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Subject: [PATCH v4 03/13] platform/x86: asus-wmi: Increase input buffer size
 of WMI methods
From:   Yurii Pavlovskyi <yurii.pavlovskyi@gmail.com>
Cc:     Corentin Chary <corentin.chary@gmail.com>,
        Darren Hart <dvhart@infradead.org>,
        Andy Shevchenko <andy@infradead.org>,
        Daniel Drake <drake@endlessm.com>,
        Chris Chiu <chiu@endlessm.com>,
        acpi4asus-user@lists.sourceforge.net,
        platform-driver-x86@vger.kernel.org, linux-kernel@vger.kernel.org
References: <c8cdb347-e206-76b2-0d43-546ef660ffb7@gmail.com>
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Date:   Tue, 14 May 2019 20:54:50 +0200
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The asus-nb-wmi driver is matched by WMI alias but fails to load on TUF
Gaming series laptops producing multiple ACPI errors in the kernel log.

The input buffer for WMI method invocation size is 2 dwords, whereas
3 are expected by this model.

FX505GM:
..
Method (WMNB, 3, Serialized)
{
    P8XH (Zero, 0x11)
    CreateDWordField (Arg2, Zero, IIA0)
    CreateDWordField (Arg2, 0x04, IIA1)
    CreateDWordField (Arg2, 0x08, IIA2)
    Local0 = (Arg1 & 0xFFFFFFFF)
    ...

Compare with older K54C:
...
Method (WMNB, 3, NotSerialized)
{
    CreateDWordField (Arg2, 0x00, IIA0)
    CreateDWordField (Arg2, 0x04, IIA1)
    Local0 = (Arg1 & 0xFFFFFFFF)
    ...

Increase buffer size to 3 dwords. No negative consequences of this change
are expected, as the input buffer size is not verified. The original
function is replaced by a wrapper for a new method passing value 0 for the
last parameter. The new function will be used to control RGB keyboard
backlight.

Signed-off-by: Yurii Pavlovskyi <yurii.pavlovskyi@gmail.com>
---
One of current kernel errors:
ACPI BIOS Error (bug): AE_AML_BUFFER_LIMIT, Field [IIA2] at bit offset/
	length 64/32 exceeds size of target Buffer (64 bits)
	(20190215/dsopcode-203)
[ 4528.573948] No Local Variables are initialized for Method [WMNB]
[ 4528.573949] Initialized Arguments for Method [WMNB]:  (3 arguments
	defined for method invocation)
[ 4528.573950]   Arg0:   00000000bd1bea5a <Obj>
	Integer 0000000000000000
[ 4528.573952]   Arg1:   00000000d414dc53 <Obj>
	Integer 000000004E464741
[ 4528.573954]   Arg2:   00000000fcefea4b <Obj>
	Buffer(8) F0 95 08 00 00 00 00 00
[ 4528.573959] ACPI Error: Aborting method \_SB.ATKD.WMNB due to previous
	error (AE_AML_BUFFER_LIMIT) (20190215/psparse-531)
[ 4528.686425] asus-nb-wmi: probe of asus-nb-wmi failed with error -5
---
 drivers/platform/x86/asus-wmi.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
index 84d7fc6f941c..6b35c1f00a3e 100644
--- a/drivers/platform/x86/asus-wmi.c
+++ b/drivers/platform/x86/asus-wmi.c
@@ -98,6 +98,7 @@ static bool ashs_present(void)
 struct bios_args {
 	u32 arg0;
 	u32 arg1;
+	u32 arg2; /* At least TUF Gaming series uses 3 dword input buffer. */
 } __packed;
 
 /*
@@ -224,11 +225,13 @@ static void asus_wmi_input_exit(struct asus_wmi *asus)
 	asus->inputdev = NULL;
 }
 
-int asus_wmi_evaluate_method(u32 method_id, u32 arg0, u32 arg1, u32 *retval)
+static int asus_wmi_evaluate_method3(u32 method_id,
+		u32 arg0, u32 arg1, u32 arg2, u32 *retval)
 {
 	struct bios_args args = {
 		.arg0 = arg0,
 		.arg1 = arg1,
+		.arg2 = arg2,
 	};
 	struct acpi_buffer input = { (acpi_size) sizeof(args), &args };
 	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
@@ -260,6 +263,11 @@ int asus_wmi_evaluate_method(u32 method_id, u32 arg0, u32 arg1, u32 *retval)
 
 	return 0;
 }
+
+int asus_wmi_evaluate_method(u32 method_id, u32 arg0, u32 arg1, u32 *retval)
+{
+	return asus_wmi_evaluate_method3(method_id, arg0, arg1, 0, retval);
+}
 EXPORT_SYMBOL_GPL(asus_wmi_evaluate_method);
 
 static int asus_wmi_evaluate_method_agfn(const struct acpi_buffer args)
-- 
2.17.1