RE: [PATCH] PCI: imx6: Keep Root Port MSI capability also for i.MX6Q

[Hongxing Zhu]

> -----Original Message-----
> From: Soeren Moch <smoch@xxxxxx>
> Sent: Sunday, July 5, 2026 5:11 PM
> To: Hongxing Zhu <hongxing.zhu@xxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx; Manivannan Sadhasivam <mani@xxxxxxxxxx>; Lucas
> Stach <l.stach@xxxxxxxxxxxxxx>; Bjorn Helgaas <bhelgaas@xxxxxxxxxx>; Frank
> Li <frank.li@xxxxxxx>; Fabio Estevam <festevam@xxxxxxxxx>; linux-
> pci@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; imx@xxxxxxxxxxxxxxx;
> linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH] PCI: imx6: Keep Root Port MSI capability also for i.MX6Q
> 
> [You don't often get email from smoch@xxxxxx. Learn why this is important at
> https://aka.ms/LearnAboutSenderIdentification ]
> 
> On 28.04.26 04:19, Hongxing Zhu wrote:
> >> -----Original Message-----
> >> From: Soeren Moch <smoch@xxxxxx>
> >> Sent: Monday, April 27, 2026 7:58 PM
> >> To: Hongxing Zhu <hongxing.zhu@xxxxxxx>
> >> Cc: Soeren Moch <smoch@xxxxxx>; stable@xxxxxxxxxxxxxxx; Manivannan
> >> Sadhasivam <mani@xxxxxxxxxx>; Lucas Stach <l.stach@xxxxxxxxxxxxxx>;
> >> Bjorn Helgaas <bhelgaas@xxxxxxxxxx>; Frank Li <frank.li@xxxxxxx>;
> >> Fabio Estevam <festevam@xxxxxxxxx>; linux-pci@xxxxxxxxxxxxxxx;
> >> linux-arm- kernel@xxxxxxxxxxxxxxxxxxx; imx@xxxxxxxxxxxxxxx;
> >> linux-kernel@xxxxxxxxxxxxxxx
> >> Subject: [PATCH] PCI: imx6: Keep Root Port MSI capability also for
> >> i.MX6Q
> >>
> >> [You don't often get email from smoch@xxxxxx. Learn why this is
> >> important at https://aka.ms/LearnAboutSenderIdentification ]
> >>
> >> Also on the NXP i.MX6Q chipset MSIs from the endpoints won't be
> >> received by the iMSI-RX MSI controller if the Root Port MSI capability is
> disabled.
> >>
> >> Even though the Root Port MSIs won't be received by the iMSI-RX
> >> controller due to design, this chipset has some weird hardware bug
> >> that prevents the endpoint MSIs from reaching when the Root Port MSI
> capability is disabled.
> >>
> >> Hence, always keep the Root Port MSI capability for this chipset.
> >>
> >> Note that by keeping Root Port MSI capability, Root Port MSIs such as
> >> AER, PME and others won't be received by default. So users need to
> >> use workarounds such as passing 'pcie_pme=nomsi' cmdline param.
> >>
> >> Fixes: 3a4e8302e72f ("PCI: imx6: Keep Root Port MSI capability with
> >> iMSI-RX to work around hardware bug")
> >> Cc: <stable@xxxxxxxxxxxxxxx> # 7.0.x
> >> Signed-off-by: Soeren Moch <smoch@xxxxxx>
> > Acked-by: Richard Zhu <hongxing.zhu@xxxxxxx>
> 
> This patch is a regression fix for linux-7.0.
> It is still not part of linux-7.2-rc1 .
> 
> Can I do something to get this merged, is something still missing from my side?
Maybe Mani missed this fix in previous merge window.
Hi Mani:
Can you help to take look at this minor fix patch?

Best Regards
Richard Zhu
> 
> Thanks,
> Soeren
> 
> >
> > Best Regards
> > Richard Zhu
> >> ---
> >> Cc: Manivannan Sadhasivam <mani@xxxxxxxxxx>
> >> Cc: Richard Zhu <hongxing.zhu@xxxxxxx>
> >> Cc: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
> >> Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> >> Cc: Frank Li <Frank.Li@xxxxxxx>
> >> Cc: Fabio Estevam <festevam@xxxxxxxxx>
> >> Cc: linux-pci@xxxxxxxxxxxxxxx
> >> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> >> Cc: imx@xxxxxxxxxxxxxxx
> >> Cc: linux-kernel@xxxxxxxxxxxxxxx
> >>
> >> Tested on a tbs2910 board [1]
> >> [1] arch/arm/boot/dts/nxp/imx/imx6q-tbs2910.dts
> >> ---
> >>   drivers/pci/controller/dwc/pci-imx6.c | 3 ++-
> >>   1 file changed, 2 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/pci/controller/dwc/pci-imx6.c
> >> b/drivers/pci/controller/dwc/pci-imx6.c
> >> index 6d6a1688e7eb..3d461bdef967 100644
> >> --- a/drivers/pci/controller/dwc/pci-imx6.c
> >> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> >> @@ -1865,7 +1865,8 @@ static const struct imx_pcie_drvdata drvdata[] = {
> >>                  .flags = IMX_PCIE_FLAG_IMX_PHY |
> >>                           IMX_PCIE_FLAG_SPEED_CHANGE_WORKAROUND |
> >>                           IMX_PCIE_FLAG_BROKEN_SUSPEND |
> >> -                        IMX_PCIE_FLAG_SUPPORTS_SUSPEND,
> >> +                        IMX_PCIE_FLAG_SUPPORTS_SUSPEND |
> >> +                        IMX_PCIE_FLAG_KEEP_MSI_CAP,
> >>                  .dbi_length = 0x200,
> >>                  .gpr = "fsl,imx6q-iomuxc-gpr",
> >>                  .ltssm_off = IOMUXC_GPR12,
> >> --
> >> 2.43.0
> >