[v6,58/84] drm/omap: pll: fix iteration loop check

Commit Message

Tomi Valkeinen Dec. 15, 2020, 10:46 a.m. UTC

If the PLL calc function is given bad parameters, n_start/m_start may be
higher than n_stop/m_stop, which leads to the loops iterating through
the whole u32 number space.

Fix this by failing early on such cases.

Signed-off-by: Tomi Valkeinen <[e-mail]>
Reviewed-by: Laurent Pinchart <[e-mail]>
Reviewed-by: Sebastian Reichel <[e-mail]>
---
 drivers/gpu/drm/omapdrm/dss/pll.c | 6 ++++++
 1 file changed, 6 insertions(+)

Patch

diff --git a/drivers/gpu/drm/omapdrm/dss/pll.c b/drivers/gpu/drm/omapdrm/dss/pll.c
index 241a338ace29..4c8246a3ded9 100644
--- a/drivers/gpu/drm/omapdrm/dss/pll.c
+++ b/drivers/gpu/drm/omapdrm/dss/pll.c
@@ -222,6 +222,9 @@  bool dss_pll_calc_a(const struct dss_pll *pll, unsigned long clkin,
 	n_stop = min((unsigned)(clkin / fint_hw_min), hw->n_max);
 	n_inc = 1;
 
+	if (n_start > n_stop)
+		return false;
+
 	if (hw->errata_i886) {
 		swap(n_start, n_stop);
 		n_inc = -1;
@@ -239,6 +242,9 @@  bool dss_pll_calc_a(const struct dss_pll *pll, unsigned long clkin,
 				hw->m_max);
 		m_inc = 1;
 
+		if (m_start > m_stop)
+			continue;
+
 		if (hw->errata_i886) {
 			swap(m_start, m_stop);
 			m_inc = -1;