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.
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
