Re: SM501: Implement acceleration features

[Ben Dooks]

Vincent Sanders wrote:
> On Wed, Nov 11, 2009 at 12:58:25AM +0100, Krzysztof Helt wrote:
> > On Tue, 10 Nov 2009 17:18:10 +0000
> > Ben Dooks <ben@xxxxxxxxxxxx> wrote:
> >
> > > From: Vincent Sanders <vince@xxxxxxxxxxxx>
> > >
> > > This patch provides the acceleration entry points for the SM501
> > > framebuffer driver.
> > >
> > > This patch provides the sync, copyarea and fillrect entry points,
> > > using the SM501's 2D acceleration engine to perform the operations
> > > in-chip rather than across the bus.
> > >
> > > Signed-off-by: Vincent Sanders <vince@xxxxxxxxxxxx>
> > > Signed-off-by: Simtec Linux Team <linux@xxxxxxxxxxxx>
> > > Signed-off-by: Ben Dooks <ben@xxxxxxxxxxxx>
> > >
> > > ---
> > >  drivers/video/sm501fb.c    |  238 ++++++++++++++++++++++++++++++++++++++++++---
> > >  include/linux/sm501-regs.h |    2 
> > >  2 files changed, 226 insertions(+), 14 deletions(-)
> > >
> > > Index: b/drivers/video/sm501fb.c
> > > ===================================================================
> > > --- a/drivers/video/sm501fb.c	2009-11-03 11:19:44.000000000 +0000
> > > +++ b/drivers/video/sm501fb.c	2009-11-03 11:19:46.000000000 +0000
>
> I have snipped all but small amount for context
>
> > > +	/* wait for the 2d engine to be ready */
> > > +	while ((count > 0) &&
> > > +	       (readl(fbi->regs + SM501_SYSTEM_CONTROL) &
> > > +		SM501_SYSCTRL_2D_ENGINE_STATUS) != 0)
> > > +		count--;
> > > +
> > You may add cpu_relax() inside this loop.
>
> ok, would need to test this thoroughly as the SM501 has some...odd
> behaviours (see later on).
>
> > > +
> > > +	if (sm501fb_sync(info))
> > > +		return;
> > > +
> > Please check if you need to wait for the blit engine before writting
> > to any register.  Usually, the values in the bit engine registers
> > are shadowed after the engine is started (ie. the blitting operation
> > is started) and the next set of values can be written into the regs.
>
> indeed, if it were sane I would agree, it isnt in all circumstances, see later

It might be worth caching the data that relies on bpp after set_par
call, and thus avoiding another swtich on bpp in the acceleration
routines.

Otherwise not much else to say.

--
Ben Dooks, Software Engineer, Simtec Electronics

http://www.simtec.co.uk/
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/