[PATCH 5.17 0746/1126] clk: qcom: clk-rcg2: Update logic to calculate D value for RCG

Greg Kroah-Hartman
2022-04-05T08:37:06Z

From: Taniya Das <tdas@codeaurora.org>

[ Upstream commit 58922910add18583d5273c2edcdb9fd7bf4eca02 ]

The display pixel clock has a requirement on certain newer platforms to
support M/N as (2/3) and the final D value calculated results in
underflow errors.
As the current implementation does not check for D value is within
the accepted range for a given M & N value. Update the logic to
calculate the final D value based on the range.

Fixes: 99cbd064b059f ("clk: qcom: Support display RCG clocks")
Signed-off-by: Taniya Das <tdas@codeaurora.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220227175536.3131-1-tdas@codeaurora.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/clk/qcom/clk-rcg2.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/qcom/clk-rcg2.c b/drivers/clk/qcom/clk-rcg2.c
index e1b1b426fae4..b831975a9606 100644
--- a/drivers/clk/qcom/clk-rcg2.c
+++ b/drivers/clk/qcom/clk-rcg2.c
@@ -264,7 +264,7 @@ static int clk_rcg2_determine_floor_rate(struct clk_hw *hw,

static int __clk_rcg2_configure(struct clk_rcg2 *rcg, const struct freq_tbl *f)
{
- u32 cfg, mask;
+ u32 cfg, mask, d_val, not2d_val, n_minus_m;
struct clk_hw *hw = &rcg->clkr.hw;
int ret, index = qcom_find_src_index(hw, rcg->parent_map, f->src);

@@ -283,8 +283,17 @@ static int __clk_rcg2_configure(struct clk_rcg2 *rcg, const struct freq_tbl *f)
if (ret)
return ret;

+ /* Calculate 2d value */
+ d_val = f->n;
+
+ n_minus_m = f->n - f->m;
+ n_minus_m *= 2;
+
+ d_val = clamp_t(u32, d_val, f->m, n_minus_m);
+ not2d_val = ~d_val & mask;
+
ret = regmap_update_bits(rcg->clkr.regmap,
- RCG_D_OFFSET(rcg), mask, ~f->n);
+ RCG_D_OFFSET(rcg), mask, not2d_val);
if (ret)
return ret;
}
--
2.34.1