[Intel-gfx] [PATCH 1/6] drm/i915: Adding VBT fields to support eDP DRRS feature

[Jani Nikula]

On Fri, 07 Mar 2014, Vandana Kannan <vandana.kannan at intel.com> wrote:
> From: Pradeep Bhat <pradeep.bhat at intel.com>
>
> This patch reads the DRRS support and Mode type from VBT fields.
> The read information will be stored in VBT struct during BIOS
> parsing. The above functionality is needed for decision making
> whether DRRS feature is supported in i915 driver for eDP panels.
> This information helps us decide if seamless DRRS can be done
> at runtime to support certain power saving features. This patch
> was tested by setting necessary bit in VBT struct and merging
> the new VBT with system BIOS so that we can read the value.
>
> v2: Incorporated review comments from Chris Wilson
> Removed "intel_" as a prefix for DRRS specific declarations.
>
> v3: Incorporated Jani's review comments
> Removed function which deducts drrs mode from panel_type. Modified some
> print statements. Made changes to use DRRS_NOT_SUPPORTED as 0 instead of -1.
>
> Signed-off-by: Pradeep Bhat <pradeep.bhat at intel.com>
> Signed-off-by: Vandana Kannan <vandana.kannan at intel.com>
> Acked-by: Jesse Barnes <jbarnes at virtuousgeek.org>
> ---
>  drivers/gpu/drm/i915/i915_drv.h   |   13 +++++++++++++
>  drivers/gpu/drm/i915/intel_bios.c |   29 +++++++++++++++++++++++++++++
>  drivers/gpu/drm/i915/intel_bios.h |   29 +++++++++++++++++++++++++++++
>  3 files changed, 71 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 728b9c3..6b4d0b20 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1218,6 +1218,12 @@ struct ddi_vbt_port_info {
>  	uint8_t supports_dp:1;
>  };
>  
> +enum drrs_support_type {
> +	DRRS_NOT_SUPPORTED = 0,
> +	STATIC_DRRS_SUPPORT = 1,
> +	SEAMLESS_DRRS_SUPPORT = 2
> +};
> +
>  struct intel_vbt_data {
>  	struct drm_display_mode *lfp_lvds_vbt_mode; /* if any */
>  	struct drm_display_mode *sdvo_lvds_vbt_mode; /* if any */
> @@ -1233,6 +1239,13 @@ struct intel_vbt_data {
>  	int lvds_ssc_freq;
>  	unsigned int bios_lvds_val; /* initial [PCH_]LVDS reg val in VBIOS */
>  
> +	/*
> +	 * DRRS support type (Seamless OR Static DRRS OR not supported)
> +	 * drrs_support type Val 0x2 is Seamless DRRS and 0 is Static DRRS.
> +	 * These values correspond to the VBT values for drrs mode.
> +	 */

The comment is wrong.

> +	enum drrs_support_type drrs_type;
> +
>  	/* eDP */
>  	int edp_rate;
>  	int edp_lanes;
> diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
> index 86b95ca..2414eca 100644
> --- a/drivers/gpu/drm/i915/intel_bios.c
> +++ b/drivers/gpu/drm/i915/intel_bios.c
> @@ -218,6 +218,25 @@ parse_lfp_panel_data(struct drm_i915_private *dev_priv,
>  
>  	panel_type = lvds_options->panel_type;
>  
> +	dev_priv->vbt.drrs_type = (lvds_options->dps_panel_type_bits
> +					>> (panel_type * 2)) & MODE_MASK;
> +	/*
> +	 * VBT has static DRRS = 0 and seamless DRRS = 2.
> +	 * The below piece of code is required to adjust vbt.drrs_type
> +	 * to match the enum drrs_support_type.
> +	 */
> +	switch (dev_priv->vbt.drrs_type) {

Please don't mix the vbt and the enum at all like this, it's error
prone. Just make the switch on the value in vbt, and for each case
assign the appropriate enum to dev_priv->vbt.drrs_type.

> +	case 0:
> +		dev_priv->vbt.drrs_type = STATIC_DRRS_SUPPORT;
> +		DRM_DEBUG_KMS("DRRS supported mode is static\n");
> +		break;
> +	case 2:
> +		DRM_DEBUG_KMS("DRRS supported mode is seamless\n");
> +		break;
> +	default:
> +		break;

And fail on the default.

> +	}
> +
>  	lvds_lfp_data = find_section(bdb, BDB_LVDS_LFP_DATA);
>  	if (!lvds_lfp_data)
>  		return;
> @@ -516,6 +535,16 @@ parse_driver_features(struct drm_i915_private *dev_priv,
>  
>  	if (driver->dual_frequency)
>  		dev_priv->render_reclock_avail = true;
> +
> +	DRM_DEBUG_KMS("DRRS State Enabled:%d\n", driver->drrs_enabled);
> +	/*
> +	 * If DRRS is not supported, drrs_type has to be set to 0.
> +	 * This is because, VBT is configured in such a way that
> +	 * static DRRS is 0 and DRRS not supported is represented by
> +	 * driver->drrs_enabled=false
> +	 */
> +	if (!driver->drrs_enabled)
> +		dev_priv->vbt.drrs_type = driver->drrs_enabled;

Don't assign a boolean to an enum.

>  }
>  
>  static void
> diff --git a/drivers/gpu/drm/i915/intel_bios.h b/drivers/gpu/drm/i915/intel_bios.h
> index 282de5e..5505d6c 100644
> --- a/drivers/gpu/drm/i915/intel_bios.h
> +++ b/drivers/gpu/drm/i915/intel_bios.h
> @@ -281,6 +281,9 @@ struct bdb_general_definitions {
>  	union child_device_config devices[0];
>  } __packed;
>  
> +/* Mask for DRRS / Panel Channel / SSC / BLT control bits extraction */
> +#define MODE_MASK		0x3
> +
>  struct bdb_lvds_options {
>  	u8 panel_type;
>  	u8 rsvd1;
> @@ -293,6 +296,18 @@ struct bdb_lvds_options {
>  	u8 lvds_edid:1;
>  	u8 rsvd2:1;
>  	u8 rsvd4;
> +	/* LVDS Panel channel bits stored here */
> +	u32 lvds_panel_channel_bits;
> +	/* LVDS SSC (Spread Spectrum Clock) bits stored here. */
> +	u16 ssc_bits;
> +	u16 ssc_freq;
> +	u16 ssc_ddt;
> +	/* Panel color depth defined here */
> +	u16 panel_color_depth;
> +	/* LVDS panel type bits stored here */
> +	u32 dps_panel_type_bits;
> +	/* LVDS backlight control type bits stored here */
> +	u32 blt_control_type_bits;
>  } __packed;
>  
>  /* LFP pointer table contains entries to the struct below */
> @@ -478,6 +493,20 @@ struct bdb_driver_features {
>  
>  	u8 hdmi_termination;
>  	u8 custom_vbt_version;
> +	/* Driver features data block */
> +	u16 rmpm_enabled:1;
> +	u16 s2ddt_enabled:1;
> +	u16 dpst_enabled:1;
> +	u16 bltclt_enabled:1;
> +	u16 adb_enabled:1;
> +	u16 drrs_enabled:1;
> +	u16 grs_enabled:1;
> +	u16 gpmt_enabled:1;
> +	u16 tbt_enabled:1;
> +	u16 psr_enabled:1;
> +	u16 ips_enabled:1;
> +	u16 reserved3:4;
> +	u16 pc_feature_valid:1;
>  } __packed;
>  
>  #define EDP_18BPP	0
> -- 
> 1.7.9.5
>
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-- 
Jani Nikula, Intel Open Source Technology Center