Re: [PATCH 14/19] drm/i915: add runtime PM support on Haswell

[Daniel Vetter <daniel@ffwll.ch>]

On Thu, Nov 21, 2013 at 01:47:28PM -0200, Paulo Zanoni wrote:
> From: Paulo Zanoni <paulo.r.zanoni@intel.com>
> 
> The code to enable/disable PC8 already takes care of saving and
> restoring all the registers we need to save/restore, so do a put()
> call when we enable PC8 and a get() call when we disable it.
> 
> Ideally, in order to make it easier to add runtime PM support to other
> platforms, we should move some things from the PC8 code to the runtime
> PM code, but let's do this later, since we can make Haswell work right
> now.

Nah, I think this is the right approach. Each power domain should only
grab references to the next outer one. So on hsw we'd have

power well -> pc8 -> runtime D3

On other platfroms maybe

power well A -+-> runtime D3
power well B -|

Hence why I think that we need to shovel the hsw pc8 reference get/put
into the display power wells - we have an always-on power well so this
should fit nicely.

Anyway, current patch merged.
-Daniel

> 
> V2: - Rebase
> 
> Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.h      | 2 +-
>  drivers/gpu/drm/i915/intel_display.c | 4 ++++
>  2 files changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 3702746..002b99d 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1836,7 +1836,7 @@ struct drm_i915_file_private {
>  #define HAS_FPGA_DBG_UNCLAIMED(dev)	(INTEL_INFO(dev)->has_fpga_dbg)
>  #define HAS_PSR(dev)		(IS_HASWELL(dev) || IS_BROADWELL(dev))
>  #define HAS_PC8(dev)		(IS_HASWELL(dev)) /* XXX HSW:ULX */
> -#define HAS_RUNTIME_PM(dev)	false
> +#define HAS_RUNTIME_PM(dev)	(IS_HASWELL(dev))
>  
>  #define INTEL_PCH_DEVICE_ID_MASK		0xff00
>  #define INTEL_PCH_IBX_DEVICE_ID_TYPE		0x3b00
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 95e8831..820013a 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -6641,6 +6641,8 @@ void hsw_enable_pc8_work(struct work_struct *__work)
>  	lpt_disable_clkout_dp(dev);
>  	hsw_pc8_disable_interrupts(dev);
>  	hsw_disable_lcpll(dev_priv, true, true);
> +
> +	intel_runtime_pm_put(dev_priv);
>  }
>  
>  static void __hsw_enable_package_c8(struct drm_i915_private *dev_priv)
> @@ -6678,6 +6680,8 @@ static void __hsw_disable_package_c8(struct drm_i915_private *dev_priv)
>  
>  	DRM_DEBUG_KMS("Disabling package C8+\n");
>  
> +	intel_runtime_pm_get(dev_priv);
> +
>  	hsw_restore_lcpll(dev_priv);
>  	hsw_pc8_restore_interrupts(dev);
>  	lpt_init_pch_refclk(dev);
> -- 
> 1.8.3.1
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch