[U-Boot] [PATCH 00/35][RFC] arm: socfpga: Usability fixes

[Marek Vasut]

On Friday, September 19, 2014 at 11:44:48 AM, Chin Liang See wrote:
> Dear Wolfgang,
> 
> On Wed, 2014-09-17 at 16:11 +0200, ZY - wd wrote:
> > Dear Chin Liang See,
> > 
> > In message <1410952049.7769.11.camel at clsee-VirtualBox.altera.com> you wrote:
> > > Hmmm... actually I can get it works well for my Altera dev kit. The
> > > get_dram_size would take in the argument PHYS_SDRAM_1_SIZE. From here,
> > > the function will ensure the memory specified can read and writable. If
> > > its failing here, probably the SDRAM access might have issue. FYI,
> > > PHYS_SDRAM_1_SIZE is 0x40000000 for 1GB.
> > 
> > Normally, get_dram_size() would be called with a size argument that is
> > _larger_ (twice as big) as the biggest possible memory configuration
> > on the respective device.  Otherwise it can only detect smaller memory
> > sizes, but would fail to detect if a bigger memory device is
> > installed by accident.
> 
> Yup, you are right. But currently, the memory space after the SDRAM is a
> bridge to FPGA. We will get data abort when trying to read that area
> (for a blank FPGA).

This is good, no ? If you reliably get DABT if the H2F bridge is disabled, you 
can place the trampoline into the DABT vector and detect DRAM size. I'll have to 
test this.

> I believe Marek's suggestion to work around the DABT and memory
> detection would work around SOCFPGA memory detection. Its something we
> would work closely with Marek to enable this auto detection.

OK ;-)

Best regards,
Marek Vasut