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drm/i915/dp: Dither down to 6bpc if it makes the mode fit

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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.

Fixes Asus UX31 panel being black at startup due to no valid modes since
dc22ee6fc1.

v2: Rebased to current code, resulting in the fix applying to EDP panels as
    well.  Also changed from spatio-temporal to just spatial dithering on
    pre-ironlake, to be conssitent (and less visual flicker)

Signed-off-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
Tested-by: Eric Anholt <eric@anholt.net>
Tested-by: Dirk Hohndel <hohndel@infradead.org>
Signed-off-by: Keith Packard <keithp@keithp.com>
This commit is contained in:
Adam Jackson 2011-12-13 15:41:00 -08:00 committed by Keith Packard
parent f45b55575c
commit 3b5c78a35c
3 changed files with 39 additions and 8 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

22
drivers/gpu/drm/i915/intel_display.c
View file

@ -4670,6 +4670,7 @@ 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.
@ -4681,13 +4682,15 @@ 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;
@ -4758,6 +4761,11 @@ 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
@ -5019,6 +5027,16 @@ 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_SP;
}
}
dpll |= DPLL_VCO_ENABLE;
DRM_DEBUG_KMS("Mode for pipe %c:\n", pipe == 0 ? 'A' : 'B');
@ -5480,7 +5498,7 @@ 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;

24
drivers/gpu/drm/i915/intel_dp.c
View file

@ -208,13 +208,15 @@ intel_dp_link_clock(uint8_t link_bw)
*/
static int
intel_dp_link_required(struct intel_dp *intel_dp, int pixel_clock)
intel_dp_link_required(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 + 9) / 10;
@ -233,6 +235,7 @@ intel_dp_mode_valid(struct drm_connector *connector,
struct intel_dp *intel_dp = intel_attached_dp(connector);
int max_link_clock = intel_dp_link_clock(intel_dp_max_link_bw(intel_dp));
int max_lanes = intel_dp_max_lane_count(intel_dp);
int max_rate, mode_rate;
if (is_edp(intel_dp) && intel_dp->panel_fixed_mode) {
if (mode->hdisplay > intel_dp->panel_fixed_mode->hdisplay)
@ -242,9 +245,17 @@ intel_dp_mode_valid(struct drm_connector *connector,
return MODE_PANEL;
}
if (intel_dp_link_required(intel_dp, mode->clock)
> intel_dp_max_data_rate(max_link_clock, max_lanes))
return MODE_CLOCK_HIGH;
mode_rate = intel_dp_link_required(intel_dp, mode->clock, 0);
max_rate = intel_dp_max_data_rate(max_link_clock, max_lanes);
if (mode_rate > max_rate) {
mode_rate = intel_dp_link_required(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;
@ -672,6 +683,7 @@ 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) && intel_dp->panel_fixed_mode) {
@ -689,7 +701,7 @@ 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(intel_dp, mode->clock)
if (intel_dp_link_required(intel_dp, mode->clock, bpp)
<= link_avail) {
intel_dp->link_bw = bws[clock];
intel_dp->lane_count = lane_count;

1
drivers/gpu/drm/i915/intel_drv.h
View file

@ -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,