diff options
| author | Shobhit Kumar <shobhit.kumar@intel.com> | 2013-12-10 12:14:57 +0530 |
|---|---|---|
| committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2013-12-11 23:52:18 +0100 |
| commit | 8e1eed5aa8fe6cdd2c445b7aded42498523ad4dd (patch) | |
| tree | f17c214f7711f226e9d7ab615a3b2a2bfb0dcc0e /drivers/gpu/drm/i915/intel_dsi_pll.c | |
| parent | 44d4c6eebb2ef04f698c292bb6eda5f2e80c663b (diff) | |
drm/i915: Try harder to get best m, n, p values with minimal error
Basically check for both +ive and -ive deviation from target clock and
pick the one with minimal error. If we get a direct match, break from
loop to acheive some optimization.
v2: Use signed variable for target and calculated dsi clock values
Signed-off-by: Vijayakumar Balakrishnan <vijayakumar.balakrishnan@intel.com>
Signed-off-by: Shobhit Kumar <shobhit.kumar@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Diffstat (limited to 'drivers/gpu/drm/i915/intel_dsi_pll.c')
| -rw-r--r-- | drivers/gpu/drm/i915/intel_dsi_pll.c | 30 |
1 files changed, 20 insertions, 10 deletions
diff --git a/drivers/gpu/drm/i915/intel_dsi_pll.c b/drivers/gpu/drm/i915/intel_dsi_pll.c index 0d1b17fee018..ba79ec19da3b 100644 --- a/drivers/gpu/drm/i915/intel_dsi_pll.c +++ b/drivers/gpu/drm/i915/intel_dsi_pll.c @@ -169,8 +169,8 @@ static int dsi_calc_mnp(u32 dsi_clk, struct dsi_mnp *dsi_mnp) u32 ref_clk; u32 error; u32 tmp_error; - u32 target_dsi_clk; - u32 calc_dsi_clk; + int target_dsi_clk; + int calc_dsi_clk; u32 calc_m; u32 calc_p; u32 m_seed; @@ -184,22 +184,32 @@ static int dsi_calc_mnp(u32 dsi_clk, struct dsi_mnp *dsi_mnp) ref_clk = 25000; target_dsi_clk = dsi_clk; error = 0xFFFFFFFF; + tmp_error = 0xFFFFFFFF; calc_m = 0; calc_p = 0; for (m = 62; m <= 92; m++) { for (p = 2; p <= 6; p++) { - + /* Find the optimal m and p divisors + with minimal error +/- the required clock */ calc_dsi_clk = (m * ref_clk) / p; - if (calc_dsi_clk >= target_dsi_clk) { - tmp_error = calc_dsi_clk - target_dsi_clk; - if (tmp_error < error) { - error = tmp_error; - calc_m = m; - calc_p = p; - } + if (calc_dsi_clk == target_dsi_clk) { + calc_m = m; + calc_p = p; + error = 0; + break; + } else + tmp_error = abs(target_dsi_clk - calc_dsi_clk); + + if (tmp_error < error) { + error = tmp_error; + calc_m = m; + calc_p = p; } } + + if (error == 0) + break; } m_seed = lfsr_converts[calc_m - 62]; |