lkml.org 
[lkml]   [2011]   [Nov]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH/RESEND #3 1/7] OMAP3+: PM: SR: add suspend/resume handlers
    Date
    From: Nishanth Menon <nm@ti.com>

    SmartReflex should be disabled while entering low power mode due to
    the following reasons:
    a) SmartReflex values are not defined for retention voltage.
    b) With SmartReflex enabled, if the CPU enters low power state, FSM
    will try to bump the voltage to current OPP's voltage for which
    it has entered low power state, causing power loss and potential
    unknown states for the SoC.
    Since we are sure to attempt entering the lowest possible power state
    during suspend operation, SmartReflex needs to be disabled for the
    voltage domains in suspend path before achieving auto retention voltage
    on the device.

    Traditionally, this has been done with interrupts disabled as part of
    the common code which handles the idle sequence. Instead, by using the
    fact that we have to disable SmartReflex for sure during suspend
    operations, we can opportunistically disable SmartReflex in device
    standard pm ops, instead of disabling it as part of the code which
    executes with interrupts disabled and slave CPU{s} shutdown. This
    allows the system to do other parallel activities(such as suspending
    other devices in the system using slave CPU{s}) and save the time
    required to achieve suspend and resume from suspended state as a
    sequential activity.

    However, by being opportunistic as described above, we also increase
    the likelihood of SmartReflex library access functions being invoked in
    parallel contexts *after* SmartReflex driver's suspend handler (during
    suspend operation) or *before* resume handler (during resume operation)
    have been invoked (Example: DVFS for dependent devices, cpufreq for
    MPU etc.). We prevent this by using a flag to reject the callers in
    the duration where SmartReflex has been disabled.

    Signed-off-by: Nishanth Menon <nm@ti.com>
    ---
    arch/arm/mach-omap2/smartreflex.c | 96 ++++++++++++++++++++++++++++++++++--
    1 files changed, 90 insertions(+), 6 deletions(-)

    diff --git a/arch/arm/mach-omap2/smartreflex.c b/arch/arm/mach-omap2/smartreflex.c
    index 6a4f683..5763a71 100644
    --- a/arch/arm/mach-omap2/smartreflex.c
    +++ b/arch/arm/mach-omap2/smartreflex.c
    @@ -24,6 +24,7 @@
    #include <linux/debugfs.h>
    #include <linux/delay.h>
    #include <linux/slab.h>
    +#include <linux/pm.h>
    #include <linux/pm_runtime.h>

    #include <plat/common.h>
    @@ -40,6 +41,7 @@ struct omap_sr {
    int ip_type;
    int nvalue_count;
    bool autocomp_active;
    + bool is_suspended;
    u32 clk_length;
    u32 err_weight;
    u32 err_minlimit;
    @@ -685,6 +687,11 @@ void omap_sr_enable(struct voltagedomain *voltdm)
    if (!sr->autocomp_active)
    return;

    + if (sr->is_suspended) {
    + dev_dbg(&sr->pdev->dev, "%s: in suspended state\n", __func__);
    + return;
    + }
    +
    if (!sr_class || !(sr_class->enable) || !(sr_class->configure)) {
    dev_warn(&sr->pdev->dev, "%s: smartreflex class driver not"
    "registered\n", __func__);
    @@ -718,6 +725,11 @@ void omap_sr_disable(struct voltagedomain *voltdm)
    if (!sr->autocomp_active)
    return;

    + if (sr->is_suspended) {
    + dev_dbg(&sr->pdev->dev, "%s: in suspended state\n", __func__);
    + return;
    + }
    +
    if (!sr_class || !(sr_class->disable)) {
    dev_warn(&sr->pdev->dev, "%s: smartreflex class driver not"
    "registered\n", __func__);
    @@ -751,6 +763,11 @@ void omap_sr_disable_reset_volt(struct voltagedomain *voltdm)
    if (!sr->autocomp_active)
    return;

    + if (sr->is_suspended) {
    + dev_dbg(&sr->pdev->dev, "%s: in suspended state\n", __func__);
    + return;
    + }
    +
    if (!sr_class || !(sr_class->disable)) {
    dev_warn(&sr->pdev->dev, "%s: smartreflex class driver not"
    "registered\n", __func__);
    @@ -809,14 +826,16 @@ static int omap_sr_autocomp_store(void *data, u64 val)
    return -EINVAL;
    }

    - /* control enable/disable only if there is a delta in value */
    - if (sr_info->autocomp_active != val) {
    - if (!val)
    - sr_stop_vddautocomp(sr_info);
    - else
    - sr_start_vddautocomp(sr_info);
    + if (sr_info->is_suspended) {
    + pr_warning("%s: in suspended state\n", __func__);
    + return -EBUSY;
    }

    + if (!val)
    + sr_stop_vddautocomp(sr_info);
    + else
    + sr_start_vddautocomp(sr_info);
    +
    return 0;
    }

    @@ -1011,10 +1030,75 @@ static int __devexit omap_sr_remove(struct platform_device *pdev)
    return 0;
    }

    +static int omap_sr_suspend(struct device *dev)
    +{
    + struct omap_sr_data *pdata;
    + struct omap_sr *sr_info;
    +
    + pdata = dev_get_platdata(dev);
    + if (!pdata) {
    + dev_err(dev, "%s: platform data missing\n", __func__);
    + return -EINVAL;
    + }
    +
    + sr_info = _sr_lookup(pdata->voltdm);
    + if (IS_ERR(sr_info)) {
    + dev_warn(dev, "%s: omap_sr struct not found\n", __func__);
    + return -EINVAL;
    + }
    +
    + if (!sr_info->autocomp_active)
    + return 0;
    +
    + if (sr_info->is_suspended)
    + return 0;
    +
    + omap_sr_disable_reset_volt(pdata->voltdm);
    + sr_info->is_suspended = true;
    + /* Flag the same info to the other CPUs */
    + smp_wmb();
    +
    + return 0;
    +}
    +
    +static int omap_sr_resume(struct device *dev)
    +{
    + struct omap_sr_data *pdata;
    + struct omap_sr *sr_info;
    +
    + pdata = dev_get_platdata(dev);
    + if (!pdata) {
    + dev_err(dev, "%s: platform data missing\n", __func__);
    + return -EINVAL;
    + }
    +
    + sr_info = _sr_lookup(pdata->voltdm);
    + if (IS_ERR(sr_info)) {
    + dev_warn(dev, "%s: omap_sr struct not found\n", __func__);
    + return -EINVAL;
    + }
    +
    + if (!sr_info->autocomp_active)
    + return 0;
    +
    + if (!sr_info->is_suspended)
    + return 0;
    +
    + sr_info->is_suspended = false;
    + /* Flag the same info to the other CPUs */
    + smp_wmb();
    + omap_sr_enable(pdata->voltdm);
    +
    + return 0;
    +}
    +
    +static SIMPLE_DEV_PM_OPS(omap_sr_dev_pm_ops, omap_sr_suspend, omap_sr_resume);
    +
    static struct platform_driver smartreflex_driver = {
    .remove = omap_sr_remove,
    .driver = {
    .name = "smartreflex",
    + .pm = &omap_sr_dev_pm_ops,
    },
    };

    --
    1.7.8.rc0


    \
     
     \ /
      Last update: 2011-11-15 09:49    [W:4.019 / U:0.048 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site