Re: [PATCH v2] PCI: quirks: Add warm reset quirk for IBM Spyre accelerator

[Mahesh J Salgaonkar <mahesh@linux.ibm.com>]

On 2026-08-21 18:04:01 Fri, Avinash Roy wrote:
> From: Shivaprasad G Bhat <sbhat@linux.ibm.com>
> 
> The IBM Spyre accelerator (PCI ID 1014:06a7) requires a dedicated warm
> reset method for reliable EEH recovery on pSeries/ppc64 platforms.
> 
> FLR alone is insufficient because it does not re-initialize firmware
> state machine for the current version of the card. The existing API
> pci_set_pcie_reset_state() is used to drive the platform-level
> PERST# using the EEH interfaces by adding a device specific quirk.
> 
> The reset function is placed in arch/powerpc/platforms/pseries/pci.c
> where the EEH infrastructure is already present, declared in
> pseries.h, and registered in the generic pci_dev_reset_methods[] table
> in drivers/pci/quirks.c under a CONFIG_PPC_PSERIES guard.
> 
> This reset method is only registered when CONFIG_PPC_PSERIES is enabled,
> so it is not available on other platforms.
> 
> Reset sequence:
>   - Assert PERST# via pcie_warm_reset, hold 250 ms
>   - Deassert PERST# via pcie_deassert_reset
>   - Wait 250 ms for PCIe link retrain 	
> 
> Signed-off-by: Avinash Roy <avinash.roy1@linux.ibm.com>
> Signed-off-by: Shivaprasad G Bhat <sbhat@linux.ibm.com>
> 
> ---
> Changelog
> v1: https://lore.kernel.org/linux-pci/20260805125100.1-1-avinash.roy1@linux.ibm.com/
> 
>    Reworded the commit message to highlight the warm reset requirement being
>    a need of the current card and not a platform deficiency.
> 
> diff --git a/arch/powerpc/platforms/pseries/pci.c b/arch/powerpc/platforms/pseries/pci.c
> index 84e4ffe957a8..7aa58d57208f 100644
> --- a/arch/powerpc/platforms/pseries/pci.c
> +++ b/arch/powerpc/platforms/pseries/pci.c
> @@ -11,6 +11,7 @@
>  #include <linux/kernel.h>
>  #include <linux/pci.h>
>  #include <linux/string.h>
> +#include <linux/delay.h>
>  
>  #include <asm/eeh.h>
>  #include <asm/pci-bridge.h>
> @@ -236,6 +237,41 @@ static void fixup_winbond_82c105(struct pci_dev* dev)
>  DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_WINBOND, PCI_DEVICE_ID_WINBOND_82C105,
>  			 fixup_winbond_82c105);
>  
> +/*
> + * Reset Spyre adapter using pci_set_pcie_reset_state()
> + * This is specifically for PPC platforms where EEH (Enhanced Error Handling)
> + * requires this reset method for proper device recovery.
> + */
> +int reset_spyre(struct pci_dev *dev, bool probe)
> +{
> +	int ret;
> +
> +	if (probe)
> +		return 0;
> +
> +	/* Assert warm reset */
> +	ret = pci_set_pcie_reset_state(dev, pcie_warm_reset);
> +	if (ret) {
> +		pci_err(dev, "Failed to assert reset: %d\n", ret);
> +		return ret;
> +	}
> +
> +	/* Wait for reset to take effect */
> +	msleep(250);

How did you arriver on this number ? Is this time defined by
hardware/firmware specs for reset ?  Also, Can you #define the value 250
and use macro instead of constant numbmer.

> +
> +	/* Deassert reset */
> +	ret = pci_set_pcie_reset_state(dev, pcie_deassert_reset);
> +	if (ret) {
> +		pci_err(dev, "Failed to deassert reset: %d\n", ret);
> +		return ret;
> +	}
> +
> +	/* Wait for device to recover */
> +	msleep(250);

same here.

> +
> +	return 0;
> +}
> +

Thanks,
-Mahesh.