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path: root/drivers/gpu/drm/omapdrm/dss/pll.c
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Diffstat (limited to 'drivers/gpu/drm/omapdrm/dss/pll.c')
-rw-r--r--drivers/gpu/drm/omapdrm/dss/pll.c29
1 files changed, 20 insertions, 9 deletions
diff --git a/drivers/gpu/drm/omapdrm/dss/pll.c b/drivers/gpu/drm/omapdrm/dss/pll.c
index 5e221302768b..9d9d9d42009b 100644
--- a/drivers/gpu/drm/omapdrm/dss/pll.c
+++ b/drivers/gpu/drm/omapdrm/dss/pll.c
@@ -215,8 +215,8 @@ bool dss_pll_calc_a(const struct dss_pll *pll, unsigned long clkin,
dss_pll_calc_func func, void *data)
{
const struct dss_pll_hw *hw = pll->hw;
- int n, n_min, n_max;
- int m, m_min, m_max;
+ int n, n_start, n_stop, n_inc;
+ int m, m_start, m_stop, m_inc;
unsigned long fint, clkdco;
unsigned long pll_hw_max;
unsigned long fint_hw_min, fint_hw_max;
@@ -226,22 +226,33 @@ bool dss_pll_calc_a(const struct dss_pll *pll, unsigned long clkin,
fint_hw_min = hw->fint_min;
fint_hw_max = hw->fint_max;
- n_min = max(DIV_ROUND_UP(clkin, fint_hw_max), 1ul);
- n_max = min((unsigned)(clkin / fint_hw_min), hw->n_max);
+ n_start = max(DIV_ROUND_UP(clkin, fint_hw_max), 1ul);
+ n_stop = min((unsigned)(clkin / fint_hw_min), hw->n_max);
+ n_inc = 1;
+
+ if (hw->errata_i886) {
+ swap(n_start, n_stop);
+ n_inc = -1;
+ }
pll_max = pll_max ? pll_max : ULONG_MAX;
- /* Try to find high N & M to avoid jitter (DRA7 errata i886) */
- for (n = n_max; n >= n_min; --n) {
+ for (n = n_start; n != n_stop; n += n_inc) {
fint = clkin / n;
- m_min = max(DIV_ROUND_UP(DIV_ROUND_UP(pll_min, fint), 2),
+ m_start = max(DIV_ROUND_UP(DIV_ROUND_UP(pll_min, fint), 2),
1ul);
- m_max = min3((unsigned)(pll_max / fint / 2),
+ m_stop = min3((unsigned)(pll_max / fint / 2),
(unsigned)(pll_hw_max / fint / 2),
hw->m_max);
+ m_inc = 1;
+
+ if (hw->errata_i886) {
+ swap(m_start, m_stop);
+ m_inc = -1;
+ }
- for (m = m_max; m >= m_min; --m) {
+ for (m = m_start; m != m_stop; m += m_inc) {
clkdco = 2 * m * fint;
if (func(n, m, fint, clkdco, data))