Re: [PATCH 2/2] drm/i915/bxt: Fix sanity check for BIOS RC6 setup

["Kamble, Sagar A" <sagar.a.kamble@intel.com>]

Have seen BIOS having option "RC6" disabled and "GTPM" enabled for cases 
where there are RC6 specific issues.
GTPM option entails setup for other features as well I guess.
In such cases - Can we output some DRM_INFO log saying BIOS has disabled 
RC6 although setup is available.

Do we need to also check for other unit level clock gating register 
setup done by BIOS like: GEN7_MISCCPCTL, GEN6_UCGCTL1 to GEN6_UCGCTL4, 
GEN8_UCGCTL6 etc.

Thanks
Sagar


On 6/29/2016 9:43 PM, Imre Deak wrote:
> BXT BIOS has two options related to GPU power management: "RC6(Render
> Standby)" and "GT PM Support". The assumption so far was that disabling
> either of these options would leave RC6 uninitialized. According to my
> tests this isn't so: for a proper RC6 setup we only need the "GT PM
> Support" option to be enabled while the "RC6" option only controls
> whether RC6 is left enabled or not by BIOS. OTOH we were missing a few
> checks to ensure a proper RC6 setup. Add these now and don't fail the
> sanity check if RC6 is disabled. This fixes a problem where RC6 remains
> disabled after reloading the driver, since we explicitly disable RC6
> during unloading.
>
> CC: Sagar Arun Kamble <sagar.a.kamble@intel.com>
> Signed-off-by: Imre Deak <imre.deak@intel.com>
> ---
>   drivers/gpu/drm/i915/i915_reg.h |  5 +++++
>   drivers/gpu/drm/i915/intel_pm.c | 19 ++++++++++++++-----
>   2 files changed, 19 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index c6bfbf8..92b4046 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -7085,12 +7085,17 @@ enum {
>   #define GEN6_RC6pp_THRESHOLD			_MMIO(0xA0C0)
>   #define GEN6_PMINTRMSK				_MMIO(0xA168)
>   #define   GEN8_PMINTR_REDIRECT_TO_NON_DISP	(1<<31)
> +#define GEN8_MISC_CTRL0				_MMIO(0xA180)
>   #define VLV_PWRDWNUPCTL				_MMIO(0xA294)
>   #define GEN9_MEDIA_PG_IDLE_HYSTERESIS		_MMIO(0xA0C4)
>   #define GEN9_RENDER_PG_IDLE_HYSTERESIS		_MMIO(0xA0C8)
>   #define GEN9_PG_ENABLE				_MMIO(0xA210)
>   #define GEN9_RENDER_PG_ENABLE			(1<<0)
>   #define GEN9_MEDIA_PG_ENABLE			(1<<1)
> +#define GEN8_PUSHBUS_CONTROL			_MMIO(0xA248)
> +#define GEN8_PUSHBUS_ENABLE			_MMIO(0xA250)
> +#define GEN8_PUSHBUS_SHIFT			_MMIO(0xA25C)
> +
>   
>   #define VLV_CHICKEN_3				_MMIO(VLV_DISPLAY_BASE + 0x7040C)
>   #define  PIXEL_OVERLAP_CNT_MASK			(3 << 30)
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 5dce264..fe76991 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -5015,11 +5015,20 @@ static bool bxt_check_bios_rc6_setup(struct drm_i915_private *dev_priv)
>   		enable_rc6 = false;
>   	}
>   
> -	if (!(I915_READ(GEN6_RC_CONTROL) & (GEN6_RC_CTL_RC6_ENABLE |
> -					    GEN6_RC_CTL_HW_ENABLE)) &&
> -	    ((I915_READ(GEN6_RC_CONTROL) & GEN6_RC_CTL_HW_ENABLE) ||
> -	     !(I915_READ(GEN6_RC_STATE) & RC6_STATE))) {
> -		DRM_DEBUG_DRIVER("HW/SW RC6 is not enabled by BIOS.\n");
> +	if (!I915_READ(GEN8_PUSHBUS_CONTROL) ||
> +	    !I915_READ(GEN8_PUSHBUS_ENABLE) ||
> +	    !I915_READ(GEN8_PUSHBUS_SHIFT)) {
> +		DRM_DEBUG_DRIVER("Pushbus not setup properly.\n");
> +		enable_rc6 = false;
> +	}
> +
> +	if (!I915_READ(GEN6_GFXPAUSE)) {
> +		DRM_DEBUG_DRIVER("GFX pause not setup properly.\n");
> +		enable_rc6 = false;
> +	}
> +
> +	if (!I915_READ(GEN8_MISC_CTRL0)) {
> +		DRM_DEBUG_DRIVER("GPM control not setup properly.\n");
>   		enable_rc6 = false;
>   	}
>   

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