linux-kernel - [PATCH v9 5/9] PCI/quirks: Abstract LBMS seen check into own function

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Message-Id: <20241018144755.7875-6-ilpo.jarvinen@linux.intel.com>
Date: Fri, 18 Oct 2024 17:47:51 +0300
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: linux-pci@...r.kernel.org,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Wilczyński <kw@...ux.com>,
	"Maciej W . Rozycki" <macro@...am.me.uk>,
	Jonathan Cameron <Jonathan.Cameron@...wei.com>,
	Lukas Wunner <lukas@...ner.de>,
	Alexandru Gagniuc <mr.nuke.me@...il.com>,
	Krishna chaitanya chundru <quic_krichai@...cinc.com>,
	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
	"Rafael J . Wysocki" <rafael@...nel.org>,
	linux-pm@...r.kernel.org,
	Smita Koralahalli <Smita.KoralahalliChannabasappa@....com>,
	linux-kernel@...r.kernel.org
Cc: Daniel Lezcano <daniel.lezcano@...aro.org>,
	Amit Kucheria <amitk@...nel.org>,
	Zhang Rui <rui.zhang@...el.com>,
	Christophe JAILLET <christophe.jaillet@...adoo.fr>,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
	Jonathan Cameron <Jonathan.Cameron@...wei.com>
Subject: [PATCH v9 5/9] PCI/quirks: Abstract LBMS seen check into own function

The Target Speed quirk in pcie_failed_link_retrain() uses the presence
of LBMS bit as one of the triggering conditions effectively
monopolizing the use of that bit. An upcoming change will introduce a
PCIe bandwidth controller which sets up an interrupt to track LBMS. As
LBMS will be cleared by the interrupt handler, the Target Speed quirk
will no longer be able to observe LBMS directly.

As a preparatory step for the change, extract the LBMS seen check from
pcie_failed_link_retrain() into a new function pcie_lmbs_seen().

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
---
 drivers/pci/quirks.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index dccb60c1d9cc..a560ea403b8e 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -33,6 +33,11 @@
 #include <linux/switchtec.h>
 #include "pci.h"
 
+static bool pcie_lbms_seen(struct pci_dev *dev, u16 lnksta)
+{
+	return lnksta & PCI_EXP_LNKSTA_LBMS;
+}
+
 /*
  * Retrain the link of a downstream PCIe port by hand if necessary.
  *
@@ -96,8 +101,7 @@ int pcie_failed_link_retrain(struct pci_dev *dev)
 
 	pcie_capability_read_word(dev, PCI_EXP_LNKCTL2, &lnkctl2);
 	pcie_capability_read_word(dev, PCI_EXP_LNKSTA, &lnksta);
-	if ((lnksta & (PCI_EXP_LNKSTA_LBMS | PCI_EXP_LNKSTA_DLLLA)) ==
-	    PCI_EXP_LNKSTA_LBMS) {
+	if (!(lnksta & PCI_EXP_LNKSTA_DLLLA) && pcie_lbms_seen(dev, lnksta)) {
 		u16 oldlnkctl2 = lnkctl2;
 
 		pci_info(dev, "broken device, retraining non-functional downstream link at 2.5GT/s\n");
-- 
2.39.5