Re: [PATCH 03/12] drm/i915/bxt: Disable DSI PLL for BXT

From: Jani Nikula <jani.nikula@linux.intel.com>
To: Uma Shankar <uma.shankar@intel.com>, intel-gfx@lists.freedesktop.org
Cc: shobhit.kumar@intel.com
Subject: Re: [PATCH 03/12] drm/i915/bxt: Disable DSI PLL for BXT
Date: Mon, 25 May 2015 19:12:42 +0300	[thread overview]
Message-ID: <87h9r0iqkl.fsf@intel.com> (raw)
In-Reply-To: <1432310765-2218-4-git-send-email-uma.shankar@intel.com>

On Fri, 22 May 2015, Uma Shankar <uma.shankar@intel.com> wrote:
> From: Shashank Sharma <shashank.sharma@intel.com>
>
> This patch adds two new functions:
> - disable_dsi_pll.
>   BXT DSI disable sequence and registers are
>   different from previous platforms.
> - intel_disable_dsi_pll
>   wrapper function to re-use the same code for
>   multiple platforms. It checks platform type and
>   calls appropriate core pll disable function.
>
> Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
> Signed-off-by: Uma Shankar <uma.shankar@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_dsi.c     |    2 +-
>  drivers/gpu/drm/i915/intel_dsi.h     |    2 +-
>  drivers/gpu/drm/i915/intel_dsi_pll.c |   31 ++++++++++++++++++++++++++++++-
>  3 files changed, 32 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dsi.c b/drivers/gpu/drm/i915/intel_dsi.c
> index 1927546..2c0ea6f 100644
> --- a/drivers/gpu/drm/i915/intel_dsi.c
> +++ b/drivers/gpu/drm/i915/intel_dsi.c
> @@ -553,7 +553,7 @@ static void intel_dsi_clear_device_ready(struct intel_encoder *encoder)
>  		usleep_range(2000, 2500);
>  	}
>  
> -	vlv_disable_dsi_pll(encoder);
> +	intel_disable_dsi_pll(encoder);
>  }
>  
>  static void intel_dsi_post_disable(struct intel_encoder *encoder)
> diff --git a/drivers/gpu/drm/i915/intel_dsi.h b/drivers/gpu/drm/i915/intel_dsi.h
> index 20cfcf07..759983e 100644
> --- a/drivers/gpu/drm/i915/intel_dsi.h
> +++ b/drivers/gpu/drm/i915/intel_dsi.h
> @@ -122,7 +122,7 @@ static inline struct intel_dsi *enc_to_intel_dsi(struct drm_encoder *encoder)
>  }
>  
>  extern void intel_enable_dsi_pll(struct intel_encoder *encoder);
> -extern void vlv_disable_dsi_pll(struct intel_encoder *encoder);
> +extern void intel_disable_dsi_pll(struct intel_encoder *encoder);
>  extern u32 vlv_get_dsi_pclk(struct intel_encoder *encoder, int pipe_bpp);
>  
>  struct drm_panel *vbt_panel_init(struct intel_dsi *intel_dsi, u16 panel_id);
> diff --git a/drivers/gpu/drm/i915/intel_dsi_pll.c b/drivers/gpu/drm/i915/intel_dsi_pll.c
> index a58f0a1..0cbcf32 100644
> --- a/drivers/gpu/drm/i915/intel_dsi_pll.c
> +++ b/drivers/gpu/drm/i915/intel_dsi_pll.c
> @@ -267,7 +267,7 @@ static void vlv_enable_dsi_pll(struct intel_encoder *encoder)
>  	DRM_DEBUG_KMS("DSI PLL locked\n");
>  }
>  
> -void vlv_disable_dsi_pll(struct intel_encoder *encoder)
> +static void vlv_disable_dsi_pll(struct intel_encoder *encoder)
>  {
>  	struct drm_i915_private *dev_priv = encoder->base.dev->dev_private;
>  	u32 tmp;
> @@ -440,6 +440,23 @@ static void bxt_enable_dsi_pll(struct intel_encoder *encoder)
>  	DRM_DEBUG_KMS("DSI PLL locked\n");
>  }
>  
> +static void bxt_disable_dsi_pll(struct intel_encoder *encoder)
> +{
> +	struct drm_i915_private *dev_priv = encoder->base.dev->dev_private;
> +
> +	DRM_DEBUG_KMS("\n");
> +
> +	/* Disable DSI PLL */

That is obvious from the code.

> +	I915_WRITE(BXT_DSI_PLL_ENABLE, 0);
> +
> +	/* Should timeout and fail if not locked after 200 us */
> +	if (wait_for((I915_READ(BXT_DSI_PLL_ENABLE)
> +					& BXT_DSI_PLL_LOCKED) == 0, 1)) {
> +		DRM_ERROR("Disable: DSI PLL not locked\n");

not unlocked?

> +		return;

Unnecessary return statement.

> +	}
> +}
> +
>  void intel_enable_dsi_pll(struct intel_encoder *encoder)
>  {
>  	struct drm_device *dev = encoder->base.dev;
> @@ -451,3 +468,15 @@ void intel_enable_dsi_pll(struct intel_encoder *encoder)
>  	else
>  		DRM_ERROR("Invalid DSI device to pre_pll_enable\n");
>  }
> +
> +void intel_disable_dsi_pll(struct intel_encoder *encoder)
> +{
> +	struct drm_device *dev = encoder->base.dev;
> +
> +	if (IS_VALLEYVIEW(dev))
> +		vlv_disable_dsi_pll(encoder);
> +	else if (IS_BROXTON(dev))
> +		bxt_disable_dsi_pll(encoder);
> +	else
> +		DRM_ERROR("Invalid DSI device to pre_pll_enable\n");

Please drop the else branch.

BR,
Jani.

> +}
> -- 
> 1.7.9.5
>
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-- 
Jani Nikula, Intel Open Source Technology Center
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