[Intel-gfx] [PATCH v2 2/2] drm/i915: access the PP_ON_DELAYS/PP_OFF_DELAYS regs only pre GEN5

[Jani Nikula]

On Thu, 03 Sep 2015, Imre Deak <imre.deak at intel.com> wrote:
> These registers exist only before GEN5, so currently we may access
> undefined registers on VLV/CHV and BXT. Apply the workaround only pre
> GEN5.
>
> Since the workaround is relevant only when LVDS is present, for clarity
> apply it only if this is the case.

Fun thought, if those registers are indeed 0, it's probably safe to
assume PP_CONTROL is too, or at least doesn't have PANEL_UNLOCK_REGS
set... which in turn would mean the write in intel_setup_bios() didn't
go through anyway. With this patch, we'll actually do something about
it. :)

Jani.



>
> This triggered an unclaimed register access warning on BXT.
>
> v2: (Ville)
> - move the workaround to the LVDS init code
> - print a debug note about the workaround
>
> Signed-off-by: Imre Deak <imre.deak at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_dma.c   |  2 --
>  drivers/gpu/drm/i915/intel_bios.c | 18 ------------------
>  drivers/gpu/drm/i915/intel_bios.h |  1 -
>  drivers/gpu/drm/i915/intel_lvds.c | 12 ++++++++++++
>  4 files changed, 12 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> index f0eaa6f..066a0ef 100644
> --- a/drivers/gpu/drm/i915/i915_dma.c
> +++ b/drivers/gpu/drm/i915/i915_dma.c
> @@ -997,8 +997,6 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
>  	intel_setup_gmbus(dev);
>  	intel_opregion_setup(dev);
>  
> -	intel_setup_bios(dev);
> -
>  	i915_gem_load(dev);
>  
>  	/* On the 945G/GM, the chipset reports the MSI capability on the
> diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
> index b3e437b..c8acc29 100644
> --- a/drivers/gpu/drm/i915/intel_bios.c
> +++ b/drivers/gpu/drm/i915/intel_bios.c
> @@ -1340,21 +1340,3 @@ intel_parse_bios(struct drm_device *dev)
>  
>  	return 0;
>  }
> -
> -/* Ensure that vital registers have been initialised, even if the BIOS
> - * is absent or just failing to do its job.
> - */
> -void intel_setup_bios(struct drm_device *dev)
> -{
> -	struct drm_i915_private *dev_priv = dev->dev_private;
> -
> -	 /* Set the Panel Power On/Off timings if uninitialized. */
> -	if (!HAS_PCH_SPLIT(dev) &&
> -	    I915_READ(PP_ON_DELAYS) == 0 && I915_READ(PP_OFF_DELAYS) == 0) {
> -		/* Set T2 to 40ms and T5 to 200ms */
> -		I915_WRITE(PP_ON_DELAYS, 0x019007d0);
> -
> -		/* Set T3 to 35ms and Tx to 200ms */
> -		I915_WRITE(PP_OFF_DELAYS, 0x015e07d0);
> -	}
> -}
> diff --git a/drivers/gpu/drm/i915/intel_bios.h b/drivers/gpu/drm/i915/intel_bios.h
> index 46cd5c7..1b7417e 100644
> --- a/drivers/gpu/drm/i915/intel_bios.h
> +++ b/drivers/gpu/drm/i915/intel_bios.h
> @@ -588,7 +588,6 @@ struct bdb_psr {
>  	struct psr_table psr_table[16];
>  } __packed;
>  
> -void intel_setup_bios(struct drm_device *dev);
>  int intel_parse_bios(struct drm_device *dev);
>  
>  /*
> diff --git a/drivers/gpu/drm/i915/intel_lvds.c b/drivers/gpu/drm/i915/intel_lvds.c
> index a16308a..2c2d1f0 100644
> --- a/drivers/gpu/drm/i915/intel_lvds.c
> +++ b/drivers/gpu/drm/i915/intel_lvds.c
> @@ -985,6 +985,18 @@ void intel_lvds_init(struct drm_device *dev)
>  		DRM_DEBUG_KMS("LVDS is not present in VBT, but enabled anyway\n");
>  	}
>  
> +	 /* Set the Panel Power On/Off timings if uninitialized. */
> +	if (INTEL_INFO(dev_priv)->gen < 5 &&
> +	    I915_READ(PP_ON_DELAYS) == 0 && I915_READ(PP_OFF_DELAYS) == 0) {
> +		/* Set T2 to 40ms and T5 to 200ms */
> +		I915_WRITE(PP_ON_DELAYS, 0x019007d0);
> +
> +		/* Set T3 to 35ms and Tx to 200ms */
> +		I915_WRITE(PP_OFF_DELAYS, 0x015e07d0);
> +
> +		DRM_DEBUG_KMS("Panel power timings uninitialized, setting defaults\n");
> +	}
> +
>  	lvds_encoder = kzalloc(sizeof(*lvds_encoder), GFP_KERNEL);
>  	if (!lvds_encoder)
>  		return;
> -- 
> 2.1.4
>
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-- 
Jani Nikula, Intel Open Source Technology Center