linux-kernel - [PATCH] cxl/hdm: dev_warn() on unsupported mixed mode decoder

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Message-Id: <20230218013834.31237-1-alison.schofield@intel.com>
Date:   Fri, 17 Feb 2023 17:38:34 -0800
From:   alison.schofield@...el.com
To:     Dan Williams <dan.j.williams@...el.com>,
        Ira Weiny <ira.weiny@...el.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Ben Widawsky <bwidawsk@...nel.org>
Cc:     Alison Schofield <alison.schofield@...el.com>,
        linux-cxl@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] cxl/hdm: dev_warn() on unsupported mixed mode decoder

From: Alison Schofield <alison.schofield@...el.com>

A mixed mode decoder is programmed with device physical addresses
that span both ram and pmem partitions of a memdev.

Linux does not support mixed mode decoders. The driver rejects
sysfs writes that try to set decoder mode to mixed, and if a
resource bieng allocated is not wholly contained in either the
pmem or ram partition of a memdev, it is also rejected. Basically,
the CXL region driver is not going to create regions with mixed
mode decoders, but the BIOS could.

If the kernel driver sees the mixed mode decoder, it will fail to
enable the region, and emit a dev_dbg() message.

A dev_dbg() is not noisy enough in this case. Change the message
to be a dev_warn() that explicitly says mixed mode is not supported.

Suggested-by: Dan Williams <dan.j.williams@...el.com>
Signed-off-by: Alison Schofield <alison.schofield@...el.com>
---
 drivers/cxl/core/hdm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
index 45deda18ed32..9eaf93c8ebb0 100644
--- a/drivers/cxl/core/hdm.c
+++ b/drivers/cxl/core/hdm.c
@@ -294,8 +294,8 @@ static int __cxl_dpa_reserve(struct cxl_endpoint_decoder *cxled,
 	else if (resource_contains(&cxlds->ram_res, res))
 		cxled->mode = CXL_DECODER_RAM;
 	else {
-		dev_dbg(dev, "decoder%d.%d: %pr mixed\n", port->id,
-			cxled->cxld.id, cxled->dpa_res);
+		dev_warn(dev, "decoder%d.%d: %pr mixed mode not supported\n",
+			 port->id, cxled->cxld.id, cxled->dpa_res);
 		cxled->mode = CXL_DECODER_MIXED;
 	}

base-commit: a5fcd228ca1db9810ba1ed461c90b6ee933b9daf
-- 
2.37.3