linux-kernel - [PATCH 5.16 0958/1017] platform/chrome: cros_ec

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Date:   Tue,  5 Apr 2022 09:31:11 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Alyssa Ross <hi@...ssa.is>,
        Tzung-Bi Shih <tzungbi@...gle.com>,
        Prashant Malani <pmalani@...omium.org>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Benson Leung <bleung@...omium.org>
Subject: [PATCH 5.16 0958/1017] platform/chrome: cros_ec_typec: Check for EC device

From: Prashant Malani <pmalani@...omium.org>

commit ffebd90532728086007038986900426544e3df4e upstream.

The Type C ACPI device on older Chromebooks is not generated correctly
(since their EC firmware doesn't support the new commands required). In
such cases, the crafted ACPI device doesn't have an EC parent, and it is
therefore not useful (it shouldn't be generated in the first place since
the EC firmware doesn't support any of the Type C commands).

To handle devices which use these older firmware revisions, check for
the parent EC device handle, and fail the probe if it's not found.

Fixes: fdc6b21e2444 ("platform/chrome: Add Type C connector class driver")
Reported-by: Alyssa Ross <hi@...ssa.is>
Reviewed-by: Tzung-Bi Shih <tzungbi@...gle.com>
Signed-off-by: Prashant Malani <pmalani@...omium.org>
Acked-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Reviewed-by: Alyssa Ross <hi@...ssa.is>
Tested-by: Alyssa Ross <hi@...ssa.is>
Link: https://lore.kernel.org/r/20220126190219.3095419-1-pmalani@chromium.org
Signed-off-by: Benson Leung <bleung@...omium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/platform/chrome/cros_ec_typec.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/drivers/platform/chrome/cros_ec_typec.c
+++ b/drivers/platform/chrome/cros_ec_typec.c
@@ -1075,7 +1075,13 @@ static int cros_typec_probe(struct platf
 		return -ENOMEM;
 
 	typec->dev = dev;
+
 	typec->ec = dev_get_drvdata(pdev->dev.parent);
+	if (!typec->ec) {
+		dev_err(dev, "couldn't find parent EC device\n");
+		return -ENODEV;
+	}
+
 	platform_set_drvdata(pdev, typec);
 
 	ret = cros_typec_get_cmd_version(typec);