[U-Boot] arm: socfpga: Question about FPGA/HPS SDRAM Bridge

[Marek Vasut <marex@denx.de>]

On Tuesday, September 01, 2015 at 10:41:31 AM, Jian Luo wrote:
> Hi!

Hi,

> I've read about an implementation requirement regarding the usage of
> FPGA/HPS SDRAM bridge.
> (Link and Text attached at the end.)
> 
> The 3. step involves writing the APPLYCFG bit in the STATICCFG register
> while the SDRAM interface is completely IDLE.
> IMHO, it's only possible in SPL stage where everything runs in SRAM.
> FPGA however can not be configured until U-Boot is ready (step 2).
> So warm reset should be performed after FPGA configuration.
> 
> My idea is to patch sdram.c to dynamically write FPGAPORTRST and
> APPLYCFG based on information in sysmgr_regs->romcodegrp_bootromswstate.
> 
> Is any one working on this?

We do this sort of stuff by running code from cache, see 
socfpga_sdram_apply_static_cfg() in arch/arm/mach-socfpga/misc.c .

You want to use the "bridge enable" and "bridge disable" commands
to enable/disable the bridges between FPGA and HPS in U-Boot.

Hope that helps ;-)

Best regards,
Marek Vasut