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Date: Mon, 20 Oct 2008 10:32:14 -0700
From: Randy Dunlap <randy.dunlap@...cle.com>
To: Len Brown <lenb@...nel.org>
Cc: Ingo Molnar <mingo@...e.hu>, linux-acpi@...r.kernel.org,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Venki Pallipadi <venkatesh.pallipadi@...el.com>,
Andy Henroid <andrew.d.henroid@...el.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Thomas Gleixner <tglx@...utronix.de>,
"H. Peter Anvin" <hpa@...or.com>, Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH 2/2] i7300_idle driver v1.55
On Thu, 16 Oct 2008 18:08:01 -0400 (EDT) Len Brown wrote:
> From: Andy Henroid <andrew.d.henroid@...el.com>
>
> The Intel 7300 Memory Controller supports dynamic throttling of memory which can
> be used to save power when system is idle. This driver does the memory
> throttling when all CPUs are idle on such a system.
>
> Refer to "Intel 7300 Memory Controller Hub (MCH)" datasheet
> for the config space description.
>
> Signed-off-by: Andy Henroid <andrew.d.henroid@...el.com>
> Signed-off-by: Len Brown <len.brown@...el.com>
> Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>
> ---
> MAINTAINERS | 6 +
> arch/x86/Kconfig | 2 +
> drivers/Makefile | 1 +
> drivers/dma/ioat_dma.c | 3 +
> drivers/idle/Kconfig | 16 +
> drivers/idle/Makefile | 2 +
> drivers/idle/i7300_idle.c | 674 +++++++++++++++++++++++++++++++++++++++++++++
Why not just use drivers/power/ instead of a new sub-directory?
> include/asm-x86/idle.h | 1 +
> include/linux/pci_ids.h | 1 +
> 9 files changed, 706 insertions(+), 0 deletions(-)
> create mode 100644 drivers/idle/Kconfig
> create mode 100644 drivers/idle/Makefile
> create mode 100644 drivers/idle/i7300_idle.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 8dae455..43f71b0 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -2078,6 +2078,12 @@ L: linux-ide@...r.kernel.org
> L: linux-scsi@...r.kernel.org
> S: Orphan
>
> +IDLE-I7300
> +P: Andy Henroid
> +M: andrew.d.henroid@...el.com
welcome back.
> +L: linux-pm@...ts.linux-foundation.org
> +S: Supported
> +
> IEEE 1394 SUBSYSTEM (drivers/ieee1394)
> P: Ben Collins
> M: ben.collins@...ntu.com
> diff --git a/drivers/idle/i7300_idle.c b/drivers/idle/i7300_idle.c
> new file mode 100644
> index 0000000..59d1bbc
> --- /dev/null
> +++ b/drivers/idle/i7300_idle.c
> @@ -0,0 +1,674 @@
> +/*
> + * (C) Copyright 2008 Intel Corporation
> + * Authors:
> + * Andy Henroid <andrew.d.henroid@...el.com>
> + * Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>
> + */
> +
> +
> +/*
> + * Value to set THRTLOW to when initiating throttling
> + * 0 = No throttling
> + * 1 = Throttle when > 4 activations per eval window (Maximum throttling)
> + * 2 = Throttle when > 8 activations
> + * 168 = Throttle when > 168 activations (Minimum throttling)
Why do some numbers mean > their value (i.e., 168) but others don't?
Is it a linear value or logarithmic or what?
> + */
> +#define MAX_THRTLWLIMIT 168
> +static uint i7300_idle_thrtlowlm = 1;
> +module_param_named(thrtlwlimit, i7300_idle_thrtlowlm, uint, 0644);
> +MODULE_PARM_DESC(thrtlwlimit,
> + "Value for THRTLOWLM activation field "
> + "(0 = disable throttle, 1 = Max throttle, 168 = Min throttle)");
> +
> +/* Stop I/O AT memory copy */
> +static void i7300_idle_ioat_stop(void)
> +{
> + int i;
> + u8 sts;
> +
> + for (i = 0; i < 5; i++) {
> + writeb(IOAT_CHANCMD_RESET,
> + ioat_chanbase + IOAT1_CHANCMD_OFFSET);
> +
> + udelay(10);
> +
> + sts = readq(ioat_chanbase + IOAT1_CHANSTS_OFFSET) &
> + IOAT_CHANSTS_DMA_TRANSFER_STATUS;
readq() returns 64 bits. You only want to LS-byte of it here?
> + if (sts != IOAT_CHANSTS_DMA_TRANSFER_STATUS_ACTIVE)
> + break;
> +
> + }
> +
> + if (i == 5)
> + dprintk("failed to suspend+reset I/O AT after 5 retries\n");
> +
> +}
> +struct debugfs_file_info {
> + void *ptr;
> + char name[32];
> + struct dentry *file;
> +} debugfs_file_list[] = {
> + {&total_starts, "total_starts", NULL},
> + {&total_us, "total_us", NULL},
> +#ifdef DEBUG
> + {&past_skip, "past_skip", NULL},
> +#endif
> + {NULL, "", NULL}
> + };
What is debugfs used for? any docs for it?
Does this build/work if CONFIG_DEBUG_FS=n?
> +static int __init i7300_idle_init(void)
> +{
> + spin_lock_init(&i7300_idle_lock);
> + cpus_clear(idle_cpumask);
> + total_us = 0;
> +
> + if (i7300_idle_platform_probe())
> + return -ENODEV;
> +
> + if (i7300_idle_thrt_save())
> + return -ENODEV;
> +
> + if (i7300_idle_ioat_init())
> + return -ENODEV;
> +
> + debugfs_dir = debugfs_create_dir("i7300_idle", NULL);
> + if (debugfs_dir) {
> + int i = 0;
> +
> + while (debugfs_file_list[i].ptr != NULL) {
> + debugfs_file_list[i].file = debugfs_create_file(
> + debugfs_file_list[i].name,
> + S_IRUSR,
> + debugfs_dir,
> + debugfs_file_list[i].ptr,
> + &idle_fops);
> + i++;
> + }
> + }
> +
> + idle_notifier_register(&i7300_idle_nb);
> +
> + printk(KERN_INFO "i7300_idle: loaded v%s\n", I7300_IDLE_DRIVER_VERSION);
> + return 0;
> +}
---
~Randy
--
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