Re: [RFC] PCI: add support for Immediate Readiness

[Felipe Balbi <felipe.balbi@linux.intel.com>]

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Sinan Kaya <okaya@kernel.org> writes:

> On 8/2/2018 7:36 AM, Felipe Balbi wrote:
>> PCIe GEN4 defines a new bit on Status Register which tells us that, if
>> Set, a function is immediately ready after a Reset. This means that
>> all delays after a Conventional or Function Reset can be skipped.
>
> Can you give a reference to the section of the specification? or
> a pointer to the ECN?

Section 7.5.1.1.4 of PCIe GEN4 spec. Table 7-4:

Immediate Readiness – This optional bit, when Set, indicates the
Function is guaranteed to be ready to successfully complete valid
configuration accesses at any time following any reset that the host is
capable of issuing Configuration Requests to this Function.

When this bit is Set, for accesses to this Function, software is exempt
from all requirements to delay configuration accesses following any type
of reset, including but not limited to the timing requirements defined
in Section 6.6.  How this guarantee is established is beyond the scope
of this document.

It is permitted that system software/firmware provide mechanisms that
supersede the indication provided by this bit, however such
software/firmware mechanisms are outside the scope of this
specification.

-- 
balbi

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