[PATCH 01/11] drm/i915: Don't factor in pixel multplier when deriving dotclock from link clock and M/N values

ville.syrjala
2013-09-06T20:29:18Z

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

We feed the non-multiplied clock to intel_link_compute_m_n(), so the
opposite operation should use the same order of operations. So we just
multiply by pixel_multiplier in the end now.

Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
drivers/gpu/drm/i915/intel_display.c | 15 +++++++--------
1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index d88057e..b45c6e6 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -7340,20 +7340,18 @@ static void ironlake_crtc_clock_get(struct intel_crtc *crtc,
struct drm_device *dev = crtc->base.dev;
struct drm_i915_private *dev_priv = dev->dev_private;
enum transcoder cpu_transcoder = pipe_config->cpu_transcoder;
- int link_freq, repeat;
+ int link_freq;
u64 clock;
u32 link_m, link_n;

- repeat = pipe_config->pixel_multiplier;
-
/*
* The calculation for the data clock is:
- * pixel_clock = ((m/n)*(link_clock * nr_lanes * repeat))/bpp
+ * pixel_clock = ((m/n)*(link_clock * nr_lanes))/bpp
* But we want to avoid losing precison if possible, so:
- * pixel_clock = ((m * link_clock * nr_lanes * repeat)/(n*bpp))
+ * pixel_clock = ((m * link_clock * nr_lanes)/(n*bpp))
*
* and the link clock is simpler:
- * link_clock = (m * link_clock * repeat) / n
+ * link_clock = (m * link_clock) / n
*/

/*
@@ -7375,10 +7373,11 @@ static void ironlake_crtc_clock_get(struct intel_crtc *crtc,
if (!link_m || !link_n)
return;

- clock = ((u64)link_m * (u64)link_freq * (u64)repeat);
+ clock = ((u64)link_m * (u64)link_freq);
do_div(clock, link_n);

- pipe_config->adjusted_mode.clock = clock;
+ pipe_config->adjusted_mode.clock = clock *
+ pipe_config->pixel_multiplier;
}

/** Returns the currently programmed mode of the given pipe. */
--
1.8.1.5