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FAILED: patch "[PATCH] cxl/port: Scan single-target ports for decoders" failed to apply to 6.2-stable tree

PATCH [email protected] 1 participant 1 message May 6, 2023

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The patch below does not apply to the 6.2-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.2.y
git checkout FETCH_HEAD
git cherry-pick -x 7bba261e0aa6e8e5f28a3a3def8338b6512534ee
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2023050607-rift-backache-eb84@gregkh' --subject-prefix 'PATCH 6.2.y' HEAD^..

Possible dependencies:

7bba261e0aa6 ("cxl/port: Scan single-target ports for decoders") a5fcd228ca1d ("Merge branch 'for-6.3/cxl-rr-emu' into cxl/next")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 7bba261e0aa6e8e5f28a3a3def8338b6512534ee Mon Sep 17 00:00:00 2001
From: Dan Williams <[email protected]>
Date: Fri, 14 Apr 2023 11:54:11 -0700
Subject: [PATCH] cxl/port: Scan single-target ports for decoders

Do not assume that a single-target port falls back to a passthrough decoder configuration. Scan for decoders and only fallback after probing that the HDM decoder capability is not present.

One user visible affect of this bug is the inability to enumerate present CXL regions as the decoder settings for the present decoders are skipped.

Fixes d17d0540a0db ("cxl/core/hdm: Add CXL standard decoder enumeration to the core")
Reported-by Jonathan Cameron <[email protected]>
Link http://lore.kernel.org/r/[email protected] open here
Cc <[email protected]>
Reviewed-by Jonathan Cameron <[email protected]>
Reviewed-by Dave Jiang <[email protected]>
Reviewed-by Alison Schofield <[email protected]>
Link https://lore.kernel.org/r/168149845130.792294.3210421233937427962.stgit@dwillia2-xfh.jf.intel.com open here
Signed-off-by Dan Williams <[email protected]>
drivers/cxl/core/hdm.c +3 -2
index 6fdf7981ddc7..abe3877cfa63 100644
@@ -92,8 +92,9 @@ static int map_hdm_decoder_regs(struct cxl_port *port, void __iomem *crb,
 
 	cxl_probe_component_regs(&port->dev, crb, &map.component_map);
 	if (!map.component_map.hdm_decoder.valid) {
-		dev_err(&port->dev, "HDM decoder registers invalid\n");
-		return -ENXIO;
+		dev_dbg(&port->dev, "HDM decoder registers not implemented\n");
+		/* unique error code to indicate no HDM decoder capability */
+		return -ENODEV;
 	}
 
 	return cxl_map_component_regs(&port->dev, regs, &map,
drivers/cxl/port.c +13 -5
index 22a7ab2bae7c..eb57324c4ad4 100644
@@ -66,14 +66,22 @@ static int cxl_switch_port_probe(struct cxl_port *port)
 	if (rc < 0)
 		return rc;
 
-	if (rc == 1)
-		return devm_cxl_add_passthrough_decoder(port);
-
 	cxlhdm = devm_cxl_setup_hdm(port, NULL);
-	if (IS_ERR(cxlhdm))
+	if (!IS_ERR(cxlhdm))
+		return devm_cxl_enumerate_decoders(cxlhdm, NULL);
+
+	if (PTR_ERR(cxlhdm) != -ENODEV) {
+		dev_err(&port->dev, "Failed to map HDM decoder capability\n");
 		return PTR_ERR(cxlhdm);
+	}
+
+	if (rc == 1) {
+		dev_dbg(&port->dev, "Fallback to passthrough decoder\n");
+		return devm_cxl_add_passthrough_decoder(port);
+	}
 
-	return devm_cxl_enumerate_decoders(cxlhdm, NULL);
+	dev_err(&port->dev, "HDM decoder capability not found\n");
+	return -ENXIO;
 }
 
 static int cxl_endpoint_port_probe(struct cxl_port *port)