[PATCH 12/14] drm/i915: BDW clock change support

Mika Kahola
2015-04-15T13:09:33Z

Add support for changing cdclk frequency during runtime on BDW. The
procedure is quite a bit different on BDW from the one on HSW, so
add a separate function for it.

Also with IPS enabled the actual pixel rate mustn't exceed 95% of cdclk,
so take that into account when computing the max pixel rate.

v2: Grab rps.hw_lock around sandybridge_pcode_write()
v3: Rebase due to power well vs. .global_resources() reordering

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

v4: Rebased to the latest

Signed-off-by: Mika Kahola <mika.kahola@intel.com>
---
drivers/gpu/drm/i915/i915_reg.h | 1 +
drivers/gpu/drm/i915/intel_display.c | 138 ++++++++++++++++++++++++++++++-----
2 files changed, 122 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 74ff995..782d471 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -6411,6 +6411,7 @@ enum skl_disp_power_wells {
#define GEN6_ENCODE_RC6_VID(mv) (((mv) - 245) / 5)
#define GEN6_DECODE_RC6_VID(vids) (((vids) * 5) + 245)
#define HSW_PCODE_DE_WRITE_FREQ_REQ 0x17
+#define BDW_PCODE_DISPLAY_FREQ_CHANGE_REQ 0x18
#define DISPLAY_IPS_CONTROL 0x19
#define HSW_PCODE_DYNAMIC_DUTY_CYCLE_CONTROL 0x1A
#define GEN6_PCODE_DATA 0x138128
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 35489cd..09f3518 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -5214,7 +5214,22 @@ static void intel_update_max_cdclk(struct drm_device *dev)
{
struct drm_i915_private *dev_priv = dev->dev_private;

- if (IS_HASWELL(dev)) {
+ if (IS_BROADWELL(dev)) {
+ /*
+ * FIXME with extra cooling we can allow
+ * 540 MHz for ULX and 675 Mhz for ULT.
+ * How can we know if extra cooling is
+ * available? PCI ID, VTB, something else?
+ */
+ if (I915_READ(FUSE_STRAP) & HSW_CDCLK_LIMIT)
+ dev_priv->max_cdclk_freq = 450000;
+ else if (IS_BDW_ULX(dev))
+ dev_priv->max_cdclk_freq = 450000;
+ else if (IS_BDW_ULT(dev))
+ dev_priv->max_cdclk_freq = 540000;
+ else
+ dev_priv->max_cdclk_freq = 675000;
+ } else if (IS_HASWELL(dev)) {
if (I915_READ(FUSE_STRAP) & HSW_CDCLK_LIMIT)
dev_priv->max_cdclk_freq = 450000;
else if (IS_HSW_ULX(dev))
@@ -6092,13 +6107,11 @@ static bool pipe_config_supports_ips(struct drm_i915_private *dev_priv,
return true;

/*
- * FIXME if we compare against max we should then
- * increase the cdclk frequency when the current
- * value is too low. The other option is to compare
- * against the cdclk frequency we're going have post
- * modeset (ie. one we computed using other constraints).
- * Need to measure whether using a lower cdclk w/o IPS
- * is better or worse than a higher cdclk w/ IPS.
+ * We compare against max which means we must take
+ * the increased cdclk requirement into account when
+ * calculating the new cdclk.
+ *
+ * Should measure whether using a lower cdclk w/o IPS
*/
return ilk_pipe_pixel_rate(pipe_config) <=
dev_priv->max_cdclk_freq * 95 / 100;
@@ -9082,9 +9095,18 @@ static int ilk_max_pixel_rate(struct drm_i915_private *dev_priv)
int max_pixel_rate = 0;

for_each_intel_crtc(dev, crtc) {
- if (crtc->new_enabled)
- max_pixel_rate = max((int)max_pixel_rate,
- (int)ilk_pipe_pixel_rate(crtc->config));
+ int pixel_rate;
+
+ if (!crtc->new_enabled)
+ continue;
+
+ pixel_rate = ilk_pipe_pixel_rate(crtc->config);
+
+ /* pixel rate mustn't exceed 95% of cdclk with IPS on BDW */
+ if (IS_BROADWELL(dev) && crtc->config->ips_enabled)
+ pixel_rate = DIV_ROUND_UP(pixel_rate * 100, 95);
+
+ max_pixel_rate = max(max_pixel_rate, pixel_rate);
}

return max_pixel_rate;
@@ -9099,7 +9121,9 @@ static int haswell_calc_cdclk(struct drm_i915_private *dev_priv,
* FIXME should also account for plane ratio
* once 64bpp pixel formats are supported.
*/
- if (max_pixel_rate > 450000)
+ if (max_pixel_rate > 540000)
+ cdclk = 675000;
+ else if (max_pixel_rate > 450000)
cdclk = 540000;
else if (max_pixel_rate > 337500 || !IS_HSW_ULX(dev_priv))
cdclk = 450000;
@@ -9164,6 +9188,83 @@ static void haswell_set_cdclk(struct drm_device *dev, int cdclk)
cdclk, dev_priv->cdclk_freq);
}

