Re: [PATCH 06/11] drm/i915: Add intel_dotclock_calculate()

[Jani Nikula <jani.nikula@linux.intel.com>]

On Fri, 06 Sep 2013, ville.syrjala@linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> Extract the code to calculate the dotclock from the link clock and M/N
> values into a new function from ironlake_crtc_clock_get().
>
> The new function can be used to calculate the dotclock for both FDI and
> DP cases.
>
> Also simplify the code a bit along the way.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_display.c | 40 +++++++++++++++---------------------
>  drivers/gpu/drm/i915/intel_drv.h     |  2 ++
>  2 files changed, 19 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index b3049a6..c393c8e 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -7410,16 +7410,9 @@ static void i9xx_crtc_clock_get(struct intel_crtc *crtc,
>  	pipe_config->adjusted_mode.clock = clock.dot;
>  }
>  
> -static void ironlake_crtc_clock_get(struct intel_crtc *crtc,
> -				    struct intel_crtc_config *pipe_config)
> +int intel_dotclock_calculate(int link_freq,
> +			     const struct intel_link_m_n *m_n)
>  {
> -	struct drm_device *dev = crtc->base.dev;
> -	struct drm_i915_private *dev_priv = dev->dev_private;
> -	enum transcoder cpu_transcoder = pipe_config->cpu_transcoder;
> -	int link_freq;
> -	u64 clock;
> -	u32 link_m, link_n;
> -
>  	/*
>  	 * The calculation for the data clock is:
>  	 * pixel_clock = ((m/n)*(link_clock * nr_lanes))/bpp
> @@ -7430,6 +7423,18 @@ static void ironlake_crtc_clock_get(struct intel_crtc *crtc,
>  	 * link_clock = (m * link_clock) / n
>  	 */
>  
> +	if (!m_n->link_n)
> +		return 0;
> +
> +	return div_u64((u64)m_n->link_m * link_freq, m_n->link_n);
> +}
> +
> +static void ironlake_crtc_clock_get(struct intel_crtc *crtc,
> +				    struct intel_crtc_config *pipe_config)
> +{
> +	struct drm_device *dev = crtc->base.dev;
> +	int link_freq;
> +
>  	/*
>  	 * We need to get the FDI or DP link clock here to derive
>  	 * the M/N dividers.
> @@ -7438,21 +7443,10 @@ static void ironlake_crtc_clock_get(struct intel_crtc *crtc,
>  	 * For DP, it's either 1.62GHz or 2.7GHz.
>  	 * We do our calculations in 10*MHz since we don't need much precison.
>  	 */
> -	if (pipe_config->has_pch_encoder)
> -		link_freq = intel_fdi_link_freq(dev) * 10000;
> -	else
> -		link_freq = pipe_config->port_clock;

The new code loses this distinction. I don't know if it matters. Please
explain.

> -
> -	link_m = I915_READ(PIPE_LINK_M1(cpu_transcoder));
> -	link_n = I915_READ(PIPE_LINK_N1(cpu_transcoder));
> -
> -	if (!link_m || !link_n)
> -		return;
> -
> -	clock = ((u64)link_m * (u64)link_freq);
> -	do_div(clock, link_n);
> +	link_freq = intel_fdi_link_freq(dev) * 10000;
>  
> -	pipe_config->adjusted_mode.clock = clock;
> +	pipe_config->adjusted_mode.clock =
> +		intel_dotclock_calculate(link_freq, &pipe_config->fdi_m_n);

I'm not sure if the fear in unwarranted, but can we always be sure
fdi_m_n has been set?

Jani.


>  }
>  
>  /** Returns the currently programmed mode of the given pipe. */
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index a4e8689..4cf8898 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -803,5 +803,7 @@ extern void intel_aux_display_runtime_get(struct drm_i915_private *dev_priv);
>  extern void intel_aux_display_runtime_put(struct drm_i915_private *dev_priv);
>  extern void intel_dp_get_m_n(struct intel_crtc *crtc,
>  			     struct intel_crtc_config *pipe_config);
> +extern int intel_dotclock_calculate(int link_freq,
> +				    const struct intel_link_m_n *m_n);
>  
>  #endif /* __INTEL_DRV_H__ */
> -- 
> 1.8.1.5
>
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-- 
Jani Nikula, Intel Open Source Technology Center
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