[PATCH 5.4 036/100] clk: ingenic: Fix bugs with divided dividers

Greg Kroah-Hartman
2021-11-24T13:24:05Z

From: Paul Cercueil <paul@crapouillou.net>

[ Upstream commit ed84ef1cd7eddf933d4ffce2caa8161d6f947245 ]

Two fixes in one:

- In the "impose hardware constraints" block, the "logical" divider
value (aka. not translated to the hardware) was clamped to fit in the
register area, but this totally ignored the fact that the divider
value can itself have a fixed divider.

- The code that made sure that the divider value returned by the
function was a multiple of its own fixed divider could result in a
wrong value being calculated, because it was rounded down instead of
rounded up.

Fixes: 4afe2d1a6ed5 ("clk: ingenic: Allow divider value to be divided")
Co-developed-by: Artur Rojek <contact@artur-rojek.eu>
Signed-off-by: Artur Rojek <contact@artur-rojek.eu>
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Link: https://lore.kernel.org/r/20211001172033.122329-1-paul@crapouillou.net
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/clk/ingenic/cgu.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/clk/ingenic/cgu.c b/drivers/clk/ingenic/cgu.c
index 7490d4f4d9366..dff759c0f6193 100644
--- a/drivers/clk/ingenic/cgu.c
+++ b/drivers/clk/ingenic/cgu.c
@@ -426,15 +426,15 @@ ingenic_clk_calc_div(const struct ingenic_cgu_clk_info *clk_info,
}

/* Impose hardware constraints */
- div = min_t(unsigned, div, 1 << clk_info->div.bits);
- div = max_t(unsigned, div, 1);
+ div = clamp_t(unsigned int, div, clk_info->div.div,
+ clk_info->div.div << clk_info->div.bits);

/*
* If the divider value itself must be divided before being written to
* the divider register, we must ensure we don't have any bits set that
* would be lost as a result of doing so.
*/
- div /= clk_info->div.div;
+ div = DIV_ROUND_UP(div, clk_info->div.div);
div *= clk_info->div.div;

return div;
--
2.33.0