imx: coretexa53: add PCIe fixes

update kernel with two patches to address PCIe link issues: - 312-PCI-imx6-Start-link-at-max-speed-first.patch Address link issues with QCA988X endpoints through PI7C9X2G608GP switch used on GW73xx-A/B/F+ board revisions - 313-PCI-imx6-de-duplicate-Link-up-message.patch de-dupliate PCIe link up messages Signed-off-by: Tim Harvey <[email protected]>
Gateworks · Dec 21, 2023 · f507da6 · f507da6
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diff --git a/target/linux/imx/patches-5.15/312-PCI-imx6-Start-link-at-max-speed-first.patch b/target/linux/imx/patches-5.15/312-PCI-imx6-Start-link-at-max-speed-first.patch
@@ -0,0 +1,96 @@
+From 1c0c14baea296354791ebf6371f2f7331549bfde Mon Sep 17 00:00:00 2001
+From: Tim Harvey <[email protected]>
+Date: Fri, 18 Aug 2023 19:34:54 -0700
+Subject: [PATCH 1/2] PCI: imx6: Start link at max speed first
+
+commit fa33a6d87eac ("PCI: imx6: Start link in Gen1 before negotiating
+for Gen2 mode") started link negotiation at Gen1 before attempting
+faster speeds in order to work around an issue with a particular switch
+on an IMX6Q SoC.
+
+Restore this behavior to the PCI standard of linking at the max speed
+first before a downgrade. This resolves a high rate of link failures
+with certain endpoints (QCA988x) when using a PCIe switch.
+
+Signed-off-by: Tim Harvey <[email protected]>
+---
+ drivers/pci/controller/dwc/pci-imx6.c | 60 ++++-----------------------
+ 1 file changed, 7 insertions(+), 53 deletions(-)
+
+diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
+index 349a6daea5e8..6cea06688a81 100644
+--- a/drivers/pci/controller/dwc/pci-imx6.c
++++ b/drivers/pci/controller/dwc/pci-imx6.c
+@@ -797,62 +797,16 @@ static int imx6_pcie_start_link(struct dw_pcie *pci)
+ 	u32 tmp;
+ 	int ret;
+
+-	/*
+-	 * Force Gen1 operation when starting the link.  In case the link is
+-	 * started in Gen2 mode, there is a possibility the devices on the
+-	 * bus will not be detected at all.  This happens with PCIe switches.
+-	 */
+-	tmp = dw_pcie_readl_dbi(pci, offset + PCI_EXP_LNKCAP);
+-	tmp &= ~PCI_EXP_LNKCAP_SLS;
+-	tmp |= PCI_EXP_LNKCAP_SLS_2_5GB;
+-	dw_pcie_writel_dbi(pci, offset + PCI_EXP_LNKCAP, tmp);
+-
+ 	/* Start LTSSM. */
+ 	imx6_pcie_ltssm_enable(dev);
+-
+-	dw_pcie_wait_for_link(pci);
+-
+-	if (pci->link_gen == 2) {
+-		/* Allow Gen2 mode after the link is up. */
+-		tmp = dw_pcie_readl_dbi(pci, offset + PCI_EXP_LNKCAP);
+-		tmp &= ~PCI_EXP_LNKCAP_SLS;
+-		tmp |= PCI_EXP_LNKCAP_SLS_5_0GB;
+-		dw_pcie_writel_dbi(pci, offset + PCI_EXP_LNKCAP, tmp);
+-
+-		/*
+-		 * Start Directed Speed Change so the best possible
+-		 * speed both link partners support can be negotiated.
