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Commit 1041a02f authored by Ville Syrjälä's avatar Ville Syrjälä Committed by Daniel Vetter
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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: default avatarJani Nikula <jani.nikula@intel.com>
Signed-off-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent 8e8f8aec

drivers/gpu/drm/i915/intel_display.c

+7 −8
Original line number Diff line number Diff line
@@ -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. */