linux-kernel - [PATCH v2 4/4] PCI: Use an error code with PCIe failed link retraining

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Message-ID: <alpine.DEB.2.21.2408091156530.61955@angie.orcam.me.uk>
Date: Fri, 9 Aug 2024 14:25:02 +0100 (BST)
From: "Maciej W. Rozycki" <macro@...am.me.uk>
To: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>, 
    Matthew W Carlis <mattc@...estorage.com>, 
    Bjorn Helgaas <bhelgaas@...gle.com>
cc: Mika Westerberg <mika.westerberg@...ux.intel.com>, 
    Oliver O'Halloran <oohall@...il.com>, linux-pci@...r.kernel.org, 
    linux-kernel@...r.kernel.org
Subject: [PATCH v2 4/4] PCI: Use an error code with PCIe failed link
 retraining

Given how the call place in `pcie_wait_for_link_delay' got structured 
now, and that `pcie_retrain_link' returns a potentially useful error 
code, convert `pcie_failed_link_retrain' to return an error code rather 
than a boolean status, fixing handling at the call site mentioned.  
Update the other call site accordingly.

Fixes: 1abb47390350 ("Merge branch 'pci/enumeration'")
Reported-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Link: https://lore.kernel.org/r/aa2d1c4e-9961-d54a-00c7-ddf8e858a9b0@linux.intel.com/
Signed-off-by: Maciej W. Rozycki <macro@...am.me.uk>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Cc: stable@...r.kernel.org # v6.5+
---
Changes from v1 (superseding 2/2):

- Regenerate following changes to 3/4, no functional change.
---
 drivers/pci/pci.c    |    2 +-
 drivers/pci/pci.h    |    6 +++---
 drivers/pci/quirks.c |   20 ++++++++++----------
 3 files changed, 14 insertions(+), 14 deletions(-)

linux-pcie-failed-link-retrain-status-int.diff
Index: linux-macro/drivers/pci/pci.c
===================================================================
--- linux-macro.orig/drivers/pci/pci.c
+++ linux-macro/drivers/pci/pci.c
@@ -1324,7 +1324,7 @@ static int pci_dev_wait(struct pci_dev *
 		if (delay > PCI_RESET_WAIT) {
 			if (retrain) {
 				retrain = false;
-				if (pcie_failed_link_retrain(bridge)) {
+				if (pcie_failed_link_retrain(bridge) == 0) {
 					delay = 1;
 					continue;
 				}
Index: linux-macro/drivers/pci/pci.h
===================================================================
--- linux-macro.orig/drivers/pci/pci.h
+++ linux-macro/drivers/pci/pci.h
@@ -606,7 +606,7 @@ void pci_acs_init(struct pci_dev *dev);
 int pci_dev_specific_acs_enabled(struct pci_dev *dev, u16 acs_flags);
 int pci_dev_specific_enable_acs(struct pci_dev *dev);
 int pci_dev_specific_disable_acs_redir(struct pci_dev *dev);
-bool pcie_failed_link_retrain(struct pci_dev *dev);
+int pcie_failed_link_retrain(struct pci_dev *dev);
 #else
 static inline int pci_dev_specific_acs_enabled(struct pci_dev *dev,
 					       u16 acs_flags)
@@ -621,9 +621,9 @@ static inline int pci_dev_specific_disab
 {
 	return -ENOTTY;
 }
-static inline bool pcie_failed_link_retrain(struct pci_dev *dev)
+static inline int pcie_failed_link_retrain(struct pci_dev *dev)
 {
-	return false;
+	return -ENOTTY;
 }
 #endif
 
Index: linux-macro/drivers/pci/quirks.c
===================================================================
--- linux-macro.orig/drivers/pci/quirks.c
+++ linux-macro/drivers/pci/quirks.c
@@ -78,21 +78,21 @@
  * again to remove any residual state, ignoring the result as it's supposed
  * to fail anyway.
  *
- * Return TRUE if the link has been successfully retrained.  Return FALSE
+ * Return 0 if the link has been successfully retrained.  Return an error
  * if retraining was not needed or we attempted a retrain and it failed.
  */
-bool pcie_failed_link_retrain(struct pci_dev *dev)
+int pcie_failed_link_retrain(struct pci_dev *dev)
 {
 	static const struct pci_device_id ids[] = {
 		{ PCI_VDEVICE(ASMEDIA, 0x2824) }, /* ASMedia ASM2824 */
 		{}
 	};
 	u16 lnksta, lnkctl2;
-	bool ret = false;
+	int ret = -ENOTTY;
 
 	if (!pci_is_pcie(dev) || !pcie_downstream_port(dev) ||
 	    !pcie_cap_has_lnkctl2(dev) || !dev->link_active_reporting)
-		return false;
+		return ret;
 
 	pcie_capability_read_word(dev, PCI_EXP_LNKCTL2, &lnkctl2);
 	pcie_capability_read_word(dev, PCI_EXP_LNKSTA, &lnksta);
@@ -106,13 +106,13 @@ bool pcie_failed_link_retrain(struct pci
 		lnkctl2 |= PCI_EXP_LNKCTL2_TLS_2_5GT;
 		pcie_capability_write_word(dev, PCI_EXP_LNKCTL2, lnkctl2);
 
-		ret = pcie_retrain_link(dev, false) == 0;
-		if (!ret) {
+		ret = pcie_retrain_link(dev, false);
+		if (ret) {
 			pci_info(dev, "retraining failed\n");
 			pcie_capability_write_word(dev, PCI_EXP_LNKCTL2,
 						   oldlnkctl2);
 			pcie_retrain_link(dev, false);
-			return false;
+			return ret;
 		}
 
 		pcie_capability_read_word(dev, PCI_EXP_LNKSTA, &lnksta);
@@ -129,10 +129,10 @@ bool pcie_failed_link_retrain(struct pci
 		lnkctl2 |= lnkcap & PCI_EXP_LNKCAP_SLS;
 		pcie_capability_write_word(dev, PCI_EXP_LNKCTL2, lnkctl2);
 
-		ret = pcie_retrain_link(dev, false) == 0;
-		if (!ret) {
+		ret = pcie_retrain_link(dev, false);
+		if (ret) {
 			pci_info(dev, "retraining failed\n");
-			return false;
+			return ret;
 		}
 	}