[4/6] clk: bcm2835: divider value has to be 1 or more

Commit Message

Martin Sperl Feb. 29, 2016, 11:39 a.m. UTC

From: Martin Sperl <[e-mail]>

Current clamping of a normal divider allows a value < 1 to be valid.

A divider of < 1 would actually only be possible if we had a PLL...

So this patch clamps the divider to 1.

Fixes: 41691b8862e2 ("clk: bcm2835: Add support for programming the
audio domain clocks")

Signed-off-by: Martin Sperl <[e-mail]>
---
 drivers/clk/bcm/clk-bcm2835.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--
1.7.10.4

Comments

Eric Anholt Feb. 29, 2016, 8:11 p.m. UTC | #1

[e-mail] writes:

> From: Martin Sperl <[e-mail]>
>
> Current clamping of a normal divider allows a value < 1 to be valid.
>
> A divider of < 1 would actually only be possible if we had a PLL...
>
> So this patch clamps the divider to 1.
>
> Fixes: 41691b8862e2 ("clk: bcm2835: Add support for programming the
> audio domain clocks")
>
> Signed-off-by: Martin Sperl <[e-mail]>

Reviewed-by: Eric Anholt <[e-mail]>

Patch

diff --git a/drivers/clk/bcm/clk-bcm2835.c b/drivers/clk/bcm/clk-bcm2835.c
index 1fbb55d..edb1f74 100644
--- a/drivers/clk/bcm/clk-bcm2835.c
+++ b/drivers/clk/bcm/clk-bcm2835.c
@@ -1194,8 +1194,9 @@  static u32 bcm2835_clock_choose_div(struct clk_hw *hw,
 		div += unused_frac_mask + 1;
 	div &= ~unused_frac_mask;

-	/* Clamp to the limits. */
-	div = max(div, unused_frac_mask + 1);
+	/* clamp to min divider of 1 */
+	div = max_t(u32, div, 1 << CM_DIV_FRAC_BITS);
+	/* clamp to the highest possible fractional divider */
 	div = min_t(u32, div, GENMASK(data->int_bits + CM_DIV_FRAC_BITS - 1,
 				      CM_DIV_FRAC_BITS - data->frac_bits));