[U-Boot] Testing Data Cache for armv7 (beagleboard)

[Ghorai, Sukumar]

> -----Original Message-----
> From: u-boot-bounces at lists.denx.de [mailto:u-boot-bounces at lists.denx.de]
> On Behalf Of chris c
> Sent: Tuesday, October 12, 2010 6:55 AM
> To: u-boot at lists.denx.de
> Subject: Re: [U-Boot] Testing Data Cache for armv7 (beagleboard)
> 
> Thanks for the replies.  I didn't realize that the MMC module was
> operating
> in 1-bit mode inside U-boot.  I'll concentrate on looking at that.  Has
> anybody done any work to try and get 4-bit mode working for OMAP3 in
> U-boot?

[Ghorai] can you give a test using this patch series? This uses the generic mmc/sd driver for beagle board. And mmc/sd card will work at 4-bit, 48Mhz.
http://www.mail-archive.com/u-boot@lists.denx.de/msg38690.html

> 
> Thanks,
> Chris
> 
> On Thu, Oct 7, 2010 at 1:04 PM, Wolfgang Denk <wd at denx.de> wrote:
> 
> > Dear chris c,
> >
> > In message
> <AANLkTi=usuEyf4YuUVWrrLu80bMRFpRF+BThEix2bFNg at mail.gmail.com<usuEyf4YuUVW
> rrLu80bMRFpRF%2BBThEix2bFNg at mail.gmail.com>>
> > you wrote:
> > >
> > > I was comparing time just by timing it manually.  How did you
> instrument
> > > u-boot to display the time?
> >
> > That's no instrumentation of U-Boot, but just timestamping the output
> > on the serial console. See for example
> > ftp://ftp.denx.de/pub/tools/time_log
> >
> > > As for the small versus large file, I did the same test for 1MB of
> data
> > > using nand read and saw a x4 performance advantage.  I also did a test
> on
> > > mmc with 100 MB file and saw no performance increase.  Looks like file
> > size
> > > doesn't matter.
> > >
> > > So does that mean that MMC file loading will not benefit from dcache
> > > enabled?  Can anybody explain this?
> >
> > It depends on where the time is actually spent. If you have a slow
> > (say, bit-banging) MMC driver and a low-performance CPU then the
> > transfer from MMC might simply not depend as much on caches. It is
> > wrong to check just a simple use case. Try a number of different
> > operations, like umcompressing a large image in RAM or from NOR to
> > RAM, or downloading over the net, or ...
> >
> > Best regards,
> >
> > Wolfgang Denk
> >
> > --
> > DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
> > HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
> > Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
> > "Remember, Information is not knowledge;  Knowledge  is  not  Wisdom;
> > Wisdom is not truth; Truth is not beauty; Beauty is not love; Love is
> > not music; Music is the best."                          - Frank Zappa
> >