Re: [PATCH v4] cdx: add MSI support for CDX bus

Gupta, Nipun
2023-10-05T15:48:29Z

On 10/5/2023 8:24 PM, Greg KH wrote:
> On Thu, Oct 05, 2023 at 08:07:35PM +0530, Gupta, Nipun wrote:
>> Hi Greg,
>>
>> On 10/5/2023 7:30 PM, Greg KH wrote:
>>> On Thu, Oct 05, 2023 at 03:46:34PM +0200, Thomas Gleixner wrote:
>>>> On Thu, Oct 05 2023 at 12:24, Greg KH wrote:
>>>>>> diff --git a/drivers/cdx/Kconfig b/drivers/cdx/Kconfig
>>>>>> index a08958485e31..86df7ccb76bb 100644
>>>>>> --- a/drivers/cdx/Kconfig
>>>>>> +++ b/drivers/cdx/Kconfig
>>>>>> @@ -8,6 +8,7 @@
>>>>>> config CDX_BUS
>>>>>> bool "CDX Bus driver"
>>>>>> depends on OF && ARM64
>>>>>> + select GENERIC_MSI_IRQ_DOMAIN
>>>>>
>>>>> This config option isn't in my tree anywhere, where did it come from?
>>>>> What is it supposed to do?
>>>>
>>>> 13e7accb81d6 ("genirq: Get rid of GENERIC_MSI_IRQ_DOMAIN") :)
>>>
>>> Ok, so this hasn't been tested since the 6.2 release? Wow, I think
>>> someone from AMD needs to take a deep look at this and verify that it
>>> actually is doing what it is supposed to be doing...
>>
>> The patch Thomas mentioned renames "GENERIC_MSI_IRQ_DOMAIN" to
>> "GENERIC_MSI_IRQ"; and in our testing "GENERIC_MSI_IRQ" is also selected as
>> 'ARM64' is enabled which enables 'ARM_GIC_V3_ITS' which in-turn selects
>> 'GENERIC_MSI_IRQ'.
>
> Ok, but that's not what this patch "selects" at all :(

"GENERIC_MSI_IRQ" gets enabled because of enabling "ARM64", and you are
right that what we are selecting here does not have any meaning now
(after 6.2).

>
>> The patch is tested for MSI functionality on 6.6-rc1. We will re-look into
>> the config dependencies to avoid such issues, but please be assured that the
>> patch has been validated.
>
> How has the dependancy been validated as correct if there is no such
> thing in this kernel?

Apology for the confusion. By validated I meant tested for MSI
functionality in CDX. Agree that "select GENERIC_MSI_IRQ_DOMAIN" needs
to be fixed here. Will update in next spin. :)

Thanks,
Nipun

>
> confused,
>
> greg k-h