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Date: Thu, 12 Sep 2013 15:26:19 +0100
From: Mark Rutland <mark.rutland@....com>
To: Fan Rong <cinifr@...il.com>
Cc: "coosty@....com" <coosty@....com>,
"maxime.ripard@...e-electrons.com" <maxime.ripard@...e-electrons.com>,
"daniel.lezcano@...aro.org" <daniel.lezcano@...aro.org>,
"linux@....linux.org.uk" <linux@....linux.org.uk>,
"tglx@...utronix.de" <tglx@...utronix.de>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"pawel.moll@....com" <pawel.moll@....com>,
"rob.herring@...xeda.com" <rob.herring@...xeda.com>,
"linux-sunxi@...glegroups.com" <linux-sunxi@...glegroups.com>
Subject: Re: [PATCH 1/4] Add smp support for Allwinner A20(sunxi 7i).
On Thu, Sep 12, 2013 at 07:51:24AM +0100, Fan Rong wrote:
> Signed-off-by: Fan Rong <cinifr@...il.com>
> ---
> arch/arm/mach-sunxi/Makefile | 2 +
> arch/arm/mach-sunxi/headsmp.S | 12 ++
> arch/arm/mach-sunxi/platform.h | 346 ++++++++++++++++++++++++++++++++++++++++
> arch/arm/mach-sunxi/platsmp.c | 166 +++++++++++++++++++
> arch/arm/mach-sunxi/sunxi.c | 4 +
> 5 files changed, 530 insertions(+)
> create mode 100644 arch/arm/mach-sunxi/headsmp.S
> create mode 100644 arch/arm/mach-sunxi/platform.h
> create mode 100644 arch/arm/mach-sunxi/platsmp.c
>
[...]
> +static struct of_device_id sunxi_cc_ids[] = {
> + { .compatible = "allwinner,sun7i-cc"},
> + { /*sentinel*/ }
> +};
NAK - There's no binding document for this in mainline or this series.
> +
> +
> +static void enable_aw_cpu(int cpu)
> +{
> + long paddr;
> + u32 pwr_reg;
> +
> + struct device_node *np;
> + np = of_find_matching_node(NULL, sunxi_cc_ids);
> + cc_base = of_iomap(np, 0);
This seems to get called repeatedly in sunxi7i_boot_secondary, so you're
repeatedly trying to find the cc node and mapping it, but never
unmapping it. That's both a waste of time and a waste of address space.
It would be nicer to map this once at the start. That seems simpler than
stashing the physical address and mapping/unmapping it repeatedly.
smp_boot_secondary.
> + pr_debug("cc_base is %x\n", (unsigned int)cc_base);
> + if (!cc_base) {
You can use %p to print pointers, without casting to an integer type.
> + pr_debug("error map cc configure\n");
> + return;
As this may be called repeatedly, from a function that can return
errors, it would be nice to propagate an error code if there's a
failure.
> + }
> +
> + paddr = virt_to_phys(sun7i_secondary_startup);
> + writel(paddr, cc_base + AW_CPUCFG_P_REG0);
> + /* step1: Assert nCOREPORESET LOW and hold L1RSTDISABLE LOW.
> + Ensure DBGPWRDUP is held LOW to prevent any external
> + debug access to the processor.
> + */
> + /* assert cpu core reset */
> + writel(0, cc_base + CPUX_RESET_CTL(cpu));
> + /* L1RSTDISABLE hold low */
> + pwr_reg = readl(cc_base + AW_CPUCFG_GENCTL);
> + pwr_reg &= ~(1<<cpu);
> + writel(pwr_reg, cc_base + AW_CPUCFG_GENCTL);
> + /* DBGPWRDUP hold low */
> + pwr_reg = readl(cc_base + AW_CPUCFG_DBGCTL1);
> + pwr_reg &= ~(1<<cpu);
> + writel(pwr_reg, cc_base + AW_CPUCFG_DBGCTL1);
> +
> + /* step2: release power clamp */
> + writel(0xff, cc_base + AW_CPU1_PWR_CLAMP);
> + writel(0x7f, cc_base + AW_CPU1_PWR_CLAMP);
> + writel(0x3f, cc_base + AW_CPU1_PWR_CLAMP);
> + writel(0x1f, cc_base + AW_CPU1_PWR_CLAMP);
> + writel(0x0f, cc_base + AW_CPU1_PWR_CLAMP);
> + writel(0x07, cc_base + AW_CPU1_PWR_CLAMP);
> + writel(0x03, cc_base + AW_CPU1_PWR_CLAMP);
> + writel(0x01, cc_base + AW_CPU1_PWR_CLAMP);
> + writel(0x00, cc_base + AW_CPU1_PWR_CLAMP);
> + mdelay(10);
> +
> + /* step3: clear power-off gating */
> + pwr_reg = readl(cc_base + AW_CPU1_PWROFF_REG);
> + pwr_reg &= ~(1);
> + writel(pwr_reg, cc_base + AW_CPU1_PWROFF_REG);
> + mdelay(1);
> +
> + /* step4: de-assert core reset */
> + writel(3, cc_base + CPUX_RESET_CTL(cpu));
> +
> + /* step5: assert DBGPWRDUP signal */
> + pwr_reg = readl(cc_base + AW_CPUCFG_DBGCTL1);
> + pwr_reg |= (1<<cpu);
> + writel(pwr_reg, cc_base + AW_CPUCFG_DBGCTL1);
> +
> +}
> +
> +
> +
> +static void sunxi7i_smp_init_cpus(void)
> +{
> + unsigned int i, ncores;
> +
> +
> + /* HDG: we do not use scu_get_core_count() here as that does not
> + work on the A20 ? */
> +
> + /* Read current CP15 Cache Size ID Register */
Invalid comment. Judging by the encoding, this is the L2CTLR, not the
CCSIDR.
