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Message-ID: <CAK3cCBxq+nR0ntimjBvirqctXRi6xHTfq80Ei-WZ1ecpOLWqFQ@mail.gmail.com>
Date: Thu, 12 Sep 2013 23:53:26 +0800
From: cinifr <cinifr@...il.com>
To: Mark Rutland <mark.rutland@....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).
Thanks for you advice, you are right, I will reupdate the patch. :)
On 12 September 2013 22:26, Mark Rutland <mark.rutland@....com> wrote:
> 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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