On Tue, May 14, 2019 at 09:00:19AM +0530, Vidya Sagar wrote:
> On 5/13/2019 12:55 PM, Christoph Hellwig wrote:
> > On Mon, May 13, 2019 at 10:36:13AM +0530, Vidya Sagar wrote:
> > > Export pcie_pme_disable_msi() & pcie_pme_no_msi() APIs to enable drivers
> > > using these APIs be able to build as loadable modules.
> >
> > But this is a global setting. If you root port is broken you need
> > a per-rootport quirk instead.
> >
> There is nothing broken in Tegra194 root port as such, rather, this
> is more of software configuration choice and we are going with
> legacy interrupts than MSI interrupts (as Tegra194 doesn't support
> raising PME interrupts through MSI and please note that this doesn't
> mean root port is broken).
I think the port *is* broken. PCIe r4.0, sec 6.1.6, says
If the Root Port is enabled for edge-triggered interrupt signaling
using MSI or MSI-X, an interrupt message must be sent every time the
logical AND of the following conditions transitions from FALSE to
TRUE:
* The associated vector is unmasked (not applicable if MSI does
not support PVM).
* The PME Interrupt Enable bit in the Root Control register is set
to 1b.
* The PME Status bit in the Root Status register is set.
The Tegra194 root port advertises MSI support, so the above should
apply.
> Since Tegra194 has only Synopsys DesignWare core based host
> controllers and not any other hosts, I think it is fine to call this
> API in driver.
It's fine to add a per-device quirk to set pdev->no_msi or something
similar.
Bjorn
