linux-kernel - [PATCH v2] mfd: kempld: Switch back to earlier ->init() behavior

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Message-ID: <7d2c7e92253d851194a781720051536cca2722b8.camel@secunet.com>
Date: Thu, 31 Jul 2025 14:45:00 +0000
From: "Heijligen, Thomas" <thomas.heijligen@...unet.com>
To: "lee@...nel.org" <lee@...nel.org>, "andriy.shevchenko@...ux.intel.com"
	<andriy.shevchenko@...ux.intel.com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
CC: "Huber, Nico" <Nico.Huber@...unet.com>, "michael.brunner@...tron.com"
	<michael.brunner@...tron.com>, "Schumann, Peter" <Peter.Schumann@...unet.com>
Subject: [PATCH v2] mfd: kempld: Switch back to earlier ->init() behavior

Commit 9e36775c22c7 ("mfd: kempld: Remove custom DMI matching code")
removes the ability to load the driver if no matching system DMI data
is found. Before this commit the driver could be loaded using
alternative methods such as ACPI or `force_device_id` in the absence
of a matching system DMI entry.

Restore this ability while keeping the refactored
`platform_device_info` table.

Signed-off-by: Thomas Heijligen <thomas.heijligen@...unet.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
---
 drivers/mfd/kempld-core.c | 32 ++++++++++++++++++--------------
 1 file changed, 18 insertions(+), 14 deletions(-)

diff --git a/drivers/mfd/kempld-core.c b/drivers/mfd/kempld-core.c
index c5bfb6440a93..77980c7fc31f 100644
--- a/drivers/mfd/kempld-core.c
+++ b/drivers/mfd/kempld-core.c
@@ -779,22 +779,26 @@ MODULE_DEVICE_TABLE(dmi, kempld_dmi_table);
 static int __init kempld_init(void)
 {
 	const struct dmi_system_id *id;
-	int ret = -ENODEV;
 
-	for (id = dmi_first_match(kempld_dmi_table); id; id = dmi_first_match(id + 1)) {
-		/* Check, if user asked for the exact device ID match */
-		if (force_device_id[0] && !strstr(id->ident, force_device_id))
-			continue;
-
-		ret = kempld_create_platform_device(&kempld_platform_data_generic);
-		if (ret)
-			continue;
-
-		break;
+	/*
+	 * This custom DMI iteration allows the driver to be initialized in three ways:
+	 * - When a forced_device_id string matches any ident in the kempld_dmi_table,
+	 *   regardless of whether the DMI device is present in the system dmi table.
+	 * - When a matching entry is present in the DMI system tabe.
+	 * - Through alternative mechanisms like ACPI.
+	 */
+	if (force_device_id[0]) {
+		for (id = kempld_dmi_table; id->matches[0].slot != DMI_NONE; id++)
+			if (strstr(id->ident, force_device_id))
+				if (!kempld_create_platform_device(&kempld_platform_data_generic))
+					break;
+		if (id->matches[0].slot == DMI_NONE)
+			return -ENODEV;
+	} else {
+		for (id = dmi_first_match(kempld_dmi_table); id; id = dmi_first_match(id+1))
+			if (kempld_create_platform_device(&kempld_platform_data_generic))
+				break;
 	}
-	if (ret)
-		return ret;
-
 	return platform_driver_register(&kempld_driver);
 }
 
-- 
2.50.0