diff options
| author | Tomi Valkeinen <tomi.valkeinen@ti.com> | 2017-06-13 12:02:10 +0300 |
|---|---|---|
| committer | Tomi Valkeinen <tomi.valkeinen@ti.com> | 2017-08-23 12:22:09 +0300 |
| commit | 0c43f1e02598d304d4cfb06187305445c8207675 (patch) | |
| tree | 882a3af2f67b84292cfdff5db2961ab69219b865 /drivers/gpu/drm/omapdrm/dss/pll.c | |
| parent | beea6214d1cc5bb08ce25ffe06b57fb948445bed (diff) | |
drm/omap: fix i886 work-around
7d267f068a8b4944d52e8b0ae4c8fcc1c1c5c5ba ("drm/omap: work-around for
errata i886") changed how the PLL dividers and multipliers are
calculated. While the new way should work fine for all the PLLs, it
breaks omap5 PLLs. The issues seen are rather odd: seemed that the
output clock rate is half of what we asked. It is unclear what's causing
there issues.
As a work-around this patch adds a "errata_i886" flag, which is set only
for DRA7's PLLs, and the PLL setup is done according to that flag.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Tested-by: H. Nikolaus Schaller <hns@goldelico.com>
Diffstat (limited to 'drivers/gpu/drm/omapdrm/dss/pll.c')
| -rw-r--r-- | drivers/gpu/drm/omapdrm/dss/pll.c | 29 |
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)) |