+static void broadwell_set_cdclk(struct drm_device *dev, int cdclk)
+{
+ struct drm_i915_private *dev_priv = dev->dev_private;
+ uint32_t val, data;
+ int ret;
+
+ if (WARN((I915_READ(LCPLL_CTL) &
+ (LCPLL_PLL_DISABLE | LCPLL_PLL_LOCK |
+ LCPLL_CD_CLOCK_DISABLE | LCPLL_ROOT_CD_CLOCK_DISABLE |
+ LCPLL_CD2X_CLOCK_DISABLE | LCPLL_POWER_DOWN_ALLOW |
+ LCPLL_CD_SOURCE_FCLK)) != LCPLL_PLL_LOCK,
+ "trying to change cdclk frequency with cdclk not enabled\n"))
+ return;
+
+ mutex_lock(&dev_priv->rps.hw_lock);
+ ret = sandybridge_pcode_write(dev_priv,
+ BDW_PCODE_DISPLAY_FREQ_CHANGE_REQ, 0x0);
+ mutex_unlock(&dev_priv->rps.hw_lock);
+ if (ret) {
+ DRM_ERROR("failed to inform pcode about cdclk change\n");
+ return;
+ }
+
+ val = I915_READ(LCPLL_CTL);
+ val |= LCPLL_CD_SOURCE_FCLK;
+ I915_WRITE(LCPLL_CTL, val);
+
+ if (wait_for_atomic_us(I915_READ(LCPLL_CTL) &
+ LCPLL_CD_SOURCE_FCLK_DONE, 1))
+ DRM_ERROR("Switching to FCLK failed\n");
+
+ val = I915_READ(LCPLL_CTL);
+ val &= ~LCPLL_CLK_FREQ_MASK;
+
+ switch (cdclk) {
+ case 450000:
+ val |= LCPLL_CLK_FREQ_450;
+ data = 0;
+ break;
+ case 540000:
+ val |= LCPLL_CLK_FREQ_54O_BDW;
+ data = 1;
+ break;
+ case 337500:
+ val |= LCPLL_CLK_FREQ_337_5_BDW;
+ data = 2;
+ break;
+ case 675000:
+ val |= LCPLL_CLK_FREQ_675_BDW;
+ data = 3;
+ break;
+ default:
+ WARN(1, "invalid cdclk frequency\n");
+ return;
+ }
+
+ I915_WRITE(LCPLL_CTL, val);
+
+ val = I915_READ(LCPLL_CTL);
+ val &= ~LCPLL_CD_SOURCE_FCLK;
+ I915_WRITE(LCPLL_CTL, val);
+
+ if (wait_for_atomic_us((I915_READ(LCPLL_CTL) &
+ LCPLL_CD_SOURCE_FCLK_DONE) == 0, 1))
+ DRM_ERROR("Switching back to LCPLL failed\n");
+
+ mutex_lock(&dev_priv->rps.hw_lock);
+ sandybridge_pcode_write(dev_priv, HSW_PCODE_DE_WRITE_FREQ_REQ, data);
+ mutex_unlock(&dev_priv->rps.hw_lock);
+
+ intel_update_cdclk(dev);
+
+ WARN(cdclk != dev_priv->cdclk_freq,
+ "cdclk requested %d kHz but got %d kHz\n",
+ cdclk, dev_priv->cdclk_freq);
+}
+
static void haswell_modeset_global_pipes(struct drm_atomic_state *state,
unsigned *prepare_pipes)
{
@@ -9189,7 +9290,10 @@ static void haswell_modeset_global_resources(struct drm_atomic_state *state)
int req_cdclk = haswell_calc_cdclk(dev_priv, max_pixel_rate);

if (req_cdclk != dev_priv->cdclk_freq) {
- haswell_set_cdclk(dev, req_cdclk);
+ if (IS_BROADWELL(dev))
+ broadwell_set_cdclk(dev, req_cdclk);
+ else
+ haswell_set_cdclk(dev, req_cdclk);
}
}

@@ -12349,7 +12453,7 @@ static int __intel_set_mode(struct drm_crtc *crtc,
* mode set on this crtc. For other crtcs we need to use the
* adjusted_mode bits in the crtc directly.
*/
- if (IS_VALLEYVIEW(dev) || IS_HASWELL(dev)) {
+ if (IS_VALLEYVIEW(dev) || IS_HASWELL(dev) || IS_BROADWELL(dev)) {
if (IS_VALLEYVIEW(dev))
valleyview_modeset_global_pipes(state, &prepare_pipes);
else
@@ -14387,9 +14491,9 @@ static void intel_init_display(struct drm_device *dev)
dev_priv->display.fdi_link_train = ivb_manual_fdi_link_train;
} else if (IS_HASWELL(dev) || IS_BROADWELL(dev)) {
dev_priv->display.fdi_link_train = hsw_fdi_link_train;
- if (IS_HASWELL(dev))
- dev_priv->display.modeset_global_resources =
- haswell_modeset_global_resources;
+ dev_priv->display.modeset_global_resources =
+ haswell_modeset_global_resources;
+
} else if (IS_VALLEYVIEW(dev)) {
dev_priv->display.modeset_global_resources =
valleyview_modeset_global_resources;