[PATCH v2] clk: bcm2835: Clamp the PLL's requested rate to the hardware limits.

From: Eric Anholt
Date: Fri Sep 30 2016 - 13:07:47 EST


Fixes setting low-resolution video modes on HDMI. Now the PLLH_PIX
divider adjusts itself until the PLLH is within bounds.

Signed-off-by: Eric Anholt <eric@xxxxxxxxxx>
---
drivers/clk/bcm/clk-bcm2835.c | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/drivers/clk/bcm/clk-bcm2835.c b/drivers/clk/bcm/clk-bcm2835.c
index 7a7970865c2d..69a1849d140c 100644
--- a/drivers/clk/bcm/clk-bcm2835.c
+++ b/drivers/clk/bcm/clk-bcm2835.c
@@ -499,8 +499,12 @@ static long bcm2835_pll_rate_from_divisors(unsigned long parent_rate,
static long bcm2835_pll_round_rate(struct clk_hw *hw, unsigned long rate,
unsigned long *parent_rate)
{
+ struct bcm2835_pll *pll = container_of(hw, struct bcm2835_pll, hw);
+ const struct bcm2835_pll_data *data = pll->data;
u32 ndiv, fdiv;

+ rate = clamp(rate, data->min_rate, data->max_rate);
+
bcm2835_pll_choose_ndiv_and_fdiv(rate, *parent_rate, &ndiv, &fdiv);

return bcm2835_pll_rate_from_divisors(*parent_rate, ndiv, fdiv, 1);
@@ -605,13 +609,6 @@ static int bcm2835_pll_set_rate(struct clk_hw *hw,
u32 ana[4];
int i;

- if (rate < data->min_rate || rate > data->max_rate) {
- dev_err(cprman->dev, "%s: rate out of spec: %lu vs (%lu, %lu)\n",
- clk_hw_get_name(hw), rate,
- data->min_rate, data->max_rate);
- return -EINVAL;
- }
-
if (rate > data->max_fb_rate) {
use_fb_prediv = true;
rate /= 2;
--
2.9.3