On Fri, Oct 30, 2015 at 05:00:49PM +0530, Sagar Arun Kamble wrote:
> RC6 setup is shared between BIOS and Driver. BIOS sets up subset of RC6
> configuration registers. If those are not setup Driver should not enable RC6.
> For implementing this, driver can check RC_CTRL0 and RC_CTRL1 values
> to know if BIOS has enabled HW/SW RC6.
> This will also enable user to control RC6 using BIOS settings alone.
>
> v2: Had placed logic in gen8 function by mistake. Fixed it. Ensuring RPM is
> not enabled in case BIOS disabled RC6.
>
> Change-Id: If89518708e133be6b3c7c6f90869fb66224b7b87
> Signed-off-by: Sagar Arun Kamble <sagar.a.kamble@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/intel_pm.c | 15 +++++++++++++++
> 1 file changed, 15 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 2c7c9fc..1ec52f2 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -30,6 +30,7 @@
> #include "intel_drv.h"
> #include "../../../platform/x86/intel_ips.h"
> #include <linux/module.h>
> +#include <linux/pm_runtime.h>
>
> /**
> * RC6 is a special power stage which allows the GPU to enter an very
> @@ -4763,6 +4764,20 @@ static void gen9_enable_rc6(struct drm_device *dev)
> struct intel_engine_cs *ring;
> uint32_t rc6_mask = 0;
> int unused;
> + bool hw_rc6_enabled, sw_rc6_enabled;
> + struct device *device = &dev->pdev->dev;
> +
> + /* Check if BIOS has enabled HW/SW RC6. Only then enable RC6 */
> + hw_rc6_enabled = I915_READ(GEN6_RC_CONTROL) &
> + (GEN6_RC_CTL_RC6_ENABLE | GEN6_RC_CTL_HW_ENABLE);
> + sw_rc6_enabled = !(I915_READ(GEN6_RC_CONTROL) & GEN6_RC_CTL_HW_ENABLE)
> + && (I915_READ(GEN6_RC_STATE) & 0x40000);
Please add a define for the magic value 0x40000. Also, should we check
this on earlier platforms too? In that case a small helper and calling it
everywhere would be great.
-Daniel
> + if (!(hw_rc6_enabled || sw_rc6_enabled)) {
> + i915.enable_rc6 = 0;
> + pm_runtime_forbid(device);
> + DRM_INFO("RC6 disabled by BIOS, disabled runtime PM support\n");
> + }
> +
>
> /* 1a: Software RC state - RC0 */
> I915_WRITE(GEN6_RC_STATE, 0);
> --
> 1.9.1
>
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--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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