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drm/i915: Changes required to enable DSI Video Mode on CHT
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On CHT, changes are required for calculating the correct m,n & p with
minimal error +/- for the required DSI clock, so that the correct
dividor & ctrl values are written in cck regs for DSI. This patch has
been tested on CHT RVP with 1200 x 1920 panel.

v2 by Jani, rebased on earlier refactoring, original at [1].

[1] http://mid.gmane.org/1431368400-1942-5-git-send-email-rodrigo.vivi@intel.com

Signed-off-by: Gaurav K Singh <gaurav.k.singh@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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Gaurav K Singh authored and Daniel Vetter committed Jul 3, 2015
1 parent 3c5c6d8 commit 20dbe1a
Showing 1 changed file with 20 additions and 6 deletions.
26 changes: 20 additions & 6 deletions drivers/gpu/drm/i915/intel_dsi_pll.c
Original file line number Diff line number Diff line change
Expand Up @@ -157,11 +157,13 @@ static u32 dsi_clk_from_pclk(u32 pclk, int pixel_format, int lane_count)

#endif

static int dsi_calc_mnp(int target_dsi_clk, struct dsi_mnp *dsi_mnp)
static int dsi_calc_mnp(struct drm_i915_private *dev_priv,
struct dsi_mnp *dsi_mnp, int target_dsi_clk)
{
unsigned int calc_m = 0, calc_p = 0;
unsigned int m, n = 1, p;
int ref_clk = 25000;
unsigned int m_min, m_max, p_min = 2, p_max = 6;
unsigned int m, n, p;
int ref_clk;
int delta = target_dsi_clk;
u32 m_seed;

Expand All @@ -171,8 +173,20 @@ static int dsi_calc_mnp(int target_dsi_clk, struct dsi_mnp *dsi_mnp)
return -ECHRNG;
}

for (m = 62; m <= 92 && delta; m++) {
for (p = 2; p <= 6 && delta; p++) {
if (IS_CHERRYVIEW(dev_priv)) {
ref_clk = 100000;
n = 4;
m_min = 70;
m_max = 96;
} else {
ref_clk = 25000;
n = 1;
m_min = 62;
m_max = 92;
}

for (m = m_min; m <= m_max && delta; m++) {
for (p = p_min; p <= p_max && delta; p++) {
/*
* Find the optimal m and p divisors with minimal delta
* +/- the required clock
Expand Down Expand Up @@ -212,7 +226,7 @@ static void vlv_configure_dsi_pll(struct intel_encoder *encoder)
dsi_clk = dsi_clk_from_pclk(intel_dsi->pclk, intel_dsi->pixel_format,
intel_dsi->lane_count);

ret = dsi_calc_mnp(dsi_clk, &dsi_mnp);
ret = dsi_calc_mnp(dev_priv, &dsi_mnp, dsi_clk);
if (ret) {
DRM_DEBUG_KMS("dsi_calc_mnp failed\n");
return;
Expand Down

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