> + asm volatile ("mrc p15, 1, %0, c9, c0, 2" : "=r" (ncores));
> + ncores = ((ncores >> 24) & 0x3) + 1;
> +
> + pr_debug("[%s] ncores=%d\n", __func__, ncores);
> +
> + for (i = 0; i < ncores; i++)
> + set_cpu_possible(i, true);
> +
> +}
Even ignoring the above, as long as your dt is correct
arm_dt_init_cpu_maps (called from stup_arch) will set the cpus as
possible (and handles arbitrary MPIDR values as may be the case in
multi-cluster).
You don't need this function -- please remove it.
> +
> +/*
> + * for arch/arm/kernel/smp.c:smp_prepare_cpus(unsigned int max_cpus)
> + */
> +static void sunxi7i_smp_prepare_cpus(unsigned int max_cpus)
> +{
> + /*
> + * HDG: we do not call scu_enable() here as the sun6i source dump has
> + * a modified arch/arm/kernel/smp_scu.c, where scu_enable() is a nop.
> + */
> +}
A look in smp.c shows smp_prepare_cpus is perfectly happy to not have a
smp_prepare_cpus callback. You don't need this function -- please remove
it.
> +
> +
> +
> +
> +
> +
Why so much space here (and elsewhere)?
> +/*
> + * for linux/arch/arm/kernel/smp.c:__cpu_up(..)
> + */
> +static int sunxi7i_boot_secondary(unsigned int cpu, struct task_struct *idle)
> +{
> + pr_debug("[%s] enter cpu %d\n", __func__, cpu);
> + spin_lock(&boot_lock);
> + enable_aw_cpu(cpu);
This can fail. You should propagate the error when it does.
> + spin_unlock(&boot_lock);
> + return 0;
> +}
> +
> +
> +
> +
> +struct smp_operations sunxi7i_smp_ops __initdata = {
> + .smp_init_cpus = sunxi7i_smp_init_cpus,
> + .smp_prepare_cpus = sunxi7i_smp_prepare_cpus,
> + .smp_boot_secondary = sunxi7i_boot_secondary,
> +};
I believe only smp_boot_secondary is necessary here.
Thanks,
Mark.
> +
> +
> diff --git a/arch/arm/mach-sunxi/sunxi.c b/arch/arm/mach-sunxi/sunxi.c
> index e79fb34..f3594e6 100644
> --- a/arch/arm/mach-sunxi/sunxi.c
> +++ b/arch/arm/mach-sunxi/sunxi.c
> @@ -26,6 +26,9 @@
> #include <asm/mach/map.h>
> #include <asm/system_misc.h>
>
> +#include "platform.h"
> +
> +
> #define SUN4I_WATCHDOG_CTRL_REG 0x00
> #define SUN4I_WATCHDOG_CTRL_RESTART BIT(0)
> #define SUN4I_WATCHDOG_MODE_REG 0x04
> @@ -139,6 +142,7 @@ static const char * const sunxi_board_dt_compat[] = {
> };
>
> DT_MACHINE_START(SUNXI_DT, "Allwinner A1X (Device Tree)")
> + .smp = smp_ops(sunxi7i_smp_ops),
> .init_machine = sunxi_dt_init,
> .init_time = sunxi_timer_init,
> .dt_compat = sunxi_board_dt_compat,
> --
> 1.7.9.5
>
>
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