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gpio speed - u-boot vs kernel

ranchu
Guru 20755 points

Hello,

I need to program fpga using c files module, which uses gpio pins (the gpio are used as jtag connected to fpga).

I have some dillema and wanted your advise.

Do you think it is possible to do this from both u-boot and kernel (the module need to read file from flash and then program it using gpio) ?

If yes - which is expected to have a better performance (reading from flash, and then using gpio for the programming) , u-boot or kernel ?

Thank you!

Ran

  • 0
    TI__Guru**** 161600 points

    Hi Ran,

    It is possible to use gpio in both kernel & u-boot.

    GPIO functionality is described in the General-Purpose Input/Output chapter of your device TRM. By the way which device do you use?  Which linux/u-boot version are you planning to use?

    For u-boot you will have to do some modifications: enable clocks, configure pinmux, etc. For available gpio commands check u-boot/common/cmd_gpio.c  

    For kernel configurations follow: http://processors.wiki.ti.com/index.php?title=Linux_PSP_GPIO_Driver_Guide&redirect=no#Kernel_Level 

    Ran Shalit said:
    which is expected to have a better performance (reading from flash, and then using gpio for the programming) , u-boot or kernel ?

    GPIO interface should have similar transfer speed in both u-boot & kernel.

    In my opinion operations performed from u-boot are cleaner, I mean there are no external processes that may interfere, as opposed to kernel level.  But as I said you will have to do some gpio configurations (clocking, pinmuxing) from scratch.

    Hope this helps.

    Best Regards,
    Yordan