From 1587e689b328702f8d1f64a1e259de1443797f65 Mon Sep 17 00:00:00 2001 From: Marek Vasut Date: Tue, 11 Oct 2022 22:42:44 +0200 Subject: [PATCH] ARM: dts: stm32: Fix and expand PLL configuration comments Fix the frequencies listed in PLL configuration comments to match the actual frequencies programmed into hardware. Furthermore, add a comment which explains how those frequencies are calculated, so it won't be necessary to look it up all over the datasheet and make more mistakes in the calculation in the future. Signed-off-by: Marek Vasut Cc: Patrice Chotard Cc: Patrick Delaunay Reviewed-by: Patrick Delaunay --- arch/arm/dts/stm32mp15xx-dhcom-u-boot.dtsi | 17 ++++++++++++++++- arch/arm/dts/stm32mp15xx-dhcor-u-boot.dtsi | 17 ++++++++++++++++- 2 files changed, 32 insertions(+), 2 deletions(-) diff --git a/arch/arm/dts/stm32mp15xx-dhcom-u-boot.dtsi b/arch/arm/dts/stm32mp15xx-dhcom-u-boot.dtsi index 8a7156c..b72a2f6 100644 --- a/arch/arm/dts/stm32mp15xx-dhcom-u-boot.dtsi +++ b/arch/arm/dts/stm32mp15xx-dhcom-u-boot.dtsi @@ -190,6 +190,21 @@ CLK_LPTIM45_LSE >; + /* + * cfg = < DIVM1 DIVN P Q R PQR(p,q,r) >; + * frac = < f >; + * + * PRQ(p,q,r) ... for p,q,r: 0-output disabled / 1-output enabled + * DIVN ... actually multiplier, but RCC_PLL1CFGR1 calls the field DIVN + * m ... for PLL1,2: m=2 ; for PLL3,4: m=1 + * XTAL = 24 MHz + * + * VCO = ( XTAL / (DIVM1 + 1) ) * m * ( DIVN + 1 + ( f / 8192 ) ) + * P = VCO / (P + 1) + * Q = VCO / (Q + 1) + * R = VCO / (R + 1) + */ + /* VCO = 1066.0 MHz => P = 266 (AXI), Q = 533 (GPU), R = 533 (DDR) */ pll2: st,pll@1 { compatible = "st,stm32mp1-pll"; @@ -208,7 +223,7 @@ u-boot,dm-pre-reloc; }; - /* VCO = 600.0 MHz => P = 50, Q = 50, R = 50 */ + /* VCO = 600.0 MHz => P = 100, Q = 50, R = 50 */ pll4: st,pll@3 { compatible = "st,stm32mp1-pll"; reg = <3>; diff --git a/arch/arm/dts/stm32mp15xx-dhcor-u-boot.dtsi b/arch/arm/dts/stm32mp15xx-dhcor-u-boot.dtsi index 19f4221..25a288b 100644 --- a/arch/arm/dts/stm32mp15xx-dhcor-u-boot.dtsi +++ b/arch/arm/dts/stm32mp15xx-dhcor-u-boot.dtsi @@ -144,6 +144,21 @@ CLK_LPTIM45_LSE >; + /* + * cfg = < DIVM1 DIVN P Q R PQR(p,q,r) >; + * frac = < f >; + * + * PRQ(p,q,r) ... for p,q,r: 0-output disabled / 1-output enabled + * DIVN ... actually multiplier, but RCC_PLL1CFGR1 calls the field DIVN + * m ... for PLL1,2: m=2 ; for PLL3,4: m=1 + * XTAL = 24 MHz + * + * VCO = ( XTAL / (DIVM1 + 1) ) * m * ( DIVN + 1 + ( f / 8192 ) ) + * P = VCO / (P + 1) + * Q = VCO / (Q + 1) + * R = VCO / (R + 1) + */ + /* VCO = 1066.0 MHz => P = 266 (AXI), Q = 533 (GPU), R = 533 (DDR) */ pll2: st,pll@1 { compatible = "st,stm32mp1-pll"; @@ -162,7 +177,7 @@ u-boot,dm-pre-reloc; }; - /* VCO = 600.0 MHz => P = 99, Q = 74, R = 99 */ + /* VCO = 594.0 MHz => P = 99, Q = 74, R = 99 */ pll4: st,pll@3 { compatible = "st,stm32mp1-pll"; reg = <3>; -- 2.7.4