linux-kernel - Re: [Intel-gfx] [PATCH 2/7] drm/i915: FDI B/C share 4 lanes on Ivybridge

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Date:	Fri, 17 Aug 2012 16:12:54 +0100
From:	"Lespiau, Damien" <damien.lespiau@...el.com>
To:	Keith Packard <keithp@...thp.com>
Cc:	intel-gfx@...ts.freedesktop.org,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: [Intel-gfx] [PATCH 2/7] drm/i915: FDI B/C share 4 lanes on Ivybridge

On Fri, Aug 17, 2012 at 4:00 PM, Keith Packard <keithp@...thp.com> wrote:
>> I guess this does not cover the case of pipe B using 3 lanes meaning
>> pipe C can use 1?
>
> It didn't look like that was a supported mode from the docs.

Ah yes, found it now "FDI B maximum port width is 4 lanes when FDI C
is disabled, 2 lanes when FDI C is enabled."

>> This duplicates the code just that is just a few lines away, instead
>> how about moving the logic to set target_clock up in front of this
>> whole if()?
>
> It's not the same, it's the inverse -- computing bpp from lanes+clock
> clock instead of computing lanes from bpp+clock. But, yeah, it would be
> nice to have these merged somehow. I couldn't figure out a good way though.

I meant the

> +               if (is_dp)
> +                       target_clock = mode->clock;
> +               else
> +                       target_clock = adjusted_mode->clock;

Just after that else block you have

        /* [e]DP over FDI requires target mode clock instead of link clock. */
        if (edp_encoder)
                target_clock = intel_edp_target_clock(edp_encoder, mode);
        else if (is_dp)
                target_clock = mode->clock;
        else
                target_clock = adjusted_mode->clock;

Those look strangely similar to me. The later could be moved up.

-- 
Damien
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