Re: [PATCH 1/2] dt-bindings: fpga: zynq: Document ICAP on boot

Krzysztof Kozlowski
2025-03-31T12:44:07Z

On 31/03/2025 14:30, Sam Winchenbach wrote:
>>
>>> + type: boolean
>>> + description: If present, the ICAP controller will be enabled when
>>> + the driver probes. This is useful if the fabric is loaded
>>> + during the boot process and contains a core, such as the SEM,
>>
>> I don't get how this is suitable for DT. If you decide to load the
>> fabric from driver, that's driver decision so not DT.
>
> Before writing the fabric to the FPGA the driver disables the ICAP, enabling
> the PCAP. Once writing is complete it unconditionally disables the PCAP,
> enabling the ICAP. This patch just makes it so, depending on the use case,
> the ICAP can be enabled at boot. This will not prevent the system from being
> able to load a fabric through the driver. I added in this boolean so existing
> behavior would be maintained.
>
> Do you recommend another approach such as writing to a sysfs attribute to
> switch from PCAP to ICAP?
Not sure yet. Can't you check the status of ICAP before programming and
then enable it only if was enabled before?

Best regards,
Krzysztof