[Intel-gfx] [PATCH v4 0/5] HPD support during suspend for BXT/APL.

[David Weinehall]

On Mon, Jun 12, 2017 at 08:54:02PM +0530, Animesh Manna wrote:
> Along with below patches sharing some background details/design.
> - On BXT, Display cannot generate an interrupt when in D3.
> - Without display in D3, S0ix can be achieved, Power impact will be zero if d3 is blocked. PMCSR for Graphics/Display is irrelevant, as the power management for them is taken care by the PUNIT using RC6/DC9 hints and *not* through PMCSR write trigger.

Does this apply to GLK as well?

> 
> So solution is based on below principles:
> - Display should not be put into D3 for HPD to work.
> - With D0+DC9 we can achieve S0ix and at the same time helps to get the interrupt.
> - Using pci_save_state() during suspend to take control from OSPM and blocking D3, while resuming, giving back to OSPM by pci_restore_state(). 
> - _DSM method is used to program pmc hpd control register to enable hpd during suspend.
> 
> Please have a look and send your comments/suggestions.
> 
> v1: Initial version sent as RFC.
> 
> v2: Updated version after addressing review comments from Imre,David.
> 
> v3: Updated version after addressing review commnets from Imre, Ville,
>     Chris.
> 
> v4: New version updated after bios changes on APL platform.
> 
> Animesh Manna (5):
>   drm/i915/bxt: Corrected the guid for bxt.
>   drm/i915/bxt: VBT changes for hpd as wakeup feature
>   drm/i915/bxt: Added _DSM call to set HPD_CTL.
>   drm/i915/bxt: Block D3 during suspend.
>   drm/i915: Enable HPD interrupts with master ctl interrupt
> 
>  drivers/gpu/drm/i915/i915_drv.c         |  5 +++
>  drivers/gpu/drm/i915/i915_drv.h         |  3 ++
>  drivers/gpu/drm/i915/i915_irq.c         | 69 +++++++++++++++++++++++++++++++--
>  drivers/gpu/drm/i915/i915_reg.h         |  8 ++++
>  drivers/gpu/drm/i915/intel_acpi.c       | 59 ++++++++++++++++++++++++----
>  drivers/gpu/drm/i915/intel_bios.c       |  4 ++
>  drivers/gpu/drm/i915/intel_runtime_pm.c |  3 +-
>  drivers/gpu/drm/i915/intel_vbt_defs.h   |  3 +-
>  8 files changed, 141 insertions(+), 13 deletions(-)
> 
> -- 
> 1.9.1
> 
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