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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Hans de Goede <hdegoede@redhat.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.9 078/159] platform/x86: msi-laptop: Fix old-ec check for backlight registering
Date:   Mon, 24 Oct 2022 13:30:32 +0200
Message-Id: <20221024112952.291810297@linuxfoundation.org>
In-Reply-To: <20221024112949.358278806@linuxfoundation.org>
References: <20221024112949.358278806@linuxfoundation.org>
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From: Hans de Goede <hdegoede@redhat.com>

[ Upstream commit 83ac7a1c2ed5f17caa07cbbc84bad3c05dc3bf22 ]

Commit 2cc6c717799f ("msi-laptop: Port to new backlight interface
selection API") replaced this check:

	if (!quirks->old_ec_model || acpi_video_backlight_support())
		pr_info("Brightness ignored, ...");
	else
		do_register();

With:

	if (quirks->old_ec_model ||
	    acpi_video_get_backlight_type() == acpi_backlight_vendor)
		do_register();

But since the do_register() part was part of the else branch, the entire
condition should be inverted.  So not only the 2 statements on either
side of the || should be inverted, but the || itself should be replaced
with a &&.

In practice this has likely not been an issue because the new-ec models
(old_ec_model==false) likely all support ACPI video backlight control,
making acpi_video_get_backlight_type() return acpi_backlight_video
turning the second part of the || also false when old_ec_model == false.

Fixes: 2cc6c717799f ("msi-laptop: Port to new backlight interface selection API")
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20220825141336.208597-1-hdegoede@redhat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/platform/x86/msi-laptop.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/platform/x86/msi-laptop.c b/drivers/platform/x86/msi-laptop.c
index 42317704629d..c2a1bc8e9fef 100644
--- a/drivers/platform/x86/msi-laptop.c
+++ b/drivers/platform/x86/msi-laptop.c
@@ -1069,8 +1069,7 @@ static int __init msi_init(void)
 		return -EINVAL;
 
 	/* Register backlight stuff */
-
-	if (quirks->old_ec_model ||
+	if (quirks->old_ec_model &&
 	    acpi_video_get_backlight_type() == acpi_backlight_vendor) {
 		struct backlight_properties props;
 		memset(&props, 0, sizeof(struct backlight_properties));
-- 
2.35.1