Re: [PATCH 05/19] drm/i915: add initial Runtime PM functions

Takashi Iwai
2013-11-29T14:05:55Z

At Wed, 27 Nov 2013 18:10:30 -0200,
Paulo Zanoni wrote:
>
> From: Paulo Zanoni <paulo.r.zanoni@intel.com>
>
> This patch adds the initial infrastructure to allow a Runtime PM
> implementation that sets the device to its D3 state. The patch just
> adds the necessary callbacks and the initial infrastructure.
>
> We still don't have any platform that actually uses this
> infrastructure, we still don't call get/put in all the places we need
> to, and we don't have any function to save/restore the state of the
> registers. This is not a problem since no platform uses the code added
> by this patch. We have a few people simultaneously working on runtime
> PM, so this initial code could help everybody make their plans.
>
> V2: - Move some functions to intel_pm.c
> - Remove useless pm_runtime_allow() call at init
> - Remove useless pm_runtime_mark_last_busy() call at get
> - Use pm_runtime_get_sync() instead of 2 calls
> - Add a WARN to check if we're really awake
>
> V3: - Rebase.
>
> Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
> ---
> drivers/gpu/drm/i915/i915_dma.c | 6 ++++
> drivers/gpu/drm/i915/i915_drv.c | 42 ++++++++++++++++++++++++++++
> drivers/gpu/drm/i915/i915_drv.h | 7 +++++
> drivers/gpu/drm/i915/intel_drv.h | 4 +++
> drivers/gpu/drm/i915/intel_pm.c | 56 +++++++++++++++++++++++++++++++++++++
> drivers/gpu/drm/i915/intel_uncore.c | 9 ++++++
> 6 files changed, 124 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> index 89e4cf1..4cdc1ee 100644
> --- a/drivers/gpu/drm/i915/i915_dma.c
> +++ b/drivers/gpu/drm/i915/i915_dma.c
> @@ -42,6 +42,8 @@
> #include <linux/vga_switcheroo.h>
> #include <linux/slab.h>
> #include <acpi/video.h>
> +#include <linux/pm.h>
> +#include <linux/pm_runtime.h>
>
> #define LP_RING(d) (&((struct drm_i915_private *)(d))->ring[RCS])
>
> @@ -1663,6 +1665,8 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
> if (IS_GEN5(dev))
> intel_gpu_ips_init(dev_priv);
>
> + intel_init_runtime_pm(dev_priv);
> +
> return 0;
>
> out_power_well:
> @@ -1702,6 +1706,8 @@ int i915_driver_unload(struct drm_device *dev)
> struct drm_i915_private *dev_priv = dev->dev_private;
> int ret;
>
> + intel_fini_runtime_pm(dev_priv);
> +
> intel_gpu_ips_teardown();
>
> /* The i915.ko module is still not prepared to be loaded when
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index 0ec0fb3..d5310a0 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -502,6 +502,8 @@ static int i915_drm_freeze(struct drm_device *dev)
> struct drm_i915_private *dev_priv = dev->dev_private;
> struct drm_crtc *crtc;
>
> + intel_runtime_pm_get(dev_priv);
> +
> /* ignore lid events during suspend */
> mutex_lock(&dev_priv->modeset_restore_lock);
> dev_priv->modeset_restore = MODESET_SUSPENDED;
> @@ -688,6 +690,8 @@ static int __i915_drm_thaw(struct drm_device *dev, bool restore_gtt_mappings)
> mutex_lock(&dev_priv->modeset_restore_lock);
> dev_priv->modeset_restore = MODESET_DONE;
> mutex_unlock(&dev_priv->modeset_restore_lock);
> +
> + intel_runtime_pm_put(dev_priv);
> return error;
> }
>
> @@ -902,6 +906,42 @@ static int i915_pm_poweroff(struct device *dev)
> return i915_drm_freeze(drm_dev);
> }
>
> +static int i915_runtime_suspend(struct device *device)
> +{
> + struct pci_dev *pdev = to_pci_dev(device);
> + struct drm_device *dev = pci_get_drvdata(pdev);
> + struct drm_i915_private *dev_priv = dev->dev_private;
> +
> + WARN_ON(!HAS_RUNTIME_PM(dev));

It'd be better to add runtime_idle callback for this kind of checks.
It's called always before actually doing runtime PM, and you can
return -EBUSY if the runtime PM isn't available.

> + DRM_DEBUG_KMS("Suspending device\n");
> +
> + dev_priv->pm.suspended = true;
> +
> + pci_save_state(pdev);
> + pci_set_power_state(pdev, PCI_D3cold);

Why do you need these calls? PCI runtime PM core should already
handle the power state change by itself.

Takashi