This back ported patch fixed the following bug:
Lenovo M4400s Screen will blink between normal and green
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1212376
commit a65851af59387146a28a928c3e7bb17dabc5db72 in upstream
[PATCH] drm/i915: Make data/link N value power of two
The BIOS uses power of two values for the data/link N value.
Follow suit to make the Zotac DP to dual-HDMI dongle work.
v2: Clean up the magic numbers and defines
Change the N clamping to be a bit easier on the eye
Rename intel_reduce_ratio to intel_reduce_m_n_ratio
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=49402
Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=59810
Tested-by: Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx>
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
>From dcfaa8a704152ce020a0594b461d17dd4e07aa9b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <ville.syrjala@xxxxxxxxxxxxxxx>
Date: Tue, 23 Apr 2013 15:03:34 +0300
Subject: [PATCH] drm/i915: Make data/link N value power of two
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commit a65851af59387146a28a928c3e7bb17dabc5db72 upstream.
The BIOS uses power of two values for the data/link N value.
Follow suit to make the Zotac DP to dual-HDMI dongle work.
v2: Clean up the magic numbers and defines
Change the N clamping to be a bit easier on the eye
Rename intel_reduce_ratio to intel_reduce_m_n_ratio
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=49402
Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=59810
Tested-by: Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx>
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
[Haitao Zhang: backport to 3.8]
Signed-off-by: Haitao Zhang <haitao.zhang@xxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_reg.h | 12 ++++--------
drivers/gpu/drm/i915/intel_display.c | 23 +++++++++++++++--------
2 files changed, 19 insertions(+), 16 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index ce70f0a..da24f9c 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -2603,14 +2603,14 @@
#define _PIPEB_GMCH_DATA_M 0x71050
/* Transfer unit size for display port - 1, default is 0x3f (for TU size 64) */
-#define PIPE_GMCH_DATA_M_TU_SIZE_MASK (0x3f << 25)
-#define PIPE_GMCH_DATA_M_TU_SIZE_SHIFT 25
+#define TU_SIZE(x) (((x)-1) << 25) /* default size 64 */
+#define TU_SIZE_MASK (0x3f << 25)
-#define PIPE_GMCH_DATA_M_MASK (0xffffff)
+#define DATA_LINK_M_N_MASK (0xffffff)
+#define DATA_LINK_N_MAX (0x800000)
#define _PIPEA_GMCH_DATA_N 0x70054
#define _PIPEB_GMCH_DATA_N 0x71054
-#define PIPE_GMCH_DATA_N_MASK (0xffffff)
/*
* Computing Link M and N values for the Display Port link
@@ -2625,11 +2625,9 @@
#define _PIPEA_DP_LINK_M 0x70060
#define _PIPEB_DP_LINK_M 0x71060
-#define PIPEA_DP_LINK_M_MASK (0xffffff)
#define _PIPEA_DP_LINK_N 0x70064
#define _PIPEB_DP_LINK_N 0x71064
-#define PIPEA_DP_LINK_N_MASK (0xffffff)
#define PIPE_GMCH_DATA_M(pipe) _PIPE(pipe, _PIPEA_GMCH_DATA_M, _PIPEB_GMCH_DATA_M)
#define PIPE_GMCH_DATA_N(pipe) _PIPE(pipe, _PIPEA_GMCH_DATA_N, _PIPEB_GMCH_DATA_N)
@@ -3295,8 +3293,6 @@
#define _PIPEA_DATA_M1 0x60030
-#define TU_SIZE(x) (((x)-1) << 25) /* default size 64 */
-#define TU_SIZE_MASK 0x7e000000
#define PIPE_DATA_M1_OFFSET 0
#define _PIPEA_DATA_N1 0x60034
#define PIPE_DATA_N1_OFFSET 0
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index b17d8a8..594021c 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -4042,26 +4042,33 @@ struct fdi_m_n {
static void
fdi_reduce_ratio(u32 *num, u32 *den)
{
- while (*num > 0xffffff || *den > 0xffffff) {
+ while (*num > DATA_LINK_M_N_MASK ||
+ *den > DATA_LINK_M_N_MASK) {
*num >>= 1;
*den >>= 1;
}
}
+static void compute_m_n(unsigned int m, unsigned int n,
+ uint32_t *ret_m, uint32_t *ret_n)
+{
+ *ret_n = min_t(unsigned int, roundup_pow_of_two(n), DATA_LINK_N_MAX);
+ *ret_m = div_u64((uint64_t) m * *ret_n, n);
+ fdi_reduce_ratio(ret_m, ret_n);
+}
+
static void
ironlake_compute_m_n(int bits_per_pixel, int nlanes, int pixel_clock,
int link_clock, struct fdi_m_n *m_n)
{
m_n->tu = 64; /* default size */
- /* BUG_ON(pixel_clock > INT_MAX / 36); */
- m_n->gmch_m = bits_per_pixel * pixel_clock;
- m_n->gmch_n = link_clock * nlanes * 8;
- fdi_reduce_ratio(&m_n->gmch_m, &m_n->gmch_n);
+ compute_m_n(bits_per_pixel * pixel_clock,
+ link_clock * nlanes * 8,
+ &m_n->gmch_m, &m_n->gmch_n);
- m_n->link_m = pixel_clock;
- m_n->link_n = link_clock;
- fdi_reduce_ratio(&m_n->link_m, &m_n->link_n);
+ compute_m_n(pixel_clock, link_clock,
+ &m_n->link_m, &m_n->link_n);
}
static inline bool intel_panel_use_ssc(struct drm_i915_private *dev_priv)
--
1.7.9.5