From: Ben Widawsky <ben@bwidawsk.net>
To: Chris Wilson <chris@chris-wilson.co.uk>,
Ben Widawsky <benjamin.widawsky@intel.com>,
Intel GFX <intel-gfx@lists.freedesktop.org>,
Jesse Barnes <jbarnes@virtuousgeek.org>
Subject: Re: [PATCH 4/4] drm/i915: Reserve space for FBC (fbcon)
Date: Mon, 30 Jun 2014 20:34:53 -0700 [thread overview]
Message-ID: <20140701033453.GA981@bwidawsk.net> (raw)
In-Reply-To: <20140619192811.GD8476@nuc-i3427.alporthouse.com>
On Thu, Jun 19, 2014 at 08:28:11PM +0100, Chris Wilson wrote:
> On Thu, Jun 19, 2014 at 12:06:13PM -0700, Ben Widawsky wrote:
> > This is one part in a few fixes needed to make FBC work with limited
> > stolen memory and large resolution displays. It is not the full
> > solution, but one (easy) step.
> >
> > The patch is straight-forward, it attempts to check there will be room
> > for FBC before trying to "reclaim"
>
> But it special cases one particular allocation. Why don't you just
> reserve stolen upfront for FBC? Compute the maximum buffer size the
> hardware could support and try to claim it during stolen init.
> -Chris
>
I agree this would be the best approach (and what I had planned to do).
For one, I didn't find the interfaces I wanted in the drm_mm to do what
I needed (though I didn't look very hard). I ended up getting stuck with
having to decide whether to reclaim the scanout (and fastboot), or FBC.
I believe this should be a decision left to the user, where user is the
distro packaging.
I'd like to just point out some math at this point too.
Common stolen size is 32M
3840 x 2160 x 4 = 31.64M
So we have a real problem if we want to reuse any of stolen memory,
which the first 3 patches address to some extent.
Anyway, I think I was pretty clear that the patch is incomplete, and
primarily meant to motivate the relevant parties to figure out how they
want to handle the stolen reclaim.
--
Ben Widawsky, Intel Open Source Technology Center
next prev parent reply other threads:[~2014-07-01 3:35 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-19 19:06 [PATCH 1/4] drm/i915: Move compressed_fb to static allocation Ben Widawsky
2014-06-19 19:06 ` [PATCH 2/4] drm/i915: Extract CFB threshold calculation Ben Widawsky
2014-07-01 0:16 ` Rodrigo Vivi
2014-06-19 19:06 ` [PATCH 3/4] drm/i915: Try harder to get FBC Ben Widawsky
2014-06-20 15:56 ` Runyan, Arthur J
2014-06-20 16:55 ` Ben Widawsky
2014-06-30 17:41 ` [PATCH] " Rodrigo Vivi
2014-07-01 16:09 ` Rodrigo Vivi
2014-07-03 11:52 ` Jani Nikula
2014-06-19 19:06 ` [PATCH 4/4] drm/i915: Reserve space for FBC (fbcon) Ben Widawsky
2014-06-19 19:28 ` Chris Wilson
2014-06-19 19:41 ` Ben Widawsky
2014-07-01 3:34 ` Ben Widawsky [this message]
2014-07-01 0:15 ` [PATCH 1/4] drm/i915: Move compressed_fb to static allocation Rodrigo Vivi
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