From: Bean Huo beanhuo@micron.com
As per PCIe r6.2, sec 6.13 titled "Alternative Routing-ID Interpretation (ARI)", up to 8 [fn # 0..7] Physical Functions(PFs) are allowed in an non-ARI capable device. Previously, our implementation erroneously limited the maximum number of PFs to 7 for endpoints without ARI support.
This patch corrects the maximum PF count to adhere to the PCIe specification by allowing up to 8 PFs on non-ARI capable devices. This change ensures better compliance with the standard and improves compatibility with devices relying on this specification.
Fixes: c3df83e01a96 ("PCI: Clean up pci_scan_slot()") Cc: stable@vger.kernel.org Signed-off-by: Bean Huo beanhuo@micron.com --- Changelog: v2--v3: 1. Update commit messag v1--v2: 1. Add Fixes tag 2. Modify commit message --- drivers/pci/probe.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index ed6b7f48736a..8c3d0f63bc13 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -2630,7 +2630,8 @@ static int next_fn(struct pci_bus *bus, struct pci_dev *dev, int fn) if (pci_ari_enabled(bus)) return next_ari_fn(bus, dev, fn);
- if (fn >= 7) + /* If EP does not support ARI, the maximum number of functions should be 7 */ + if (fn > 7) return -ENODEV; /* only multifunction devices may have more functions */ if (dev && !dev->multifunction)
On 24/02/19 12:24PM, Bean Huo wrote:
From: Bean Huo beanhuo@micron.com
As per PCIe r6.2, sec 6.13 titled "Alternative Routing-ID Interpretation (ARI)", up to 8 [fn # 0..7] Physical Functions(PFs) are allowed in an non-ARI capable device. Previously, our implementation erroneously limited the maximum number of PFs to 7 for endpoints without ARI support.
This patch corrects the maximum PF count to adhere to the PCIe specification by allowing up to 8 PFs on non-ARI capable devices. This change ensures better compliance with the standard and improves compatibility with devices relying on this specification.
The function "next_fn()" seems to provide the next valid function. Therefore, if the current function is 0 (fn = 0), then the next valid function will be 1 which is returned by next_fn(). It extends similarly until the case where current function is 6 (fn = 6) which shall return the next valid function as 7. So all 8 PFs are still treated as valid and there doesn't seem to be any limitation. Only in the case where the EP doesn't support ARI (there is no function 8 (fn = 8)), the call to next_fn() with the fn parameter set to 7, will return -ENODEV which seems to be the expected behavior.
Regards, Siddharth.
Fixes: c3df83e01a96 ("PCI: Clean up pci_scan_slot()") Cc: stable@vger.kernel.org Signed-off-by: Bean Huo beanhuo@micron.com
Changelog: v2--v3: 1. Update commit messag v1--v2: 1. Add Fixes tag 2. Modify commit message
drivers/pci/probe.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index ed6b7f48736a..8c3d0f63bc13 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -2630,7 +2630,8 @@ static int next_fn(struct pci_bus *bus, struct pci_dev *dev, int fn) if (pci_ari_enabled(bus)) return next_ari_fn(bus, dev, fn);
- if (fn >= 7)
- /* If EP does not support ARI, the maximum number of functions should be 7 */
- if (fn > 7) return -ENODEV; /* only multifunction devices may have more functions */ if (dev && !dev->multifunction)
-- 2.34.1
On Mon, 2024-02-19 at 17:30 +0530, Siddharth Vadapalli wrote:
The function "next_fn()" seems to provide the next valid function. Therefore, if the current function is 0 (fn = 0), then the next valid function will be 1 which is returned by next_fn(). It extends similarly until the case where current function is 6 (fn = 6) which shall return the next valid function as 7. So all 8 PFs are still treated as valid and there doesn't seem to be any limitation. Only in the case where the EP doesn't support ARI (there is no function 8 (fn = 8)), the call to next_fn() with the fn parameter set to 7, will return -ENODEV which seems to be the expected behavior.
Regards, Siddharth.
yes, you are right, the fn 7 has no next_fn, hence should return - ENODEV.
ignore this patch!
kind regards, Bean
linux-stable-mirror@lists.linaro.org
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Bean Huo -
Siddharth Vadapalli