Merge tag 'platform-drivers-x86-v4.12-2' of git://git.infradead.org/linux-platform...

[karo-tx-linux.git] / drivers / gpu / drm / i915 / intel_display.c

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 3617927af269afb9872b0d5d419873f0945f880c..569717a1272367a91cf682a9cae7640f9ae32777 100644 (file)
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -6101,7 +6101,7 @@ retry:
        pipe_config->fdi_lanes = lane;
 
        intel_link_compute_m_n(pipe_config->pipe_bpp, lane, fdi_dotclock,
-                              link_bw, &pipe_config->fdi_m_n);
+                              link_bw, &pipe_config->fdi_m_n, false);
 
        ret = ironlake_check_fdi_lanes(dev, intel_crtc->pipe, pipe_config);
        if (ret == -EINVAL && pipe_config->pipe_bpp > 6*3) {
@@ -6277,7 +6277,8 @@ intel_reduce_m_n_ratio(uint32_t *num, uint32_t *den)
 }
 
 static void compute_m_n(unsigned int m, unsigned int n,
-                       uint32_t *ret_m, uint32_t *ret_n)
+                       uint32_t *ret_m, uint32_t *ret_n,
+                       bool reduce_m_n)
 {
        /*
         * Reduce M/N as much as possible without loss in precision. Several DP
@@ -6285,9 +6286,11 @@ static void compute_m_n(unsigned int m, unsigned int n,
         * values. The passed in values are more likely to have the least
         * significant bits zero than M after rounding below, so do this first.
         */
-       while ((m & 1) == 0 && (n & 1) == 0) {
-               m >>= 1;
-               n >>= 1;
+       if (reduce_m_n) {
+               while ((m & 1) == 0 && (n & 1) == 0) {
+                       m >>= 1;
+                       n >>= 1;
+               }
        }
 
        *ret_n = min_t(unsigned int, roundup_pow_of_two(n), DATA_LINK_N_MAX);
@@ -6298,16 +6301,19 @@ static void compute_m_n(unsigned int m, unsigned int n,
 void
 intel_link_compute_m_n(int bits_per_pixel, int nlanes,
                       int pixel_clock, int link_clock,
-                      struct intel_link_m_n *m_n)
+                      struct intel_link_m_n *m_n,
+                      bool reduce_m_n)
 {
        m_n->tu = 64;
 
        compute_m_n(bits_per_pixel * pixel_clock,
                    link_clock * nlanes * 8,
-                   &m_n->gmch_m, &m_n->gmch_n);
+                   &m_n->gmch_m, &m_n->gmch_n,
+                   reduce_m_n);
 
        compute_m_n(pixel_clock, link_clock,
-                   &m_n->link_m, &m_n->link_n);
+                   &m_n->link_m, &m_n->link_n,
+                   reduce_m_n);
 }
 
 static inline bool intel_panel_use_ssc(struct drm_i915_private *dev_priv)
@@ -12197,6 +12203,15 @@ static void update_scanline_offset(struct intel_crtc *crtc)
         * type. For DP ports it behaves like most other platforms, but on HDMI
         * there's an extra 1 line difference. So we need to add two instead of
         * one to the value.
+        *
+        * On VLV/CHV DSI the scanline counter would appear to increment
+        * approx. 1/3 of a scanline before start of vblank. Unfortunately
+        * that means we can't tell whether we're in vblank or not while
+        * we're on that particular line. We must still set scanline_offset
+        * to 1 so that the vblank timestamps come out correct when we query
+        * the scanline counter from within the vblank interrupt handler.
+        * However if queried just before the start of vblank we'll get an
+        * answer that's slightly in the future.
         */
        if (IS_GEN2(dev_priv)) {
                const struct drm_display_mode *adjusted_mode = &crtc->config->base.adjusted_mode;