Messages in this thread | | | Subject | Re: [PATCH V2 03/10] irqchip,GICv3,ACPI: Add redistributor support via GICC structures. | From | Tomasz Nowicki <> | Date | Tue, 12 Jan 2016 18:14:25 +0100 |
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On 12.01.2016 17:16, Marc Zyngier wrote: >>> >>Also, the spec says: >>> >> >>> >>"On systems supporting GICv3 and above, this field holds the 64-bit >>> >>physical address of the associated Redistributor. If all of the GIC >>> >>Redistributors are in the always-on power domain, GICR structures should >>> >>be used to describe the Redistributors instead, and this field must be >>> >>set to 0." >>> >> >>> >>which triggers two questions: >>> >>- Can you access always the GICR_TYPER register without waking the >>> >>redistributor up? >> > >> >I missed this part, can you suggest how can we do that? accessing some >> >register before access to redistributor? > This redistributor may be in a power-domain that is off. Are you > guaranteed that you can access GICR_TYPER even when it is off? > >> > >>> >>- How do you cope with situations where some redistributors are in the >>> >>always-on domain, and some are not? >> > >> >I'm not sure if there is such hardware, if yes, do we need to fix >> >the spec first? > It is something that should definitely be clarified. Can we end-up in a > situation where some redistributors are described via the GICR > structure, and some via the GICC structure? The spec is a bit ambiguous. >
To recap: 1. GICR and GICC subtables should be mutually exclusive, but ACPI spec should be clear about this. 2. We need to know if we can access GICR_TYPER without waking the redistributor up.
Tirumalesh, can you please advice?
Tomasz
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