Re: [PATCH v45 2/7] mailbox/pcc.c: ignore errors on type 4 channels.

[Adam Young <admiyo@amperemail.onmicrosoft.com>]

On 7/22/26 04:55, Sudeep Holla wrote:
> On Tue, Jul 21, 2026 at 01:52:51PM -0400, Adam Young wrote:
>> THE ACPI spec states:
>>
>> "[The Error status register] Contains the processor relative address,
>> represented in Generic Address Structure (GAS) format, of the Error status
>> register. This field is ignored by the OSPM on slave channels"
>>
> Does anyone have these error status register for Type 4 ? If not it can
> be optimised with that check rather than channel type check. I would rather
> avoiding adding checks on the type of the channel everywhere in the code.
>
The requirement that errors are ignored is strange and I have no 
visibility into why it is included.  It may be completely safe to ignore 
this rule. We have not tripped over it in our hardware, which is why I 
did not address it before. I cannot speak for any other 
implementations.  However, I think the exclusion needs to be here for 
compliance with the protocol, otherwise we might end up with a case that 
we cannot support.  If you can suggest an alternate way to implement the 
specification, please let me know and I will try to encode it.