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Date: Tue, 1 Mar 2011 14:46:56 -0500 (EST)
From: Alan Stern <stern@...land.harvard.edu>
To: Pierre Tardy <tardyp@...il.com>
cc: linux-kernel@...r.kernel.org,
<linux-pm@...ts.linux-foundation.org>, <linux-mmc@...r.kernel.org>,
Pierre Tardy <pierre.tardy@...el.com>,
Yunpeng Gao <yunpeng.gao@...el.com>
Subject: Re: [linux-pm] [RFC, PATCHv3 1/3] mmc: sdhci-pci: Enable runtime PM
support
On Tue, 1 Mar 2011, Pierre Tardy wrote:
> From: Yunpeng Gao <yunpeng.gao@...el.com>
>
> Follow the kernel runtime PM framework, enable runtime PM support of the
> sdhci host controller with pci interface.
>
> Note that this patch implements runtime_pm but now actually detects
> activity.
> It relies on higher level (childrens) to do actual waking up
> Activity detection is put in a following patch
>
> This patch also does not enable wakeups, so card insertion will not work
> if runtime_pm is activated.
> This is also dealt in a following patch
>
> Original version from: Yunpeng Gao <yunpeng.gao@...el.com>
> with modifications by: Pierre Tardy <pierre.tardy@...el.com>
>
> Signed-off-by: Pierre Tardy <pierre.tardy@...el.com>
> ---
> drivers/mmc/host/sdhci-pci.c | 120 +++++++++++++++++++++++++++++++++++++++++-
> drivers/mmc/host/sdhci.c | 31 +++++++++++
> drivers/mmc/host/sdhci.h | 5 ++
> 3 files changed, 155 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci-pci.c b/drivers/mmc/host/sdhci-pci.c
> index 2f8d468..f167a55 100644
> --- a/drivers/mmc/host/sdhci-pci.c
> +++ b/drivers/mmc/host/sdhci-pci.c
> @@ -18,6 +18,7 @@
> #include <linux/dma-mapping.h>
> #include <linux/slab.h>
> #include <linux/device.h>
> +#include <linux/pm_runtime.h>
>
> #include <linux/mmc/host.h>
>
> @@ -1031,6 +1032,8 @@ static int __devinit sdhci_pci_probe(struct pci_dev *pdev,
> if (ret)
> return ret;
>
> + pm_runtime_set_active(&pdev->dev);
This line is redundant. It won't do anything, and the PCI core already
does it.
> +
> slots = PCI_SLOT_INFO_SLOTS(slots) + 1;
> dev_dbg(&pdev->dev, "found %d slot(s)\n", slots);
> if (slots == 0)
> @@ -1086,7 +1089,7 @@ static int __devinit sdhci_pci_probe(struct pci_dev *pdev,
>
> chip->slots[i] = slot;
> }
> -
> + pm_runtime_put_noidle(&pdev->dev);
> return 0;
>
> free:
> @@ -1114,8 +1117,120 @@ static void __devexit sdhci_pci_remove(struct pci_dev *pdev)
> }
>
> pci_disable_device(pdev);
> + pm_runtime_get_noresume(&pdev->dev);
> +
> +}
> +
> +#ifdef CONFIG_PM_RUNTIME
> +
> +static int sdhci_pci_runtime_suspend(struct device *dev)
> +{
> + struct pci_dev *pdev = container_of(dev, struct pci_dev, dev);
> + struct sdhci_pci_chip *chip;
> + struct sdhci_pci_slot *slot;
> + int i, ret;
> + mmc_pm_flag_t pm_flags = 0;
> + pm_message_t state;
> +
> + chip = pci_get_drvdata(pdev);
> + if (!chip)
> + return 0;
> +
> + for (i = 0; i < chip->num_slots; i++) {
> + slot = chip->slots[i];
> + if (!slot)
> + continue;
> +
> + ret = sdhci_runtime_suspend(slot->host);
> +
> + if (ret) {
> + for (i--; i >= 0; i--)
> + sdhci_runtime_resume(chip->slots[i]->host);
> + return ret;
> + }
> +
> + pm_flags |= slot->host->mmc->pm_flags;
> + }
> +
> + state.event = PM_EVENT_AUTO_SUSPEND;
> + if (chip->fixes && chip->fixes->suspend) {
> + ret = chip->fixes->suspend(chip, state);
> + if (ret) {
> + for (i = chip->num_slots - 1; i >= 0; i--)
> + sdhci_runtime_resume(chip->slots[i]->host);
> + return ret;
> + }
> + }
You probably should call synchronize_irq() here. Otherwise a delayed
IRQ might get delivered after the device has changed to D3.
> +
> + pci_save_state(pdev);
> + if (pm_flags & MMC_PM_KEEP_POWER) {
> + if (pm_flags & MMC_PM_WAKE_SDIO_IRQ)
> + pci_enable_wake(pdev, PCI_D3hot, 1);
> + } else {
> + pci_enable_wake(pdev, PCI_D3hot, 0);
> + pci_disable_device(pdev);
> + }
> + pci_set_power_state(pdev, PCI_D3hot);
Most of this isn't needed. The PCI core does pci_save_state(),
pci_enable_wake(), and pci_set_power_state().
Of course, you might want to override the wakeup setting selected by
the core. This is determined by pci_dev_run_wake(), for which you may
need to call device_set_run_wake().
> +
> + return 0;
> }
>
> +static int sdhci_pci_runtime_resume(struct device *dev)
> +{
> + struct pci_dev *pdev = container_of(dev, struct pci_dev, dev);
> + struct sdhci_pci_chip *chip;
> + struct sdhci_pci_slot *slot;
> + int i, ret;
> +
> + chip = pci_get_drvdata(pdev);
> + if (!chip)
> + return 0;
> +
> + pci_set_power_state(pdev, PCI_D0);
> + pci_restore_state(pdev);
The PCI core does pci_set_power_state() and pci_restore_state().
> + ret = pci_enable_device(pdev);
> + if (ret)
> + return ret;
> +
> + if (chip->fixes && chip->fixes->resume) {
> + ret = chip->fixes->resume(chip);
> + if (ret)
> + return ret;
> + }
> +
> + for (i = 0; i < chip->num_slots; i++) {
> + slot = chip->slots[i];
> + if (!slot)
> + continue;
> +
> + ret = sdhci_runtime_resume(slot->host);
> + if (ret)
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> +static int sdhci_pci_runtime_idle(struct device *dev)
> +{
> + pm_runtime_autosuspend(dev);
> + return -EAGAIN;
> +}
Alan Stern
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