[Intel-gfx] [PATCH 2/2] drm/i915/dp: Dither down to 6bpc if it makes the mode fit
Adam Jackson
ajax at redhat.com
Mon Oct 10 22:33:35 CEST 2011
Some active adaptors (VGA usually) only have two lanes at 2.7GHz.
That's a maximum pixel clock of 144MHz at 8bpc, but 192MHz at 6bpc.
Signed-off-by: Adam Jackson <ajax at redhat.com>
---
drivers/gpu/drm/i915/intel_display.c | 22 ++++++++++++++++++++--
drivers/gpu/drm/i915/intel_dp.c | 31 ++++++++++++++++++++++++-------
drivers/gpu/drm/i915/intel_drv.h | 1 +
3 files changed, 45 insertions(+), 9 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index bd9c878..d563110 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -4591,6 +4591,7 @@ static inline bool intel_panel_use_ssc(struct drm_i915_private *dev_priv)
/**
* intel_choose_pipe_bpp_dither - figure out what color depth the pipe should send
* @crtc: CRTC structure
+ * @mode: requested mode
*
* A pipe may be connected to one or more outputs. Based on the depth of the
* attached framebuffer, choose a good color depth to use on the pipe.
@@ -4602,13 +4603,15 @@ static inline bool intel_panel_use_ssc(struct drm_i915_private *dev_priv)
* HDMI supports only 8bpc or 12bpc, so clamp to 8bpc with dither for 10bpc
* Displays may support a restricted set as well, check EDID and clamp as
* appropriate.
+ * DP may want to dither down to 6bpc to fit larger modes
*
* RETURNS:
* Dithering requirement (i.e. false if display bpc and pipe bpc match,
* true if they don't match).
*/
static bool intel_choose_pipe_bpp_dither(struct drm_crtc *crtc,
- unsigned int *pipe_bpp)
+ unsigned int *pipe_bpp,
+ struct drm_display_mode *mode)
{
struct drm_device *dev = crtc->dev;
struct drm_i915_private *dev_priv = dev->dev_private;
@@ -4679,6 +4682,11 @@ static bool intel_choose_pipe_bpp_dither(struct drm_crtc *crtc,
}
}
+ if (mode->private_flags & INTEL_MODE_DP_FORCE_6BPC) {
+ DRM_DEBUG_KMS("Dithering DP to 6bpc\n");
+ display_bpc = 6;
+ }
+
/*
* We could just drive the pipe at the highest bpc all the time and
* enable dithering as needed, but that costs bandwidth. So choose
@@ -4940,6 +4948,16 @@ static int i9xx_crtc_mode_set(struct drm_crtc *crtc,
pipeconf &= ~PIPECONF_DOUBLE_WIDE;
}
+ /* default to 8bpc */
+ pipeconf &= ~(PIPECONF_BPP_MASK | PIPECONF_DITHER_EN);
+ if (is_dp) {
+ if (mode->private_flags & INTEL_MODE_DP_FORCE_6BPC) {
+ pipeconf |= PIPECONF_BPP_6 |
+ PIPECONF_DITHER_EN |
+ PIPECONF_DITHER_TYPE_ST1;
+ }
+ }
+
dpll |= DPLL_VCO_ENABLE;
DRM_DEBUG_KMS("Mode for pipe %c:\n", pipe == 0 ? 'A' : 'B');
@@ -5335,7 +5353,7 @@ static int ironlake_crtc_mode_set(struct drm_crtc *crtc,
/* determine panel color depth */
temp = I915_READ(PIPECONF(pipe));
temp &= ~PIPE_BPC_MASK;
- dither = intel_choose_pipe_bpp_dither(crtc, &pipe_bpp);
+ dither = intel_choose_pipe_bpp_dither(crtc, &pipe_bpp, mode);
switch (pipe_bpp) {
case 18:
temp |= PIPE_6BPC;
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 44fef5e..da534b4 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -177,13 +177,16 @@ intel_dp_link_clock(uint8_t link_bw)
/* I think this is a fiction */
static int
-intel_dp_link_required(struct drm_device *dev, struct intel_dp *intel_dp, int pixel_clock)
+intel_dp_link_required(struct drm_device *dev, struct intel_dp *intel_dp,
+ int pixel_clock, int check_bpp)
{
struct drm_crtc *crtc = intel_dp->base.base.crtc;
struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
int bpp = 24;
- if (intel_crtc)
+ if (check_bpp)
+ bpp = check_bpp;
+ else if (intel_crtc)
bpp = intel_crtc->bpp;
return (pixel_clock * bpp + 7) / 8;
@@ -215,10 +218,23 @@ intel_dp_mode_valid(struct drm_connector *connector,
/* only refuse the mode on non eDP since we have seen some weird eDP panels
which are outside spec tolerances but somehow work by magic */
- if (!is_edp(intel_dp) &&
- (intel_dp_link_required(connector->dev, intel_dp, mode->clock)
- > intel_dp_max_data_rate(max_link_clock, max_lanes)))
- return MODE_CLOCK_HIGH;
+ if (!is_edp(intel_dp)) {
+ int max_rate = intel_dp_max_data_rate(max_link_clock,
+ max_lanes);
+ int mode_rate = intel_dp_link_required(connector->dev,
+ intel_dp,
+ mode->clock, 0);
+
+ if (mode_rate > max_rate) {
+ mode_rate = intel_dp_link_required(connector->dev,
+ intel_dp,
+ mode->clock, 18);
+ if (mode_rate > max_rate)
+ return MODE_CLOCK_HIGH;
+ else
+ mode->private_flags |= INTEL_MODE_DP_FORCE_6BPC;
+ }
+ }
if (mode->clock < 10000)
return MODE_CLOCK_LOW;
@@ -603,6 +619,7 @@ intel_dp_mode_fixup(struct drm_encoder *encoder, struct drm_display_mode *mode,
int lane_count, clock;
int max_lane_count = intel_dp_max_lane_count(intel_dp);
int max_clock = intel_dp_max_link_bw(intel_dp) == DP_LINK_BW_2_7 ? 1 : 0;
+ int bpp = mode->private_flags & INTEL_MODE_DP_FORCE_6BPC ? 18 : 0;
static int bws[2] = { DP_LINK_BW_1_62, DP_LINK_BW_2_7 };
if (is_edp(intel_dp) && dev_priv->panel_fixed_mode) {
@@ -620,7 +637,7 @@ intel_dp_mode_fixup(struct drm_encoder *encoder, struct drm_display_mode *mode,
for (clock = 0; clock <= max_clock; clock++) {
int link_avail = intel_dp_max_data_rate(intel_dp_link_clock(bws[clock]), lane_count);
- if (intel_dp_link_required(encoder->dev, intel_dp, mode->clock)
+ if (intel_dp_link_required(encoder->dev, intel_dp, mode->clock, bpp)
<= link_avail) {
intel_dp->link_bw = bws[clock];
intel_dp->lane_count = lane_count;
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index fe1099d..edf1adf 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -110,6 +110,7 @@
/* drm_display_mode->private_flags */
#define INTEL_MODE_PIXEL_MULTIPLIER_SHIFT (0x0)
#define INTEL_MODE_PIXEL_MULTIPLIER_MASK (0xf << INTEL_MODE_PIXEL_MULTIPLIER_SHIFT)
+#define INTEL_MODE_DP_FORCE_6BPC (0x10)
static inline void
intel_mode_set_pixel_multiplier(struct drm_display_mode *mode,
--
1.7.6.4
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