[PATCH 0/3] DWC host without MSI controller

[Lucas Stach]

Hi Fabio,

Am Montag, den 09.10.2017, 09:14 -0300 schrieb Fabio Estevam:
> Hi Bjorn,
> 
> On Mon, Aug 28, 2017 at 1:59 PM, Tim Harvey <tharvey at gateworks.com>
> wrote:
> > On Mon, Aug 28, 2017 at 7:23 AM, Lucas Stach <l.stach at pengutronix.d
> > e> wrote:
> > > Hi all,
> > > 
> > > this small series tries to fix/workaround a serious design flaw
> > > of the DWC PCIe
> > > host controller: it is unable to work with both legacy and MSI
> > > IRQs enabled at
> > > the same time. As soon as the first MSI is enabled in the DWC MSI
> > > controller,
> > > the host stops forwarding legacy IRQs.
> > > 
> > > If the MSI controller is present, MSIs will be used for the PCIe
> > > port services
> > > IRQs, leaving endpoint devices which don't support MSIs unable to
> > > raise IRQs.
> > > It is only safe to enable the MSI controller if it is validated
> > > that all PCIe
> > > devices and drivers in the system support working MSIs. As most
> > > devices
> > > support falling back to using legacy PCIe IRQs if MSI support is
> > > missing it is
> > > much safer to disable the MSI by default and only enable it on
> > > validated
> > > systems.
> > > 
> > > Feedback welcome.
> > > 
> > > Regards,
> > > Lucas
> > > 
> > > Lucas Stach (3):
> > >   PCI: designware: only register MSI controller when MSI irq line
> > > is
> > >     valid
> > >   PCI: imx6: allow MSI irq to be absent
> > >   ARM: dts: imx6qdl: remove MSI irq line
> > > 
> > >  .../devicetree/bindings/pci/fsl,imx6q-pcie.txt     |  8 ++++----
> > >  arch/arm/boot/dts/imx6qdl.dtsi                     |  2 --
> > >  drivers/pci/dwc/pci-imx6.c                         | 23
> > > +++++++++++-----------
> > >  drivers/pci/dwc/pcie-designware-host.c             |  4 ++--
> > >  4 files changed, 17 insertions(+), 20 deletions(-)
> > > 
> > 
> > Lucas,
> > 
> > Thank you for following up on this!
> > 
> > I tested it with and without the third patch that removes msi from
> > the
> > dt thus with both an ath9k 802.11 device which only supports legacy
> > interrupts and a Marvell sky2 device which supports msi as well as
> > legacy interrupts and it works as expected:
> >  - without msi enabled in dts (default): both sky2 and ath9k work
> >  - with msi enabled in dt: sky2 works ath9k does not
> > 
> > Tested-by: Tim Harvey <tharvey at gateworks.com>
> 
> Any comments about this series?

Bjorn already commented on the series and I'm trying free up a slot to
address the feedback.

Regards,
Lucas