[PATCH] cxl/pci: Honor -EPROBE_DEFER from component register setup

[PATCH] cxl/pci: Honor -EPROBE_DEFER from component register setup

[Dave Jiang]

cxl_pci_setup_regs() for CXL_REGLOC_RBI_COMPONENT can return
-EPROBE_DEFER on a Restricted CXL Host (RCD) when the upstream port
has not yet been enumerated and the Component Registers must be
extracted from the RCRB. cxl_pci_probe() treats every non-zero return
from that call as the benign "component registers not found" case,
logs a warning, and continues. The rc is then immediately overwritten
by the subsequent cxl_pci_type3_init_mailbox() call, so the deferral
is silently swallowed.

Return -EPROBE_DEFER instead of continuing so the probe is retried
once the upstream port is available.

Reported-by: sashiko-bot@kernel.org
Closes: https://lore.kernel.org/linux-cxl/ajzhsubot_PSYtHQ@MWDK4CY14F/T/#m063bbf76b1c9c293ade52ab311018ae6bba11a44
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
 drivers/cxl/pci.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
index 267c679b0b3c..c85aa790ff6e 100644
--- a/drivers/cxl/pci.c
+++ b/drivers/cxl/pci.c
@@ -826,9 +826,13 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	/*
 	 * If the component registers can't be found, the cxl_pci driver may
 	 * still be useful for management functions so don't return an error.
+	 * A deferral request must still be honored, otherwise the component
+	 * and RAS registers are never mapped for the life of the binding.
 	 */
 	rc = cxl_pci_setup_regs(pdev, CXL_REGLOC_RBI_COMPONENT,
 				&cxlds->reg_map);
+	if (rc == -EPROBE_DEFER)
+		return rc;
 	if (rc)
 		dev_warn(&pdev->dev, "No component registers (%d)\n", rc);
 	else if (!cxlds->reg_map.component_map.ras.valid)

base-commit: 8cdeaa50eae8dad34885515f62559ee83e7e8dda
-- 
2.54.0

Re: [PATCH] cxl/pci: Honor -EPROBE_DEFER from component register setup

[Dave Jiang]

Please ignore. Sent wrong version. 

On 7/6/26 3:30 PM, Dave Jiang wrote:
> cxl_pci_setup_regs() for CXL_REGLOC_RBI_COMPONENT can return
> -EPROBE_DEFER on a Restricted CXL Host (RCD) when the upstream port
> has not yet been enumerated and the Component Registers must be
> extracted from the RCRB. cxl_pci_probe() treats every non-zero return
> from that call as the benign "component registers not found" case,
> logs a warning, and continues. The rc is then immediately overwritten
> by the subsequent cxl_pci_type3_init_mailbox() call, so the deferral
> is silently swallowed.
> 
> Return -EPROBE_DEFER instead of continuing so the probe is retried
> once the upstream port is available.
> 
> Reported-by: sashiko-bot@kernel.org
> Closes: https://lore.kernel.org/linux-cxl/ajzhsubot_PSYtHQ@MWDK4CY14F/T/#m063bbf76b1c9c293ade52ab311018ae6bba11a44
> Assisted-by: Claude:claude-opus-4-8
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> ---
>  drivers/cxl/pci.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> index 267c679b0b3c..c85aa790ff6e 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -826,9 +826,13 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>  	/*
>  	 * If the component registers can't be found, the cxl_pci driver may
>  	 * still be useful for management functions so don't return an error.
> +	 * A deferral request must still be honored, otherwise the component
> +	 * and RAS registers are never mapped for the life of the binding.
>  	 */
>  	rc = cxl_pci_setup_regs(pdev, CXL_REGLOC_RBI_COMPONENT,
>  				&cxlds->reg_map);
> +	if (rc == -EPROBE_DEFER)
> +		return rc;
>  	if (rc)
>  		dev_warn(&pdev->dev, "No component registers (%d)\n", rc);
>  	else if (!cxlds->reg_map.component_map.ras.valid)
> 
> base-commit: 8cdeaa50eae8dad34885515f62559ee83e7e8dda