drm/i915: Add intel_dotclock_calculate()

Extract the code to calculate the dotclock from the link clock and M/N
values into a new function from ironlake_crtc_clock_get().

The new function can be used to calculate the dotclock for both FDI and
DP cases.

Also simplify the code a bit along the way.

v2: Don't forget about non-pch encoders in ironlake_crtc_clock_get()

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 22 insertions, 21 deletions

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 2e74ccce447d..94ef15c87b80 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -7427,16 +7427,9 @@ static void i9xx_crtc_clock_get(struct intel_crtc *crtc,
         pipe_config->adjusted_mode.clock = clock.dot;
 }
 
-static void ironlake_crtc_clock_get(struct intel_crtc *crtc,
-                                    struct intel_crtc_config *pipe_config)
+int intel_dotclock_calculate(int link_freq,
+                             const struct intel_link_m_n *m_n)
 {
-        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;
-        u64 clock;
-        u32 link_m, link_n;
-
         /*
          * The calculation for the data clock is:
          * pixel_clock = ((m/n)*(link_clock * nr_lanes))/bpp
@@ -7447,6 +7440,18 @@ static void ironlake_crtc_clock_get(struct intel_crtc *crtc,
          * link_clock = (m * link_clock) / n
          */
 
+        if (!m_n->link_n)
+                return 0;
+
+        return div_u64((u64)m_n->link_m * link_freq, m_n->link_n);
+}
+
+static void ironlake_crtc_clock_get(struct intel_crtc *crtc,
+                                    struct intel_crtc_config *pipe_config)
+{
+        struct drm_device *dev = crtc->base.dev;
+        int link_freq;
+
         /*
          * We need to get the FDI or DP link clock here to derive
          * the M/N dividers.
@@ -7455,21 +7460,17 @@ static void ironlake_crtc_clock_get(struct intel_crtc *crtc,
          * For DP, it's either 1.62GHz or 2.7GHz.
          * We do our calculations in 10*MHz since we don't need much precison.
          */
-        if (pipe_config->has_pch_encoder)
+        if (pipe_config->has_pch_encoder) {
                 link_freq = intel_fdi_link_freq(dev) * 10000;
-        else
-                link_freq = pipe_config->port_clock;
 
-        link_m = I915_READ(PIPE_LINK_M1(cpu_transcoder));
-        link_n = I915_READ(PIPE_LINK_N1(cpu_transcoder));
-
-        if (!link_m || !link_n)
-                return;
-
-        clock = ((u64)link_m * (u64)link_freq);
-        do_div(clock, link_n);
+                pipe_config->adjusted_mode.clock =
+                        intel_dotclock_calculate(link_freq, &pipe_config->fdi_m_n);
+        } else {
+                link_freq = pipe_config->port_clock;
 
-        pipe_config->adjusted_mode.clock = clock;
+                pipe_config->adjusted_mode.clock =
+                        intel_dotclock_calculate(link_freq, &pipe_config->dp_m_n);
+        }
 }
 
 /** Returns the currently programmed mode of the given pipe. */