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path: root/drivers/gpu/drm/i915/intel_display.c
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Diffstat (limited to 'drivers/gpu/drm/i915/intel_display.c')
-rw-r--r--drivers/gpu/drm/i915/intel_display.c31
1 files changed, 23 insertions, 8 deletions
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 92cfcae7b3d8..e59ad8e20256 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -6116,7 +6116,7 @@ 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) {
@@ -6292,7 +6292,8 @@ 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
@@ -6300,9 +6301,11 @@ 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);
@@ -6313,16 +6316,19 @@ 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)
@@ -12384,6 +12390,15 @@ 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;