Re: [PATCH 1/7 resend] drm/i915: Add the support of eDP on DP-D for Ibex/CPT

[Chris Wilson <chris@chris-wilson.co.uk>]

On Sat, 12 Jun 2010 14:32:21 +0800, Zhenyu Wang <zhenyuw@linux.intel.com> wrote:
> From: Zhao Yakui <yakui.zhao@intel.com>
> 
> This one adds support for eDP that connected on PCH DP-D port
> instead of CPU DP-A port, and only DP-D port could be used for eDP.
> 
> https://bugs.freedesktop.org/show_bug.cgi?id=27220
> 
> Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
> Tested-by: Jan-Hendrik Zab <jan@jhz.name>
> Tested-by: Templar <templar@rshc.de>
> Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
> ---
[snip]
>  static void
> -intel_dp_compute_m_n(int bytes_per_pixel,
> +intel_dp_compute_m_n(int bpp,
>  		     int nlanes,
>  		     int pixel_clock,
>  		     int link_clock,
>  		     struct intel_dp_m_n *m_n)
>  {
>  	m_n->tu = 64;
> -	m_n->gmch_m = pixel_clock * bytes_per_pixel;
> +	m_n->gmch_m = (pixel_clock * bpp) >> 3;
>  	m_n->gmch_n = link_clock * nlanes;
>  	intel_reduce_ratio(&m_n->gmch_m, &m_n->gmch_n);
>  	m_n->link_m = pixel_clock;

This rounds the gmch_m down. Is this correct? And how close to overflow
is pixel_clock today?
-ickle

-- 
Chris Wilson, Intel Open Source Technology Centre