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drm/i915: Add setters for min/max frequency

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Provide a standardized sysfs interface for setting min, and max
frequencies.  The code which reads the limits were lifted from the
debugfs files. As a brief explanation, the limits are similar to the CPU
p-states. We have 3 states:

RP0 - ie. max frequency
RP1 - ie. "preferred min" frequency
RPn - seriously lowest frequency

Initially Daniel asked me to clamp the writes to supported values, but
in conforming to the way the cpufreq drivers seem to work, instead
return -EINVAL (noticed by Jesse in discussion).
The values can be used by userspace wishing to control the limits of the
GPU (see the CC list for people who care).

v4: Make exceeding the soft limits return -EINVAL as well (Daniel)

v3: bug fix (Ben) -  was passing the MHz value to gen6_set_rps instead of
the step value. To fix, deal only with step values by doing the divide
at the top.

v2: add the dropped mutex_unlock in error cases (Chris)
EINVAL on both too min, or too max (Daniel)

v2 Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
CC: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Ben Widawsky 2012-09-12 18:12:07 -07:00 committed by Daniel Vetter
parent b6f69c9a7f
commit 46ddf19477
1 changed files with 81 additions and 2 deletions
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83
drivers/gpu/drm/i915/i915_sysfs.c
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@ -238,6 +238,45 @@ static ssize_t gt_max_freq_mhz_show(struct device *kdev, struct device_attribute
return snprintf(buf, PAGE_SIZE, "%d", ret);
}
static ssize_t gt_max_freq_mhz_store(struct device *kdev,
struct device_attribute *attr,
const char *buf, size_t count)
{
struct drm_minor *minor = container_of(kdev, struct drm_minor, kdev);
struct drm_device *dev = minor->dev;
struct drm_i915_private *dev_priv = dev->dev_private;
u32 val, rp_state_cap, hw_max, hw_min;
ssize_t ret;
ret = kstrtou32(buf, 0, &val);
if (ret)
return ret;
val /= GT_FREQUENCY_MULTIPLIER;
ret = mutex_lock_interruptible(&dev->struct_mutex);
if (ret)
return ret;
rp_state_cap = I915_READ(GEN6_RP_STATE_CAP);
hw_max = (rp_state_cap & 0xff);
hw_min = ((rp_state_cap & 0xff0000) >> 16);
if (val < hw_min || val > hw_max || val < dev_priv->rps.min_delay) {
mutex_unlock(&dev->struct_mutex);
return -EINVAL;
}
if (dev_priv->rps.cur_delay > val)
gen6_set_rps(dev_priv->dev, val);
dev_priv->rps.max_delay = val;
mutex_unlock(&dev->struct_mutex);
return count;
}
static ssize_t gt_min_freq_mhz_show(struct device *kdev, struct device_attribute *attr, char *buf)
{
struct drm_minor *minor = container_of(kdev, struct drm_minor, kdev);
@ -255,9 +294,49 @@ static ssize_t gt_min_freq_mhz_show(struct device *kdev, struct device_attribute
return snprintf(buf, PAGE_SIZE, "%d", ret);
}
static ssize_t gt_min_freq_mhz_store(struct device *kdev,
struct device_attribute *attr,
const char *buf, size_t count)
{
struct drm_minor *minor = container_of(kdev, struct drm_minor, kdev);
struct drm_device *dev = minor->dev;
struct drm_i915_private *dev_priv = dev->dev_private;
u32 val, rp_state_cap, hw_max, hw_min;
ssize_t ret;
ret = kstrtou32(buf, 0, &val);
if (ret)
return ret;
val /= GT_FREQUENCY_MULTIPLIER;
ret = mutex_lock_interruptible(&dev->struct_mutex);
if (ret)
return ret;
rp_state_cap = I915_READ(GEN6_RP_STATE_CAP);
hw_max = (rp_state_cap & 0xff);
hw_min = ((rp_state_cap & 0xff0000) >> 16);
if (val < hw_min || val > hw_max || val > dev_priv->rps.max_delay) {
mutex_unlock(&dev->struct_mutex);
return -EINVAL;
}
if (dev_priv->rps.cur_delay < val)
gen6_set_rps(dev_priv->dev, val);
dev_priv->rps.min_delay = val;
mutex_unlock(&dev->struct_mutex);
return count;
}
static DEVICE_ATTR(gt_cur_freq_mhz, S_IRUGO, gt_cur_freq_mhz_show, NULL);
static DEVICE_ATTR(gt_max_freq_mhz, S_IRUGO | S_IWUSR, gt_max_freq_mhz_show, NULL);
static DEVICE_ATTR(gt_min_freq_mhz, S_IRUGO | S_IWUSR, gt_min_freq_mhz_show, NULL);
static DEVICE_ATTR(gt_max_freq_mhz, S_IRUGO | S_IWUSR, gt_max_freq_mhz_show, gt_max_freq_mhz_store);
static DEVICE_ATTR(gt_min_freq_mhz, S_IRUGO | S_IWUSR, gt_min_freq_mhz_show, gt_min_freq_mhz_store);
static const struct attribute *gen6_attrs[] = {
&dev_attr_gt_cur_freq_mhz.attr,