From: Arnd Bergmann <arnd@arndb.de>
To: Huacai Chen <chenhuacai@loongson.cn>
Cc: Arnd Bergmann <arnd@arndb.de>, Andy Lutomirski <luto@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
David Airlie <airlied@linux.ie>, Jonathan Corbet <corbet@lwn.net>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-arch <linux-arch@vger.kernel.org>,
"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Xuefeng Li <lixuefeng@loongson.cn>,
Yanteng Si <siyanteng@loongson.cn>,
Huacai Chen <chenhuacai@gmail.com>,
Jiaxun Yang <jiaxun.yang@flygoat.com>
Subject: Re: [PATCH V3 20/22] LoongArch: Add multi-processor (SMP) support
Date: Fri, 17 Sep 2021 11:57:04 +0200 [thread overview]
Message-ID: <CAK8P3a0N=SA-E7ChrMrA5Gv6TDMzJ4_QNUN5OzpJWgzyJwcboA@mail.gmail.com> (raw)
In-Reply-To: <20210917035736.3934017-21-chenhuacai@loongson.cn>
On Fri, Sep 17, 2021 at 5:57 AM Huacai Chen <chenhuacai@loongson.cn> wrote:
> +
> +struct task_struct;
> +
> +struct plat_smp_ops {
> + void (*send_ipi_single)(int cpu, unsigned int action);
> + void (*send_ipi_mask)(const struct cpumask *mask, unsigned int action);
> + void (*smp_setup)(void);
> + void (*prepare_cpus)(unsigned int max_cpus);
> + int (*boot_secondary)(int cpu, struct task_struct *idle);
> + void (*init_secondary)(void);
> + void (*smp_finish)(void);
> +#ifdef CONFIG_HOTPLUG_CPU
> + int (*cpu_disable)(void);
> + void (*cpu_die)(unsigned int cpu);
> +#endif
> +};
Do you foresee having more than one implementation of these in the
near future? If not, I would suggest leaving out the extra indirection
and just using direct function calls.
> +#ifdef CONFIG_SMP
> +
> +static inline void plat_smp_setup(void)
> +{
> + extern const struct plat_smp_ops *mp_ops; /* private */
> +
> + mp_ops->smp_setup();
> +}
> +
> +#else /* !CONFIG_SMP */
> +
> +static inline void plat_smp_setup(void) { }
> +
> +#endif /* !CONFIG_SMP */
You could even go further and do what arch/arm64 has, making
SMP support unconditional. This obviously depends on hardware
roadmaps, but if all harfdware you support has multiple cores,
then non-SMP mode just adds complexity.
> +
> +#define MAX_CPUS 64
You CONFIG_NR_CPUS allows up to 256. I think you need to
adjust one of the numbers to match the other, or remove this
definition and just use CONFIG_NR_CPUS directly.
> +
> +static volatile void *ipi_set_regs[MAX_CPUS];
> +static volatile void *ipi_clear_regs[MAX_CPUS];
> +static volatile void *ipi_status_regs[MAX_CPUS];
> +static volatile void *ipi_en_regs[MAX_CPUS];
> +static volatile void *ipi_mailbox_buf[MAX_CPUS];
Why are these 'volatile'? If they are MMIO registers, they
should be __iomem, and accessed using readl()/writel()
etc
Arnd
next prev parent reply other threads:[~2021-09-17 9:57 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-17 3:57 [PATCH V3 00/22] arch: Add basic LoongArch support Huacai Chen
2021-09-17 3:57 ` [PATCH V3 01/22] Documentation: LoongArch: Add basic documentations Huacai Chen
2021-09-23 20:37 ` Pavel Machek
