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

[Hongxing Zhu]

> -----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>

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