From: swarren@wwwdotorg•org (Stephen Warren)
To: linux-arm-kernel@lists•infradead.org
Subject: [v2 3/9] ARM: tegra: # of CPU cores detection w/ & w/o HAVE_ARM_SCU
Date: Thu, 10 Jan 2013 09:54:13 -0700 [thread overview]
Message-ID: <50EEF235.7070200@wwwdotorg.org> (raw)
In-Reply-To: <20130110.145813.1159140334089730421.hdoyu@nvidia.com>
On 01/10/2013 05:58 AM, Hiroshi Doyu wrote:
> Lorenzo Pieralisi <lorenzo.pieralisi@arm•com> wrote @ Wed, 9 Jan 2013 16:17:00 +0100:
...
> With your "[PATCH] ARM: kernel: DT cpu map validity check helper
> function", my original patch gets as below. I think that the following
> "smp_detect_ncores()" function may be so generic that it could be
> moved in some common place than platform?
>
> From f5f2a43952ce75fe061b3808b994c3ceb07f1af1 Mon Sep 17 00:00:00 2001
> From: Hiroshi Doyu <hdoyu@nvidia•com>
> Date: Mon, 26 Nov 2012 12:25:14 +0200
> Subject: [PATCH 1/1] ARM: tegra: # of CPU cores detection w/ & w/o
> HAVE_ARM_SCU
>
> The method to detect the number of CPU cores on Cortex-A9 MPCore and
> Cortex-A15 MPCore is different. On Cortex-A9 MPCore we can get this
> information from the Snoop Control Unit(SCU). On Cortex-A15 MPCore we
> have to read it from the system coprocessor(CP15), because the SCU on
> Cortex-A15 MPCore does not have software readable registers. This
> patch selects the correct method at runtime based on the CPU ID.
> diff --git a/arch/arm/mach-tegra/platsmp.c b/arch/arm/mach-tegra/platsmp.c
> +static int __init smp_detect_ncores(void)
> +{
> + unsigned int ncores, mpidr;
> + u32 l2ctlr;
> + phys_addr_t pa;
> +
> + mpidr = read_cpuid_mpidr();
> + switch (mpidr) {
> + case ARM_CPU_PART_CORTEX_A15:
> + asm("mrc p15, 1, %0, c9, c0, 2\n" : "=r" (l2ctlr));
> + ncores = ((l2ctlr >> 24) & 3) + 1;
> + break;
> + case ARM_CPU_PART_CORTEX_A9:
> + /* Get SCU physical base */
> + asm("mrc p15, 4, %0, c15, c0, 0" : "=r" (pa));
> + scu_base = IO_ADDRESS(pa);
> + ncores = scu_get_core_count(scu_base);
> + break;
> + default:
> + pr_warn("Unsupported mpidr\n");
> + ncores = 1;
> + break;
> + }
> +
> + return ncores;
> +}
Why not just remove that function...
> /*
> * Initialise the CPU possible map early - this describes the CPUs
> * which may be present or become present in the system.
> */
> static void __init tegra_smp_init_cpus(void)
> {
> - unsigned int i, ncores = scu_get_core_count(scu_base);
> -
> - if (ncores > nr_cpu_ids) {
> - pr_warn("SMP: %u cores greater than maximum (%u), clipping\n",
> - ncores, nr_cpu_ids);
> - ncores = nr_cpu_ids;
> + if (!arm_dt_cpu_map_valid()) {
> + unsigned int i, ncores;
> +
> + ncores = smp_detect_ncores();
And just say "ncores = 1" here?
For Tegra, it's trivial to simply put the patch adding the required DT
nodes before this patch, and then there's no need for any
backwards-compatibility, since the nodes are guaranteed to be there.
next prev parent reply other threads:[~2013-01-10 16:54 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-08 12:47 [v2 0/9] ARM: Initial support for Tegra 114 SoC Hiroshi Doyu
2013-01-08 12:47 ` [v2 1/9] ARM: tegra: fuse: Add chipid TEGRA114 0x35 Hiroshi Doyu
2013-01-08 12:47 ` [v2 2/9] HACK: ARM: tegra: Use CLK_IGNORE_UNUSED for Tegra 114 SoC Hiroshi Doyu
2013-01-08 22:52 ` Stephen Warren
2013-01-08 12:47 ` [v2 3/9] ARM: tegra: # of CPU cores detection w/ & w/o HAVE_ARM_SCU Hiroshi Doyu
2013-01-08 14:26 ` Russell King - ARM Linux
2013-01-09 5:46 ` Hiroshi Doyu
2013-01-09 6:07 ` Joseph Lo
2013-01-09 6:25 ` Hiroshi Doyu
2013-01-08 14:28 ` Mark Rutland
2013-01-08 14:53 ` Hiroshi Doyu
2013-01-08 16:21 ` Mark Rutland
2013-01-08 17:11 ` Lorenzo Pieralisi
2013-01-09 11:46 ` Hiroshi Doyu
2013-01-09 15:17 ` Lorenzo Pieralisi
2013-01-10 12:58 ` Hiroshi Doyu
2013-01-10 13:47 ` Lorenzo Pieralisi
2013-01-10 14:03 ` Hiroshi Doyu
2013-01-10 14:33 ` Lorenzo Pieralisi
2013-01-10 14:59 ` Hiroshi Doyu
2013-01-10 16:54 ` Stephen Warren [this message]
2013-01-11 10:11 ` Lorenzo Pieralisi
2013-01-11 11:56 ` Hiroshi Doyu
2013-01-08 19:32 ` Stephen Warren
2013-01-09 5:49 ` Hiroshi Doyu
2013-01-09 11:34 ` Lorenzo Pieralisi
2013-01-09 16:17 ` Stephen Warren
2013-01-09 18:07 ` Lorenzo Pieralisi
2013-01-10 6:53 ` Hiroshi Doyu
2013-01-10 6:31 ` Hiroshi Doyu
2013-01-10 9:51 ` Lorenzo Pieralisi
2013-01-08 12:47 ` [v2 4/9] clocksource: tegra: Reorganize funcs by clock functionarities Hiroshi Doyu
2013-01-08 12:47 ` [v2 5/9] clocksource: tegra: Enable ARM arch_timer with TSC Hiroshi Doyu
2013-01-08 16:07 ` Marc Zyngier
2013-01-08 22:41 ` Stephen Warren
2013-01-09 6:00 ` Hiroshi Doyu
2013-01-09 6:40 ` Stephen Warren
2013-01-09 6:55 ` Hiroshi Doyu
2013-01-09 5:57 ` Hiroshi Doyu
2013-01-09 7:43 ` Santosh Shilimkar
2013-01-09 9:01 ` Marc Zyngier
2013-01-10 15:03 ` Hiroshi Doyu
2013-01-10 15:10 ` Marc Zyngier
2013-01-08 12:47 ` [v2 6/9] ARM: dt: tegra114: Add new SoC base, Tegra 114 SoC Hiroshi Doyu
2013-01-08 22:49 ` Stephen Warren
2013-01-10 12:35 ` Hiroshi Doyu
2013-01-08 12:47 ` [v2 7/9] ARM: dt: tegra114: Add new board, Dalmore Hiroshi Doyu
2013-01-08 12:47 ` [v2 8/9] ARM: dt: tegra114: Add new board, Pluto Hiroshi Doyu
2013-01-08 12:47 ` [v2 9/9] ARM: tegra: Add initial support for Tegra 114 SoC Hiroshi Doyu
2013-01-08 22:52 ` Stephen Warren
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