2021-09-24 4:07 ` Huacai Chen
2021-09-23 20:59 ` Pavel Machek
2021-09-24 4:10 ` Huacai Chen
2021-09-24 6:58 ` Pavel Machek
2021-09-24 7:31 ` Huacai Chen
2021-09-17 3:57 ` [PATCH V3 02/22] Documentation/zh_CN: Add basic LoongArch documentations Huacai Chen
2021-09-17 3:57 ` [PATCH V3 03/22] LoongArch: Add elf-related definitions Huacai Chen
2021-09-17 3:57 ` [PATCH V3 04/22] LoongArch: Add writecombine support for drm Huacai Chen
2021-09-17 3:57 ` [PATCH V3 05/22] LoongArch: Add build infrastructure Huacai Chen
2021-09-17 7:53 ` Arnd Bergmann
2021-09-18 4:35 ` Huacai Chen
2021-09-17 3:57 ` [PATCH V3 06/22] LoongArch: Add CPU definition headers Huacai Chen
2021-09-17 3:57 ` [PATCH V3 07/22] LoongArch: Add atomic/locking headers Huacai Chen
2021-09-17 3:57 ` [PATCH V3 08/22] LoongArch: Add other common headers Huacai Chen
2021-09-17 3:57 ` [PATCH V3 09/22] LoongArch: Add boot and setup routines Huacai Chen
2021-09-17 8:11 ` Arnd Bergmann
2021-09-18 4:54 ` Huacai Chen
2021-09-17 3:57 ` [PATCH V3 10/22] LoongArch: Add exception/interrupt handling Huacai Chen
2021-09-17 3:57 ` [PATCH V3 11/22] LoongArch: Add process management Huacai Chen
2021-09-17 3:57 ` [PATCH V3 12/22] LoongArch: Add memory management Huacai Chen
2021-09-17 3:57 ` [PATCH V3 13/22] LoongArch: Add system call support Huacai Chen
2021-09-17 8:24 ` Arnd Bergmann
2021-09-18 6:55 ` Huacai Chen
2021-09-17 3:57 ` [PATCH V3 14/22] LoongArch: Add signal handling support Huacai Chen
2021-09-17 8:26 ` Arnd Bergmann
2021-09-17 21:10 ` Eric W. Biederman
2021-09-18 7:12 ` Huacai Chen
2021-09-19 9:58 ` Arnd Bergmann
2021-09-20 2:36 ` Huacai Chen
2021-09-20 21:14 ` Richard Henderson
2021-09-22 2:43 ` Huacai Chen
2021-09-17 3:57 ` [PATCH V3 15/22] LoongArch: Add elf and module support Huacai Chen
2021-09-17 8:28 ` Arnd Bergmann
2021-09-18 7:14 ` Huacai Chen
2021-09-17 3:57 ` [PATCH V3 16/22] LoongArch: Add misc common routines Huacai Chen
2021-09-17 6:10 ` Christoph Hellwig
2021-09-17 6:36 ` Huacai Chen
2021-09-17 3:57 ` [PATCH V3 17/22] LoongArch: Add some library functions Huacai Chen
2021-09-17 8:33 ` Arnd Bergmann
2021-09-18 7:16 ` Huacai Chen
2021-09-17 3:57 ` [PATCH V3 18/22] LoongArch: Add PCI controller support Huacai Chen
2021-09-17 9:02 ` Arnd Bergmann
2021-09-18 7:36 ` Huacai Chen
2021-09-21 22:36 ` Bjorn Helgaas
2021-09-22 15:33 ` Arnd Bergmann
2021-09-17 3:57 ` [PATCH V3 19/22] LoongArch: Add VDSO and VSYSCALL support Huacai Chen
2021-09-17 3:57 ` [PATCH V3 20/22] LoongArch: Add multi-processor (SMP) support Huacai Chen
2021-09-17 9:57 ` Arnd Bergmann [this message]
2021-09-18 7:22 ` Huacai Chen
2021-09-17 3:57 ` [PATCH V3 21/22] LoongArch: Add Non-Uniform Memory Access (NUMA) support Huacai Chen
2021-09-17 6:15 ` Christoph Hellwig
2021-09-17 6:40 ` Huacai Chen
2021-09-17 3:57 ` [PATCH V3 22/22] LoongArch: Add Loongson-3 default config file Huacai Chen
2021-09-17 9:59 ` [PATCH V3 00/22] arch: Add basic LoongArch support Arnd Bergmann
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