Re: [BUG] simplefb not showing any output

On 09/07/2013 06:25 AM, David Herrmann wrote:

On Sat, Sep 7, 2013 at 1:47 PM, Tom Gundersen [off-list ref] wrote:

...

quoted

A related question: is it expected that simplefb should be
significantly slower than efifb, or is that something worth looking
into? My boot with simplefb is roughly five seconds slower than with
efifb. Coincidentally, I notice the same (or similar slowdown) with
inteldrmfb when I see the oops (but not otherwise).

That is probably related to the missing write-combine tag in ioremap.
Stephen, any objections to this attached patch?
Tom, if this solves the speed-issues, I will send it out once I get home.

Thanks
David

(Patch also attached in case of new-lines issues)

From dbfb8e12166d494cd60823cbe84134d5d1a73ec8 Mon Sep 17 00:00:00 2001
From: David Herrmann <redacted>
Date: Sat, 7 Sep 2013 14:22:01 +0200
Subject: [PATCH] devm/simplefb: introduce and use devm_ioremap_wc()

We want to use devm_ioremap_nocache() or even devm_ioremap_wc() to speed
up fbdev writes _a lot_. As devm_ioremap_wc() doesn't exist, yet,
introduce it along the way. Note that ioremap_wc() is aliases to
ioremap_nocache() in asm-generic/{io,iomem}.h so we can safely expect all
architectures to either provide it or use the same alias.

I'm fine with this so long as wc mappings are always possible, or
automatically fall back to uc if not. This certainly works on Tegra, and
I'll try to remember to test it on Raspberry Pi tonight.