[PATCH 20/71] drm/i915/chv: find the best divisor for the target clock v4

ville.syrjala
2014-04-09T10:30:20Z

From: Chon Ming Lee <chon.ming.lee@intel.com>

Based on the chv clock limit, find the best divisor.

The divisor data has been verified with this spreadsheet.
P1273_DPLL_Programming Spreadsheet.

v2: Rebase the code and change the chv_find_best_dpll based on new
standard way to use intel_PLL_is_valid. Besides, clean up some extra
variables.

v3: Ville suggest better fixed point for m2 calculation.

v4: -Add comment for the limit is compute using fast clock. (Ville)
-Don't pass the request clock to chv_clock, as the same function will
be use clock readout, which doens't have request clock. (Ville)
-Add and use DIV_ROUND_CLOSEST_ULL to consistent with other clock
calculation. (Ville)
-Fix the dp m2 after m2 has stored fixed point. (Ville)

Signed-off-by: Chon Ming Lee <chon.ming.lee@intel.com>
[vsyrjala: Avoid div-by-zero in chv_clock()]
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
drivers/gpu/drm/i915/intel_display.c | 86 ++++++++++++++++++++++++++++++++++++
drivers/gpu/drm/i915/intel_dp.c | 21 +++++++++
2 files changed, 107 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index e33667d..d73fec5 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -41,6 +41,9 @@
#include <drm/drm_crtc_helper.h>
#include <linux/dma_remapping.h>

+#define DIV_ROUND_CLOSEST_ULL(ll, d) \
+ ({ unsigned long long _tmp = (ll)+(d)/2; do_div(_tmp, d); _tmp; })
+
static void intel_increase_pllclock(struct drm_crtc *crtc);
static void intel_crtc_update_cursor(struct drm_crtc *crtc, bool on);

@@ -328,6 +331,22 @@ static const intel_limit_t intel_limits_vlv = {
.p2 = { .p2_slow = 2, .p2_fast = 20 }, /* slow=min, fast=max */
};

+static const intel_limit_t intel_limits_chv = {
+ /*
+ * These are the data rate limits (measured in fast clocks)
+ * since those are the strictest limits we have. The fast
+ * clock and actual rate limits are more relaxed, so checking
+ * them would make no difference.
+ */
+ .dot = { .min = 25000 * 5, .max = 540000 * 5},
+ .vco = { .min = 4860000, .max = 6700000 },
+ .n = { .min = 1, .max = 1 },
+ .m1 = { .min = 2, .max = 2 },
+ .m2 = { .min = 24 << 22, .max = 175 << 22 },
+ .p1 = { .min = 2, .max = 4 },
+ .p2 = { .p2_slow = 1, .p2_fast = 14 },
+};
+
static void vlv_clock(int refclk, intel_clock_t *clock)
{
clock->m = clock->m1 * clock->m2;
@@ -412,6 +431,8 @@ static const intel_limit_t *intel_limit(struct drm_crtc *crtc, int refclk)
limit = &intel_limits_pineview_lvds;
else
limit = &intel_limits_pineview_sdvo;
+ } else if (IS_CHERRYVIEW(dev)) {
+ limit = &intel_limits_chv;
} else if (IS_VALLEYVIEW(dev)) {
limit = &intel_limits_vlv;
} else if (!IS_GEN2(dev)) {
@@ -456,6 +477,17 @@ static void i9xx_clock(int refclk, intel_clock_t *clock)
clock->dot = DIV_ROUND_CLOSEST(clock->vco, clock->p);
}

+static void chv_clock(int refclk, intel_clock_t *clock)
+{
+ clock->m = clock->m1 * clock->m2;
+ clock->p = clock->p1 * clock->p2;
+ if (WARN_ON(clock->n == 0 || clock->p == 0))
+ return;
+ clock->vco = DIV_ROUND_CLOSEST_ULL((uint64_t)refclk * clock->m,
+ clock->n << 22);
+ clock->dot = DIV_ROUND_CLOSEST(clock->vco, clock->p);
+}
+
#define INTELPllInvalid(s) do { /* DRM_DEBUG(s); */ return false; } while (0)
/**
* Returns whether the given set of divisors are valid for a given refclk with
@@ -731,6 +763,58 @@ vlv_find_best_dpll(const intel_limit_t *limit, struct drm_crtc *crtc,
return found;
}

