On Fri, Aug 17, 2018 at 7:05 AM Ramon Fried <ramon.fried@xxxxxxxxx> wrote:
>
>
>
> On Thu, Aug 16, 2018 at 5:28 PM Alan Douglas <adouglas@xxxxxxxxxxx> wrote:
>>
>> Hi Ramon,
>>
>> On 15 August 2018 17:56, Ramon Fried wrote:
>> > On August 15, 2018 4:46:21 PM GMT+03:00, Alan Douglas <adouglas@xxxxxxxxxxx> wrote:
>> > >The patch implements MSI-X support in the cadence endpoint driver.
>> > >
>> > >This patch depends on on Gustavo Pimentel's patch series adding MSI-X
>> > >support for EP ("Add MSI-X support on pcitest tool")
>> > >
>> > >It also adds fixes for MSI issues discovered during testing of MSI-X
>> > > - Use AXI region 0 for interrupt signalling
>> > > - Write MSI and MSI-X with 32bit value rather than 16bit
>> > > - Check for masking before sending MSI or MSI-X
>> > > - Check link is up before sending IRQ
>> > >
>> > Hi.
>> > AFAIK the BIOS allocates physical memory for the bars. Assuming that the MSIx bar is only mapped after kernel boots on the endpoint,
>> > could it be too late?
>> >
>> > Do we need to trigger re-enumeration of the PCI bus from host side when working with this as an endpoint?
>> It depends on how you are using it. PF0 is always enabled in the cadence HW, so will be enumerated at boot,
>> as long as the EP HW is out of reset and PHY is enabled.
>> The PCIe EP hardware can be initialized so that BARs are enabled by default, before the kernel boots on the
>> endpoint, and so they will be found and mapped during the initial enumeration and you don't need to
>> re-enumerate. The MSI-X vectors can't be written to the BAR until the EP kernel has booted and the EP driver
>> has mapped the BAR to local EP memory though (unless you also configure this in the PCIe EP hardware, or in
>> EP pre-boot, but in that case you are probably not using the EP driver framework.)
>>
>> The EP driver framework does, in my understanding, generally expect re-enumeration after the
>> EP kernel has booted and the driver has been initialized, since it allows configuration of device ID, BAR
>> sizes etc., and if you change any of these from the HW defaults at boot you will need to re-enumerate.
>>
This basically means that this driver is for hobbyist / enthusiast,
you can't base a real product expecting
re-enumeration of the bus. right ?
>
>> All tests I have done for the EP driver have been without BIOS enumeration, and triggering re-enumeration
>> after initializing the BAR sizes etc. via the EP driver
>>
>> Regards,
>> Alan
>>
