linux-kernel - [PATCH] fpga: dfl: afu: update initialization of port

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Date: Mon, 22 Jan 2024 09:24:33 -0800
From: Matthew Gerlach <matthew.gerlach@...ux.intel.com>
To: hao.wu@...el.com,
	trix@...hat.com,
	mdf@...nel.org,
	yilun.xu@...el.com,
	linux-fpga@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Matthew Gerlach <matthew.gerlach@...ux.intel.com>
Subject: [PATCH] fpga: dfl: afu: update initialization of port_hdr driver

Revision 2 of the Device Feature List (DFL) Port feature has
slightly different requirements than revision 1. Revision 2
does not need the port to reset at driver startup. In fact,
performing a port reset during driver initialization can cause
driver race conditions when the port is connected to a different
PCIe Physical Function (PF) than the management PF performing
the actual port reset.

Signed-off-by: Matthew Gerlach <matthew.gerlach@...ux.intel.com>
---
 drivers/fpga/dfl-afu-main.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/fpga/dfl-afu-main.c b/drivers/fpga/dfl-afu-main.c
index c0a75ca360d6..7d7f80cd264f 100644
--- a/drivers/fpga/dfl-afu-main.c
+++ b/drivers/fpga/dfl-afu-main.c
@@ -417,7 +417,18 @@ static const struct attribute_group port_hdr_group = {
 static int port_hdr_init(struct platform_device *pdev,
 			 struct dfl_feature *feature)
 {
-	port_reset(pdev);
+	void __iomem *base;
+	u8 rev;
+
+	base = dfl_get_feature_ioaddr_by_id(&pdev->dev, PORT_FEATURE_ID_HEADER);
+
+	rev = dfl_feature_revision(base);
+
+	if (rev < 2)
+		port_reset(pdev);
+
+	if (rev > 2)
+		dev_info(&pdev->dev, "unexpected port feature revision, %u\n", rev);
 
 	return 0;
 }
-- 
2.34.1