2188,6 +2205,8 @@ static void ironlake_enable_drps(struct drm_device *dev)
u32 rgvmodectl = I915_READ(MEMMODECTL);
u8 fmax, fmin, fstart, vstart;

spin_lock_irq(&mchdev_lock);

/* Enable temp reporting */
I915_WRITE16(PMMISC, I915_READ(PMMISC) | MCPPCE_EN);
I915_WRITE16(TSC1, I915_READ(TSC1) | TSE);
Expand Down Expand Up @@ -2233,9 +2252,9 @@ static void ironlake_enable_drps(struct drm_device *dev)
rgvmodectl |= MEMMODE_SWMODE_EN;
I915_WRITE(MEMMODECTL, rgvmodectl);

if (wait_for((I915_READ(MEMSWCTL) & MEMCTL_CMD_STS) == 0, 10))
if (wait_for_atomic((I915_READ(MEMSWCTL) & MEMCTL_CMD_STS) == 0, 10))
DRM_ERROR("stuck trying to change perf mode\n");
msleep(1);
mdelay(1);

ironlake_set_drps(dev, fstart);

Expand All @@ -2244,12 +2263,18 @@ static void ironlake_enable_drps(struct drm_device *dev)
dev_priv->last_time1 = jiffies_to_msecs(jiffies);
dev_priv->last_count2 = I915_READ(0x112f4);
getrawmonotonic(&dev_priv->last_time2);

spin_unlock_irq(&mchdev_lock);
}

static void ironlake_disable_drps(struct drm_device *dev)
{
struct drm_i915_private *dev_priv = dev->dev_private;
u16 rgvswctl = I915_READ16(MEMSWCTL);
u16 rgvswctl;

spin_lock_irq(&mchdev_lock);

rgvswctl = I915_READ16(MEMSWCTL);

/* Ack interrupts, disable EFC interrupt */
I915_WRITE(MEMINTREN, I915_READ(MEMINTREN) & ~MEMINT_EVAL_CHG_EN);
Expand All @@ -2260,11 +2285,12 @@ static void ironlake_disable_drps(struct drm_device *dev)

/* Go back to the starting frequency */
ironlake_set_drps(dev, dev_priv->fstart);
msleep(1);
mdelay(1);
rgvswctl |= MEMCTL_CMD_STS;
I915_WRITE(MEMSWCTL, rgvswctl);
msleep(1);
mdelay(1);

spin_unlock_irq(&mchdev_lock);
}

/* There's a funny hw issue where the hw returns all 0 when reading from
Expand Down Expand Up @@ -2713,21 +2739,6 @@ static const struct cparams {
{ 0, 800, 231, 23784 },
};

/**
* Lock protecting IPS related data structures
* - i915_mch_dev
* - dev_priv->max_delay
* - dev_priv->min_delay
* - dev_priv->fmax
* - dev_priv->gpu_busy
* - dev_priv->gfx_power
*/
static DEFINE_SPINLOCK(mchdev_lock);

/* Global for IPS driver to get at the current i915 device. Protected by
* mchdev_lock. */
static struct drm_i915_private *i915_mch_dev;

unsigned long i915_chipset_val(struct drm_i915_private *dev_priv)
{
u64 total_count, diff, ret;
Expand Down Expand Up @@ -2978,11 +2989,11 @@ void i915_update_gfx_val(struct drm_i915_private *dev_priv)
if (dev_priv->info->gen != 5)
return;

spin_lock(&mchdev_lock);
spin_lock_irq(&mchdev_lock);

__i915_update_gfx_val(dev_priv);

spin_unlock(&mchdev_lock);
spin_unlock_irq(&mchdev_lock);
}

unsigned long i915_gfx_val(struct drm_i915_private *dev_priv)
Expand Down Expand Up @@ -3033,7 +3044,7 @@ unsigned long i915_read_mch_val(void)
struct drm_i915_private *dev_priv;
unsigned long chipset_val, graphics_val, ret = 0;

spin_lock(&mchdev_lock);
spin_lock_irq(&mchdev_lock);
if (!i915_mch_dev)
goto out_unlock;
dev_priv = i915_mch_dev;
Expand All @@ -3044,7 +3055,7 @@ unsigned long i915_read_mch_val(void)
ret = chipset_val + graphics_val;

out_unlock:
spin_unlock(&mchdev_lock);
spin_unlock_irq(&mchdev_lock);

return ret;
}
Expand All @@ -3060,7 +3071,7 @@ bool i915_gpu_raise(void)
struct drm_i915_private *dev_priv;
bool ret = true;

spin_lock(&mchdev_lock);
spin_lock_irq(&mchdev_lock);
if (!i915_mch_dev) {
ret = false;
goto out_unlock;
Expand All @@ -3071,7 +3082,7 @@ bool i915_gpu_raise(void)
dev_priv->max_delay--;

out_unlock:
spin_unlock(&mchdev_lock);
spin_unlock_irq(&mchdev_lock);

return ret;
}
Expand All @@ -3088,7 +3099,7 @@ bool i915_gpu_lower(void)
struct drm_i915_private *dev_priv;
bool ret = true;

spin_lock(&mchdev_lock);
spin_lock_irq(&mchdev_lock);
if (!i915_mch_dev) {
ret = false;
goto out_unlock;
Expand All @@ -3099,7 +3110,7 @@ bool i915_gpu_lower(void)
dev_priv->max_delay++;

out_unlock:
spin_unlock(&mchdev_lock);
spin_unlock_irq(&mchdev_lock);

return ret;
}
Expand All @@ -3117,7 +3128,7 @@ bool i915_gpu_busy(void)
bool ret = false;
int i;

spin_lock(&mchdev_lock);
spin_lock_irq(&mchdev_lock);
if (!i915_mch_dev)
goto out_unlock;
dev_priv = i915_mch_dev;
Expand All @@ -3126,7 +3137,7 @@ bool i915_gpu_busy(void)
ret |= !list_empty(&ring->request_list);

out_unlock:
spin_unlock(&mchdev_lock);
spin_unlock_irq(&mchdev_lock);

return ret;
}
Expand All @@ -3143,7 +3154,7 @@ bool i915_gpu_turbo_disable(void)
struct drm_i915_private *dev_priv;
bool ret = true;

spin_lock(&mchdev_lock);
spin_lock_irq(&mchdev_lock);
if (!i915_mch_dev) {
ret = false;
goto out_unlock;
Expand All @@ -3156,7 +3167,7 @@ bool i915_gpu_turbo_disable(void)
ret = false;

out_unlock:
spin_unlock(&mchdev_lock);
spin_unlock_irq(&mchdev_lock);

return ret;
}
Expand Down Expand Up @@ -3186,18 +3197,18 @@ void intel_gpu_ips_init(struct drm_i915_private *dev_priv)
{
/* We only register the i915 ips part with intel-ips once everything is
* set up, to avoid intel-ips sneaking in and reading bogus values. */
spin_lock(&mchdev_lock);
spin_lock_irq(&mchdev_lock);
i915_mch_dev = dev_priv;
spin_unlock(&mchdev_lock);
spin_unlock_irq(&mchdev_lock);

ips_ping_for_i915_load();
}

void intel_gpu_ips_teardown(void)
{
spin_lock(&mchdev_lock);
spin_lock_irq(&mchdev_lock);
i915_mch_dev = NULL;
spin_unlock(&mchdev_lock);
spin_unlock_irq(&mchdev_lock);
}
static void intel_init_emon(struct drm_device *dev)
{
Expand Down

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