[meta-xilinx] load fpga bitstream in u-boot SPL on pyro

yohan.boyer at ioterop.com yohan.boyer at ioterop.com
Fri Oct 13 07:03:30 PDT 2017

>> There is not the patch zynq-Add-fpga-support-to-u-boot-SPL.patch in pyro.
>That patch was removed as it was never upstreamed or updated for newer u-boot's, and was replaced with the >auto generated uEnv.txt which uses U-Boot to do the bitstream loading by default.


>> So my question is : Am I missing something ?
>> I think u-boot can’t read the MAC address if the bitstream is not 
>> loaded before u-boot try to read it.
>That is right, its a limitation of using the PL for I2C EEPROM which provides boot data, the same limits apply to >most u-boot functionality if the device being accessed is in the PL.
>If you are making a design that has the MAC address in an I2C EEPROM, I would recommend that you attach it to >the MIO I2C, or if you are using SPI flash store it there.
>If you are stuck with using the I2C EEPROM via the PL you have a number of options, here are just some ideas >that come to mind.

Thank you Nathan !
I hesitate between 2 of these solutions. 
Option 1 is a bit stuffed !
The option 2 or the option 3 are nice. I'm not familiar with patch and u-boot though.
Which will be the most easy to your mind ? And do you have an idea where should I begin ?
The option 4 is impossible because it need access ethernet during u-boot. 

>* Do some trickery with U-Boot and environment setup to run U-Boot loading the bitstream then re-load U-Boot
>* Modify U-Boot to allow reloading of the MAC via a cmd, which is executed after you have loaded the bitstream
>* Use the SPL patch to load the bitstream early
>* On first boot into linux load the EEPROM content and store it in the u-boot environment in the flash/etc. Or >just load it in linux if you are not using the ethernet during boot.

>> Also, I find in pyro the uenv.txt is generated, very nice !
>> But in case the bitstream will be load in u-boot SPL, it will cause issue ?
>> Since the uenv.txt load it in u-boot.

>You would just be loading the bitstream twice which would slow the boot time down. But it should be >functional. Though you can remove the bitstream load from the uEnv.txt.

Ok, no problem with that.



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