+-		 */
+-		tmp = dw_pcie_readl_dbi(pci, PCIE_LINK_WIDTH_SPEED_CONTROL);
+-		tmp |= PORT_LOGIC_SPEED_CHANGE;
+-		dw_pcie_writel_dbi(pci, PCIE_LINK_WIDTH_SPEED_CONTROL, tmp);
+-
+-		if (imx6_pcie->drvdata->flags &
+-		    IMX6_PCIE_FLAG_IMX6_SPEED_CHANGE) {
+-			/*
+-			 * On i.MX7, DIRECT_SPEED_CHANGE behaves differently
+-			 * from i.MX6 family when no link speed transition
+-			 * occurs and we go Gen1 -> yep, Gen1. The difference
+-			 * is that, in such case, it will not be cleared by HW
+-			 * which will cause the following code to report false
+-			 * failure.
+-			 */
+-
+-			ret = imx6_pcie_wait_for_speed_change(imx6_pcie);
+-			if (ret) {
+-				dev_err(dev, "Failed to bring link up!\n");
+-				goto err_reset_phy;
+-			}
+-		}
+-
+-		/* Make sure link training is finished as well! */
+-		dw_pcie_wait_for_link(pci);
+-	} else {
+-		dev_info(dev, "Link: Gen2 disabled\n");
+-	}
+-
++	ret = dw_pcie_wait_for_link(pci);
++	if (ret)
++		goto err_reset_phy;
+ 	tmp = dw_pcie_readw_dbi(pci, offset + PCI_EXP_LNKSTA);
+-	dev_info(dev, "Link up, Gen%i\n", tmp & PCI_EXP_LNKSTA_CLS);
++	dev_info(pci->dev, "PCIe Gen.%u x%u link up\n",
++		FIELD_GET(PCI_EXP_LNKSTA_CLS, tmp),
++		FIELD_GET(PCI_EXP_LNKSTA_NLW, tmp));
++
+ 	return 0;
+
+ err_reset_phy:
+-- 
+2.25.1
+
diff --git a/target/linux/imx/patches-5.15/313-PCI-imx6-de-duplicate-Link-up-message.patch b/target/linux/imx/patches-5.15/313-PCI-imx6-de-duplicate-Link-up-message.patch
@@ -0,0 +1,45 @@
+From 13663a09dface74817d17f1a96135d9b85a0f23d Mon Sep 17 00:00:00 2001
+From: Tim Harvey <[email protected]>
+Date: Thu, 21 Dec 2023 11:08:05 -0800
+Subject: [PATCH 2/2] PCI: imx6: de-duplicate Link up message
+
+remove the link up message from dw_pcie_wait_for_link as it is already
+shown with more detail in imx6_pcie_start_link
+
+Signed-off-by: Tim Harvey <[email protected]>
+---
+ drivers/pci/controller/dwc/pcie-designware.c | 14 ++++++++------
+ 1 file changed, 8 insertions(+), 6 deletions(-)
+
+diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
+index 00972a7bc976..237c2f5df00a 100644
+--- a/drivers/pci/controller/dwc/pcie-designware.c
++++ b/drivers/pci/controller/dwc/pcie-designware.c
+@@ -528,16 +528,18 @@ int dw_pcie_wait_for_link(struct dw_pcie *pci)
+
+ 	/* Check if the link is up or not */
+ 	for (retries = 0; retries < LINK_WAIT_MAX_RETRIES; retries++) {
+-		if (dw_pcie_link_up(pci)) {
+-			dev_info(pci->dev, "Link up\n");
+-			return 0;
+-		}
++		if (dw_pcie_link_up(pci))
++			break;
++
+ 		usleep_range(LINK_WAIT_USLEEP_MIN, LINK_WAIT_USLEEP_MAX);
+ 	}
+
+-	dev_info(pci->dev, "Phy link never came up\n");
++	if (retries >= LINK_WAIT_MAX_RETRIES) {
++		dev_info(pci->dev, "Phy link never came up\n");
++		return -ETIMEDOUT;
++	}
+
+-	return -ETIMEDOUT;
++	return 0;
+ }
+ EXPORT_SYMBOL_GPL(dw_pcie_wait_for_link);
+
+-- 
+2.25.1
+