+static bool
+chv_find_best_dpll(const intel_limit_t *limit, struct drm_crtc *crtc,
+ int target, int refclk, intel_clock_t *match_clock,
+ intel_clock_t *best_clock)
+{
+ struct drm_device *dev = crtc->dev;
+ intel_clock_t clock;
+ uint64_t m2;
+ int found = false;
+
+ memset(best_clock, 0, sizeof(*best_clock));
+
+ /*
+ * Based on hardware doc, the n always set to 1, and m1 always
+ * set to 2. If requires to support 200Mhz refclk, we need to
+ * revisit this because n may not 1 anymore.
+ */
+ clock.n = 1, clock.m1 = 2;
+ target *= 5; /* fast clock */
+
+ for (clock.p1 = limit->p1.max; clock.p1 >= limit->p1.min; clock.p1--) {
+ for (clock.p2 = limit->p2.p2_fast;
+ clock.p2 >= limit->p2.p2_slow;
+ clock.p2 -= clock.p2 > 10 ? 2 : 1) {
+
+ clock.p = clock.p1 * clock.p2;
+
+ m2 = DIV_ROUND_CLOSEST_ULL(((uint64_t)target * clock.p *
+ clock.n) << 22, refclk * clock.m1);
+
+ if (m2 > INT_MAX/clock.m1)
+ continue;
+
+ clock.m2 = m2;
+
+ chv_clock(refclk, &clock);
+
+ if (!intel_PLL_is_valid(dev, limit, &clock))
+ continue;
+
+ /* based on hardware requirement, prefer bigger p
+ */
+ if (clock.p > best_clock->p) {
+ *best_clock = clock;
+ found = true;
+ }
+ }
+ }
+
+ return found;
+}
+
bool intel_crtc_active(struct drm_crtc *crtc)
{
struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
@@ -11031,6 +11115,8 @@ static void intel_init_display(struct drm_device *dev)

if (HAS_PCH_SPLIT(dev) || IS_G4X(dev))
dev_priv->display.find_dpll = g4x_find_best_dpll;
+ else if (IS_CHERRYVIEW(dev))
+ dev_priv->display.find_dpll = chv_find_best_dpll;
else if (IS_VALLEYVIEW(dev))
dev_priv->display.find_dpll = vlv_find_best_dpll;
else if (IS_PINEVIEW(dev))
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index c33971e..6be7b35 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -64,6 +64,24 @@ static const struct dp_link_dpll vlv_dpll[] = {
{ .p1 = 2, .p2 = 2, .n = 1, .m1 = 2, .m2 = 27 } }
};

+/*
+ * CHV supports eDP 1.4 that have more link rates.
+ * Below only provides the fixed rate but exclude variable rate.
+ */
+static const struct dp_link_dpll chv_dpll[] = {
+ /*
+ * CHV requires to program fractional division for m2.
+ * m2 is stored in fixed point format using formula below
+ * (m2_int << 22) | m2_fraction
+ */
+ { DP_LINK_BW_1_62, /* m2_int = 32, m2_fraction = 1677722 */
+ { .p1 = 4, .p2 = 2, .n = 1, .m1 = 2, .m2 = 0x819999a } },
+ { DP_LINK_BW_2_7, /* m2_int = 27, m2_fraction = 0 */
+ { .p1 = 4, .p2 = 1, .n = 1, .m1 = 2, .m2 = 0x6c00000 } },
+ { DP_LINK_BW_5_4, /* m2_int = 27, m2_fraction = 0 */
+ { .p1 = 2, .p2 = 1, .n = 1, .m1 = 2, .m2 = 0x6c00000 } }
+};
+
/**
* is_edp - is the given port attached to an eDP panel (either CPU or PCH)
* @intel_dp: DP struct
@@ -720,6 +738,9 @@ intel_dp_set_clock(struct intel_encoder *encoder,
} else if (HAS_PCH_SPLIT(dev)) {
divisor = pch_dpll;
count = ARRAY_SIZE(pch_dpll);
+ } else if (IS_CHERRYVIEW(dev)) {
+ divisor = chv_dpll;
+ count = ARRAY_SIZE(chv_dpll);
} else if (IS_VALLEYVIEW(dev)) {
divisor = vlv_dpll;
count = ARRAY_SIZE(vlv_dpll);
--
1.8.3.2