Re: [PATCH] PCI: Add quirk to clear MSI-X

[Thomas Glanzmann <thomas@glanzmann.de>]

Hello,

* Basavaraj Natikar <Basavaraj.Natikar@amd.com> [2023-03-06 08:24]:
> One of the AMD USB controllers fails to maintain internal functional
> context when transitioning from D3 to D0, desynchronizing MSI-X bits.
> As a result, add a quirk to this controller to clear the MSI-X bits
> on suspend.

> Note: This quirk works in all scenarios, regardless of whether the
> integrated GPU is disabled in the BIOS.

I tested the patch on top of v6.2.2 and USB hotplug works. Dmesg is here:

https://pbot.rmdir.de/H1BcUKbZUQQJ7NB6UylFEQ

> Cc: Mario Limonciello <mario.limonciello@amd.com>
> Reported-by: Thomas Glanzmann <thomas@glanzmann.de>

Tested-by: Thomas Glanzmann <thomas@glanzmann.de>

> Link: https://lore.kernel.org/linux-usb/Y%2Fz9GdHjPyF2rNG3@glanzmann.de/T/#u
> Signed-off-by: Basavaraj Natikar <Basavaraj.Natikar@amd.com>
> ---
>  drivers/pci/quirks.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)

> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index 44cab813bf95..ddf7100227d3 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -6023,3 +6023,13 @@ DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x9a2d, dpc_log_size);
>  DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x9a2f, dpc_log_size);
>  DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x9a31, dpc_log_size);
>  #endif
> +
> +static void quirk_clear_msix(struct pci_dev *dev)
> +{
> +	u16 ctrl;
> +
> +	pci_read_config_word(dev, dev->msix_cap + PCI_MSIX_FLAGS, &ctrl);
> +	ctrl &= ~(PCI_MSIX_FLAGS_MASKALL | PCI_MSIX_FLAGS_ENABLE);
> +	pci_write_config_word(dev, dev->msix_cap + PCI_MSIX_FLAGS, ctrl);
> +}
> +DECLARE_PCI_FIXUP_SUSPEND(PCI_VENDOR_ID_AMD, 0x15b8, quirk_clear_msix);

Thank you for the patch.

Cheers,
        Thomas