Quoting Krzysztof Kozlowski (2014-07-18 07:36:32) > Enable ARMCLK down feature on all Exynos4 SoCs. The frequency of > ARMCLK will be reduced upon entering idle mode (WFI or WFE). > > The feature behaves like very fast cpufreq ondemand governor. In idle > mode this reduces energy consumption on full frequency chosen by > cpufreq governor by approximately: > - Trats2: 6.5% (153 mA -> 143 mA) > - Trats: 33.0% (180 mA -> 120 mA) > - Gear1: 27.0% (180 mA -> 130 mA)
Nice power savings! Just a quick question on this feature: the clock frequency is changed in hardware as a result of WFI/WFE? And this only happens when all CPUs in a cluster (e.g. all 4 CPUs in Exynos 4412) are in WFI/WFE state? Thanks, Mike > > The patch uses simillar settings as Exynos5250 (clk-exynos5250.c), > except it disables clock up feature and on Exynos4412 ARMCLK down is > enabled for all 4 cores. > > Tested on Trats board (Exynos4210), Trats2 board (Exynos4412) and > Samsung Gear 1 (Exynos4212). > > Signed-off-by: Krzysztof Kozlowski <k.kozlow...@samsung.com> > > --- > > Changes since v1: > 1. Add PWR_CTRL registers to the list of saved clk registers on > Exynos4x12. Suggested by Tomasz Figa. > 2. Disable the clock up feature. (sug. Tomasz Figa) > 3. Use macros for setting clock down ratio. (sug. Tomasz Figa) > 4. Use num_possible_cpus() for exception on Exynos4x12. (sug. Tomasz > Figa) > 5. Enable the clock down feature also on Exynos4210 Trats board. > --- > drivers/clk/samsung/clk-exynos4.c | 46 > +++++++++++++++++++++++++++++++++++++++ > 1 file changed, 46 insertions(+) > > diff --git a/drivers/clk/samsung/clk-exynos4.c > b/drivers/clk/samsung/clk-exynos4.c > index 7f4a473a7ad7..86c7709dc6d6 100644 > --- a/drivers/clk/samsung/clk-exynos4.c > +++ b/drivers/clk/samsung/clk-exynos4.c > @@ -114,11 +114,27 @@ > #define DIV_CPU1 0x14504 > #define GATE_SCLK_CPU 0x14800 > #define GATE_IP_CPU 0x14900 > +#define PWR_CTRL1 0x15020 > +#define E4X12_PWR_CTRL2 0x15024 > #define E4X12_DIV_ISP0 0x18300 > #define E4X12_DIV_ISP1 0x18304 > #define E4X12_GATE_ISP0 0x18800 > #define E4X12_GATE_ISP1 0x18804 > > +/* Below definitions are used for PWR_CTRL settings */ > +#define PWR_CTRL1_CORE2_DOWN_RATIO(x) (((x) & 0x7) << 28) > +#define PWR_CTRL1_CORE1_DOWN_RATIO(x) (((x) & 0x7) << 16) > +#define PWR_CTRL1_DIV2_DOWN_EN (1 << 9) > +#define PWR_CTRL1_DIV1_DOWN_EN (1 << 8) > +#define PWR_CTRL1_USE_CORE3_WFE (1 << 7) > +#define PWR_CTRL1_USE_CORE2_WFE (1 << 6) > +#define PWR_CTRL1_USE_CORE1_WFE (1 << 5) > +#define PWR_CTRL1_USE_CORE0_WFE (1 << 4) > +#define PWR_CTRL1_USE_CORE3_WFI (1 << 3) > +#define PWR_CTRL1_USE_CORE2_WFI (1 << 2) > +#define PWR_CTRL1_USE_CORE1_WFI (1 << 1) > +#define PWR_CTRL1_USE_CORE0_WFI (1 << 0) > + > /* the exynos4 soc type */ > enum exynos4_soc { > EXYNOS4210, > @@ -155,6 +171,7 @@ static unsigned long exynos4210_clk_save[] __initdata = { > E4210_GATE_IP_LCD1, > E4210_GATE_IP_PERIR, > E4210_MPLL_CON0, > + PWR_CTRL1, > }; > > static unsigned long exynos4x12_clk_save[] __initdata = { > @@ -164,6 +181,8 @@ static unsigned long exynos4x12_clk_save[] __initdata = { > E4X12_DIV_ISP, > E4X12_DIV_CAM1, > E4X12_MPLL_CON0, > + PWR_CTRL1, > + E4X12_PWR_CTRL2, > }; > > static unsigned long exynos4_clk_pll_regs[] __initdata = { > @@ -1164,6 +1183,32 @@ static struct samsung_pll_clock > exynos4x12_plls[nr_plls] __initdata = { > VPLL_LOCK, VPLL_CON0, NULL), > }; > > +static void __init exynos4_core_down_clock(enum exynos4_soc soc) > +{ > + unsigned int tmp; > + > + /* > + * Enable arm clock down (in idle) and set arm divider > + * ratios in WFI/WFE state. > + */ > + tmp = (PWR_CTRL1_CORE2_DOWN_RATIO(7) | PWR_CTRL1_CORE1_DOWN_RATIO(7) | > + PWR_CTRL1_DIV2_DOWN_EN | PWR_CTRL1_DIV1_DOWN_EN | > + PWR_CTRL1_USE_CORE1_WFE | PWR_CTRL1_USE_CORE0_WFE | > + PWR_CTRL1_USE_CORE1_WFI | PWR_CTRL1_USE_CORE0_WFI); > + /* On Exynos4412 enable it also on core 2 and 3 */ > + if (num_possible_cpus() == 4) > + tmp |= PWR_CTRL1_USE_CORE3_WFE | PWR_CTRL1_USE_CORE2_WFE | > + PWR_CTRL1_USE_CORE3_WFI | PWR_CTRL1_USE_CORE2_WFI; > + __raw_writel(tmp, reg_base + PWR_CTRL1); > + > + /* > + * Disable the clock up feature on Exynos4x12, in case it was > + * enabled by bootloader. > + */ > + if (exynos4_soc == EXYNOS4X12) > + __raw_writel(0x0, reg_base + E4X12_PWR_CTRL2); > +} > + > /* register exynos4 clocks */ > static void __init exynos4_clk_init(struct device_node *np, > enum exynos4_soc soc) > @@ -1250,6 +1295,7 @@ static void __init exynos4_clk_init(struct device_node > *np, > samsung_clk_register_alias(ctx, exynos4_aliases, > ARRAY_SIZE(exynos4_aliases)); > > + exynos4_core_down_clock(soc); > exynos4_clk_sleep_init(); > > pr_info("%s clocks: sclk_apll = %ld, sclk_mpll = %ld\n" > -- > 1.9.1 > -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html