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drm/i915: Fix FDI M/N setting according with correct color depth

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FDI M/N calculation hasn't taken the current pipe color depth into account,
but always set as 24bpp. This one checks current pipe color depth setting,
and change FDI M/N calculation a little to use bits_per_pixel first, then
convert to bytes_per_pixel later.

This fixes display corrupt issue on Arrandle LVDS with 1600x900 panel
in 18bpp dual-channel mode.

Cc: Stable Team <stable@kernel.org>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
This commit is contained in:
Zhenyu Wang 2009-09-25 08:01:28 +00:00 committed by Eric Anholt
parent c03342fa6d
commit 58a27471d0
2 changed files with 32 additions and 4 deletions
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5
drivers/gpu/drm/i915/i915_reg.h
View File

@ -1782,6 +1782,11 @@
#define PIPE_START_VBLANK_INTERRUPT_STATUS (1UL<<2) /* 965 or later */
#define PIPE_VBLANK_INTERRUPT_STATUS (1UL<<1)
#define PIPE_OVERLAY_UPDATED_STATUS (1UL<<0)
#define PIPE_BPC_MASK (7 << 5) /* Ironlake */
#define PIPE_8BPC (0 << 5)
#define PIPE_10BPC (1 << 5)
#define PIPE_6BPC (2 << 5)
#define PIPE_12BPC (3 << 5)
#define DSPARB 0x70030
#define DSPARB_CSTART_MASK (0x7f << 7)

31
drivers/gpu/drm/i915/intel_display.c
View File

@ -2082,7 +2082,7 @@ fdi_reduce_ratio(u32 *num, u32 *den)
#define LINK_N 0x80000
static void
igdng_compute_m_n(int bytes_per_pixel, int nlanes,
igdng_compute_m_n(int bits_per_pixel, int nlanes,
int pixel_clock, int link_clock,
struct fdi_m_n *m_n)
{
@ -2092,7 +2092,8 @@ igdng_compute_m_n(int bytes_per_pixel, int nlanes,
temp = (u64) DATA_N * pixel_clock;
temp = div_u64(temp, link_clock);
m_n->gmch_m = div_u64(temp * bytes_per_pixel, nlanes);
m_n->gmch_m = div_u64(temp * bits_per_pixel, nlanes);
m_n->gmch_m >>= 3; /* convert to bytes_per_pixel */
m_n->gmch_n = DATA_N;
fdi_reduce_ratio(&m_n->gmch_m, &m_n->gmch_n);
@ -2766,7 +2767,7 @@ static int intel_crtc_mode_set(struct drm_crtc *crtc,
/* FDI link */
if (IS_IGDNG(dev)) {
int lane, link_bw;
int lane, link_bw, bpp;
/* eDP doesn't require FDI link, so just set DP M/N
according to current link config */
if (is_edp) {
@ -2785,7 +2786,29 @@ static int intel_crtc_mode_set(struct drm_crtc *crtc,
lane = 4;
link_bw = 270000;
}
igdng_compute_m_n(3, lane, target_clock,
/* determine panel color depth */
temp = I915_READ(pipeconf_reg);
switch (temp & PIPE_BPC_MASK) {
case PIPE_8BPC:
bpp = 24;
break;
case PIPE_10BPC:
bpp = 30;
break;
case PIPE_6BPC:
bpp = 18;
break;
case PIPE_12BPC:
bpp = 36;
break;
default:
DRM_ERROR("unknown pipe bpc value\n");
bpp = 24;
}
igdng_compute_m_n(bpp, lane, target_clock,
link_bw, &m_n);
}