Re: [RFC PATCH 1/3] clk: imx: clk-fracn-gppll: Do not access num/denom register for integer PLL
From: Peng Fan <hidden>
Date: 2025-02-14 03:22:52
Also in:
imx, linux-clk, lkml
On Mon, Feb 10, 2025 at 05:00:09PM +0100, Alexander Stein wrote:
Similar to clk_fracn_gppll_set_rate(), do not access the numerator and denominator register for integer PLL. Set MFD/MFN to 0 instead, so the table lookup will match.
For integer, the calculation will not take mfn/mfi into consideration. Do you see this in test or just code inspection?
quoted hunk ↗ jump to hunk
See i.MX93 RM section 74.5.2.1 (PLL memory map) for ARMPLL, addresses 0x40 and 0x50 are not listed/reserved. Signed-off-by: Alexander Stein <redacted> --- drivers/clk/imx/clk-fracn-gppll.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-)diff --git a/drivers/clk/imx/clk-fracn-gppll.c b/drivers/clk/imx/clk-fracn-gppll.c index 85771afd4698a..3aef548110e25 100644 --- a/drivers/clk/imx/clk-fracn-gppll.c +++ b/drivers/clk/imx/clk-fracn-gppll.c@@ -154,17 +154,24 @@ static unsigned long clk_fracn_gppll_recalc_rate(struct clk_hw *hw, unsigned lon{ struct clk_fracn_gppll *pll = to_clk_fracn_gppll(hw); const struct imx_fracn_gppll_rate_table *rate_table = pll->rate_table; - u32 pll_numerator, pll_denominator, pll_div; + u32 pll_div; u32 mfi, mfn, mfd, rdiv, odiv; u64 fvco = parent_rate; long rate = 0; int i; - pll_numerator = readl_relaxed(pll->base + PLL_NUMERATOR); - mfn = FIELD_GET(PLL_MFN_MASK, pll_numerator); + if (pll->flags & CLK_FRACN_GPPLL_FRACN) { + u32 pll_numerator, pll_denominator; + + pll_numerator = readl_relaxed(pll->base + PLL_NUMERATOR); + mfn = FIELD_GET(PLL_MFN_MASK, pll_numerator); - pll_denominator = readl_relaxed(pll->base + PLL_DENOMINATOR); - mfd = FIELD_GET(PLL_MFD_MASK, pll_denominator); + pll_denominator = readl_relaxed(pll->base + PLL_DENOMINATOR); + mfd = FIELD_GET(PLL_MFD_MASK, pll_denominator); + } else { + mfd = 0; + mfn = 0; + }
Reading the registers for ARM PLL, should be 0 even RM not list. But it is good that using a check here. So I am ok with this change. Regards, Peng
pll_div = readl_relaxed(pll->base + PLL_DIV); mfi = FIELD_GET(PLL_MFI_MASK, pll_div); -- 2.34.1