linux-kernel - [PATCH 2/4] efi/bgrt: Drop BGRT status field reserved bits check

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Date:   Sat, 22 Jun 2019 10:51:04 +0200
From:   Ard Biesheuvel <ard.biesheuvel@...aro.org>
To:     linux-efi@...r.kernel.org, Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        linux-kernel@...r.kernel.org, Hans de Goede <hdegoede@...hat.com>,
        Jonathan Richardson <jonathan.richardson@...adcom.com>,
        Luo XinanX <xinanx.luo@...el.com>,
        "Prakhya, Sai Praneeth" <sai.praneeth.prakhya@...el.com>,
        Qian Cai <cai@....pw>, Tian Baofeng <baofeng.tian@...el.com>
Subject: [PATCH 2/4] efi/bgrt: Drop BGRT status field reserved bits check

From: Hans de Goede <hdegoede@...hat.com>

Starting with ACPI 6.2 bits 1 and 2 of the BGRT status field are no longer
reserved. These bits are now used to indicate if the image needs to be
rotated before being displayed.

The first device using these bits has now shown up (the GPD MicroPC) and
the reserved bits check causes us to reject the valid BGRT table on this
device.

Rather then changing the reserved bits check, allowing only the 2 new bits,
instead just completely remove it so that we do not end up with a similar
problem when more bits are added in the future.

Signed-off-by: Hans de Goede <hdegoede@...hat.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
---
 drivers/firmware/efi/efi-bgrt.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/drivers/firmware/efi/efi-bgrt.c b/drivers/firmware/efi/efi-bgrt.c
index a2384184a7de..b07c17643210 100644
--- a/drivers/firmware/efi/efi-bgrt.c
+++ b/drivers/firmware/efi/efi-bgrt.c
@@ -47,11 +47,6 @@ void __init efi_bgrt_init(struct acpi_table_header *table)
 		       bgrt->version);
 		goto out;
 	}
-	if (bgrt->status & 0xfe) {
-		pr_notice("Ignoring BGRT: reserved status bits are non-zero %u\n",
-		       bgrt->status);
-		goto out;
-	}
 	if (bgrt->image_type != 0) {
 		pr_notice("Ignoring BGRT: invalid image type %u (expected 0)\n",
 		       bgrt->image_type);
-- 
2.20.1