[PATCH v1 2/9] drm/bridge: tc358768: fix PLL parameters computation

[Francesco Dolcini]

From: Francesco Dolcini <francesco.dolcini at toradex.com>

According to Toshiba documentation the PLL input clock after the divider
should be not less than 4MHz, fix the PLL parameters computation
accordingly.

Fixes: ff1ca6397b1d ("drm/bridge: Add tc358768 driver")
Signed-off-by: Francesco Dolcini <francesco.dolcini at toradex.com>
---
 drivers/gpu/drm/bridge/tc358768.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/tc358768.c b/drivers/gpu/drm/bridge/tc358768.c
index 8f349bf4fc32..e9e3f9e02bba 100644
--- a/drivers/gpu/drm/bridge/tc358768.c
+++ b/drivers/gpu/drm/bridge/tc358768.c
@@ -334,13 +334,17 @@ static int tc358768_calc_pll(struct tc358768_priv *priv,
 		u32 fbd;
 
 		for (fbd = 0; fbd < 512; ++fbd) {
-			u32 pll, diff;
+			u32 pll, diff, pll_in;
 
 			pll = (u32)div_u64((u64)refclk * (fbd + 1), divisor);
 
 			if (pll >= max_pll || pll < min_pll)
 				continue;
 
+			pll_in = (u32)div_u64((u64)refclk, prd + 1);
+			if (pll_in < 4000000)
+				continue;
+
 			diff = max(pll, target_pll) - min(pll, target_pll);
 
 			if (diff < best_diff) {
-- 
2.25.1