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From:   Artem Lapkin <email2tema@gmail.com>
To:     narmstrong@baylibre.com
Cc:     yue.wang@Amlogic.com, khilman@baylibre.com,
        lorenzo.pieralisi@arm.com, robh@kernel.org, kw@linux.com,
        jbrunet@baylibre.com, christianshewitt@gmail.com,
        martin.blumenstingl@googlemail.com, linux-pci@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-amlogic@lists.infradead.org, linux-kernel@vger.kernel.org,
        art@khadas.com, nick@khadas.com, gouwa@khadas.com
Subject: [PATCH] PCI: dwc: meson add quirk
Date:   Fri, 18 Jun 2021 14:38:21 +0800
Message-Id: <20210618063821.1383357-1-art@khadas.com>
MIME-Version: 1.0
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Device set same 256 bytes maximum read request size equal MAX_READ_REQ_SIZE
was find some issue with HDMI scrambled picture and nvme devices
at intensive writing...

[    4.798971] nvme 0000:01:00.0: fix MRRS from 512 to 256

This quirk setup same MRRS if we try solve this problem with
pci=pcie_bus_perf kernel command line param

Signed-off-by: Artem Lapkin <art@khadas.com>
---
 drivers/pci/controller/dwc/pci-meson.c | 27 ++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/drivers/pci/controller/dwc/pci-meson.c b/drivers/pci/controller/dwc/pci-meson.c
index 686ded034f22..e2d40e5c2661 100644
--- a/drivers/pci/controller/dwc/pci-meson.c
+++ b/drivers/pci/controller/dwc/pci-meson.c
@@ -466,6 +466,33 @@ static int meson_pcie_probe(struct platform_device *pdev)
 	return ret;
 }
 
+static void meson_pcie_quirk(struct pci_dev *dev)
+{
+	int mrrs;
+
+	/* no need quirk */
+	if (pcie_bus_config != PCIE_BUS_DEFAULT)
+		return;
+
+	/* no need for root bus */
+	if (pci_is_root_bus(dev->bus))
+		return;
+
+	mrrs = pcie_get_readrq(dev);
+
+	/*
+	 * set same 256 bytes maximum read request size equal MAX_READ_REQ_SIZE
+	 * was find some issue with HDMI scrambled picture and nvme devices
+	 * at intensive writing...
+	 */
+
+	if (mrrs != MAX_READ_REQ_SIZE) {
+		dev_info(&dev->dev, "fix MRRS from %d to %d\n", mrrs, MAX_READ_REQ_SIZE);
+		pcie_set_readrq(dev, MAX_READ_REQ_SIZE);
+	}
+}
+DECLARE_PCI_FIXUP_ENABLE(PCI_ANY_ID, PCI_ANY_ID, meson_pcie_quirk);
+
 static const struct of_device_id meson_pcie_of_match[] = {
 	{
 		.compatible = "amlogic,axg-pcie",
-- 
2.25.1