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

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>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Ville Syrjälä 2013-09-06 23:28:58 +03:00 committed by Daniel Vetter
parent 8e8f8aec2a
commit 1041a02f35
1 changed files with 7 additions and 8 deletions
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15
drivers/gpu/drm/i915/intel_display.c
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@ -7334,20 +7334,18 @@ 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
*/
/*
@ -7369,10 +7367,11 @@ 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. */