[PATCH] drm/nouveau/acpi: de-dup use of DSM methods

[Peter Wu <lekensteyn@gmail.com>]

Observe that nouveau_optimus_dsm and nouveau_dsm are equal except for
the parameters handling (UUID, revision ID and function arguments). The
function arguments are passed as Buffer in the "optimus dsm" and Integer
in "nvidia dsm". As buffers are implicitly converted to integers, merge
both functions.

The ACPI spec defines the fourth parameter (Arg3 a.k.a. "function
arguments") as Package, but many BIOSes expect a Buffer instead. For
instance, for the "nvidia DSM", the Lenovo T410s uses CreateByteField on
Arg3 which does not work with a package. The Clevo B7130 does something
similar for the "Optimus DSM". Unfortunately, this means that the
following ACPI warning (introduced with 29a241c) cannot be fixed (when
toggling power or muxing):

    ACPI Warning: \_SB_.PCI0.GFX0._DSM: Argument #4 type mismatch - Found [Buffer], ACPI requires [Package] (20130517/nsarguments-95)
    ACPI Warning: \_SB_.PCI0.GFX0._DSM: Argument #4 type mismatch - Found [Buffer], ACPI requires [Package] (20130517/nsarguments-95)
    ACPI Warning: \_SB_.PCI0.P0P2.PEGP._DSM: Argument #4 type mismatch - Found [Buffer], ACPI requires [Package] (20130517/nsarguments-95)
    ACPI Warning: \_SB_.PCI0.P0P2.PEGP._DSM: Argument #4 type mismatch - Found [Buffer], ACPI requires [Package] (20130517/nsarguments-95)

Signed-off-by: Peter Wu <lekensteyn@gmail.com>
---
 drivers/gpu/drm/nouveau/nouveau_acpi.c | 67 ++++++++++------------------------
 1 file changed, 20 insertions(+), 47 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_acpi.c b/drivers/gpu/drm/nouveau/nouveau_acpi.c
index d97f200..a75684f 100644
--- a/drivers/gpu/drm/nouveau/nouveau_acpi.c
+++ b/drivers/gpu/drm/nouveau/nouveau_acpi.c
@@ -46,6 +46,9 @@ bool nouveau_is_v1_dsm(void) {
 #define NOUVEAU_DSM_HAS_MUX 0x1
 #define NOUVEAU_DSM_HAS_OPT 0x2
 
+#define NOUVEAU_DSM_REVID_NVIDIA 0x102
+#define NOUVEAU_DSM_REVID_OPTIMUS 0x100
+
 static const char nouveau_dsm_muid[] = {
 	0xA0, 0xA0, 0x95, 0x9D, 0x60, 0x00, 0x48, 0x4D,
 	0xB3, 0x4D, 0x7E, 0x5F, 0xEA, 0x12, 0x9F, 0xD4,
@@ -56,7 +59,8 @@ static const char nouveau_op_dsm_muid[] = {
 	0xA7, 0x2B, 0x60, 0x42, 0xA6, 0xB5, 0xBE, 0xE0,
 };
 
-static int nouveau_optimus_dsm(acpi_handle handle, int func, int arg, uint32_t *result)
+static int nouveau_call_dsm(acpi_handle handle, const char *uuid, int revid,
+	int func, int arg, uint32_t *result)
 {
 	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
 	struct acpi_object_list input;
@@ -68,12 +72,15 @@ static int nouveau_optimus_dsm(acpi_handle handle, int func, int arg, uint32_t *
 	input.count = 4;
 	input.pointer = params;
 	params[0].type = ACPI_TYPE_BUFFER;
-	params[0].buffer.length = sizeof(nouveau_op_dsm_muid);
-	params[0].buffer.pointer = (char *)nouveau_op_dsm_muid;
+	params[0].buffer.length = 16;
+	params[0].buffer.pointer = (char *)uuid;
 	params[1].type = ACPI_TYPE_INTEGER;
-	params[1].integer.value = 0x00000100;
+	params[1].integer.value = revid;
 	params[2].type = ACPI_TYPE_INTEGER;
 	params[2].integer.value = func;
+	/* Although the ACPI spec defines Arg3 as a Package, in practise
+	 * implementations expect a Buffer (CreateWordField and Index functions
+	 * are applied to it). */
 	params[3].type = ACPI_TYPE_BUFFER;
 	params[3].buffer.length = 4;
 	/* ACPI is little endian, AABBCCDD becomes {DD,CC,BB,AA} */
@@ -108,50 +115,16 @@ static int nouveau_optimus_dsm(acpi_handle handle, int func, int arg, uint32_t *
 	return 0;
 }
 
-static int nouveau_dsm(acpi_handle handle, int func, int arg, uint32_t *result)
-{
-	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
-	struct acpi_object_list input;
-	union acpi_object params[4];
-	union acpi_object *obj;
-	int err;
-
-	input.count = 4;
-	input.pointer = params;
-	params[0].type = ACPI_TYPE_BUFFER;
-	params[0].buffer.length = sizeof(nouveau_dsm_muid);
-	params[0].buffer.pointer = (char *)nouveau_dsm_muid;
-	params[1].type = ACPI_TYPE_INTEGER;
-	params[1].integer.value = 0x00000102;
-	params[2].type = ACPI_TYPE_INTEGER;
-	params[2].integer.value = func;
-	params[3].type = ACPI_TYPE_INTEGER;
-	params[3].integer.value = arg;
-
-	err = acpi_evaluate_object(handle, "_DSM", &input, &output);
-	if (err) {
-		printk(KERN_INFO "failed to evaluate _DSM: %d\n", err);
-		return err;
-	}
-
-	obj = (union acpi_object *)output.pointer;
-
-	if (obj->type == ACPI_TYPE_INTEGER)
-		if (obj->integer.value == 0x80000002)
-			return -ENODEV;
-
-	if (obj->type == ACPI_TYPE_BUFFER) {
-		if (obj->buffer.length == 4 && result) {
-			*result = 0;
-			*result |= obj->buffer.pointer[0];
-			*result |= (obj->buffer.pointer[1] << 8);
-			*result |= (obj->buffer.pointer[2] << 16);
-			*result |= (obj->buffer.pointer[3] << 24);
-		}
-	}
+static int nouveau_optimus_dsm(acpi_handle handle, int func,
+	int arg, uint32_t *result) {
+	return nouveau_call_dsm(handle, nouveau_op_dsm_muid,
+			NOUVEAU_DSM_REVID_OPTIMUS, func, arg, result);
+}
 
-	kfree(output.pointer);
-	return 0;
+static int nouveau_dsm(acpi_handle handle, int func,
+	int arg, uint32_t *result) {
+	return nouveau_call_dsm(handle, nouveau_dsm_muid,
+			NOUVEAU_DSM_REVID_NVIDIA, func, arg, result);
 }
 
 /* Returns 1 if a DSM function is usable and 0 otherwise */
-- 
1.8.3.4