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    SubjectRe: [PATCHv5 4/4] ARM: mx51: Add support for low power suspend on MX51
    On Mon, Mar 21, 2011 at 04:30:38PM -0500, Dinh.Nguyen@freescale.com wrote:
    > From: Dinh Nguyen <Dinh.Nguyen@freescale.com>
    >
    > Adds initial low power suspend functionality to MX51.
    > Supports "mem" and "standby" modes.
    >
    > Tested on mx51-babbage.
    >
    > Signed-off-by: Dinh Nguyen <Dinh.Nguyen@freescale.com>
    > ---
    > arch/arm/mach-mx5/Makefile | 1 +
    > arch/arm/mach-mx5/pm-imx51.c | 74 ++++++++++++++++++++++++++++++++++++++++++
    > 2 files changed, 75 insertions(+), 0 deletions(-)
    > create mode 100644 arch/arm/mach-mx5/pm-imx51.c
    >
    > diff --git a/arch/arm/mach-mx5/Makefile b/arch/arm/mach-mx5/Makefile
    > index 0b9338c..787cb80 100644
    > --- a/arch/arm/mach-mx5/Makefile
    > +++ b/arch/arm/mach-mx5/Makefile
    > @@ -6,6 +6,7 @@
    > obj-y := cpu.o mm.o clock-mx51-mx53.o devices.o ehci.o system.o
    > obj-$(CONFIG_SOC_IMX50) += mm-mx50.o
    >
    > +obj-$(CONFIG_PM) += pm-imx51.o
    > obj-$(CONFIG_CPU_FREQ_IMX) += cpu_op-mx51.o
    > obj-$(CONFIG_MACH_MX51_BABBAGE) += board-mx51_babbage.o
    > obj-$(CONFIG_MACH_MX51_3DS) += board-mx51_3ds.o
    > diff --git a/arch/arm/mach-mx5/pm-imx51.c b/arch/arm/mach-mx5/pm-imx51.c
    > new file mode 100644
    > index 0000000..f5164b2
    > --- /dev/null
    > +++ b/arch/arm/mach-mx5/pm-imx51.c
    > @@ -0,0 +1,74 @@
    > +/*
    > + * Copyright (C) 2011 Freescale Semiconductor, Inc. All Rights Reserved.
    > + *
    > + * The code contained herein is licensed under the GNU General Public
    > + * License. You may obtain a copy of the GNU General Public License
    > + * Version 2 or later at the following locations:
    > + *
    > + * http://www.opensource.org/licenses/gpl-license.html
    > + * http://www.gnu.org/copyleft/gpl.html
    > + */
    > +#include <linux/suspend.h>
    > +#include <linux/clk.h>
    > +#include <linux/io.h>
    > +#include <asm/cacheflush.h>
    > +#include <asm/tlbflush.h>
    > +#include <mach/system.h>
    > +#include "crm_regs.h"
    > +
    > +static struct clk *gpc_dvfs_clk;
    > +
    > +static int mx5_suspend_enter(suspend_state_t state)

    Either the name of the file or the name of this function is wrong. You
    should decide for imx5 or imx51.

    > +{
    > + if (gpc_dvfs_clk == NULL)
    > + gpc_dvfs_clk = clk_get(NULL, "gpc_dvfs");
    > +
    > + if (gpc_dvfs_clk) {
    > + clk_enable(gpc_dvfs_clk);
    > + switch (state) {
    > + case PM_SUSPEND_MEM:
    > + mx5_cpu_lp_set(STOP_POWER_OFF);
    > + break;
    > + case PM_SUSPEND_STANDBY:
    > + mx5_cpu_lp_set(WAIT_UNCLOCKED_POWER_OFF);
    > + break;
    > + default:
    > + return -EINVAL;
    > + }
    > +
    > + if (state == PM_SUSPEND_MEM) {
    > + local_flush_tlb_all();
    > + flush_cache_all();
    > +
    > + /*clear the EMPGC0/1 bits */
    > + __raw_writel(0, MXC_SRPG_EMPGC0_SRPGCR);
    > + __raw_writel(0, MXC_SRPG_EMPGC1_SRPGCR);
    > + }
    > + cpu_do_idle();
    > + clk_disable(gpc_dvfs_clk);
    > + }else {
    > + printk(KERN_ERR "Cannot enter SRPG suspend -no gpc_dvfs clock!\n");
    > + return -EPERM;
    > + }
    > +
    > + return 0;
    > +}
    > +
    > +static int mx5_pm_valid(suspend_state_t state)
    > +{
    > + return (state > PM_SUSPEND_ON && state <= PM_SUSPEND_MAX);
    > +}
    > +
    > +static const struct platform_suspend_ops mx5_suspend_ops = {
    > + .valid = mx5_pm_valid,
    > + .enter = mx5_suspend_enter,
    > +};
    > +
    > +static int __init mx5_pm_init(void)
    > +{

    You should call clk_get here. Then you don't have to do the test for the
    clock over and over again and can print the warning only once. Also, NULL
    can be a valid clock. Please use IS_ERR().

    Sascha

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