---

yaml
---
r: 141864
b: refs/heads/master
c: c3dd25f
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: f9ca058430333c9a24c5ca926aa445125f88df18
+refs/heads/master: c3dd25f4c1ca84baa170c0a3a15a884f4f06297e

trunk/drivers/acpi/acpica/aclocal.h

@@ -781,6 +781,10 @@ struct acpi_bit_register_info {
  */
 #define ACPI_PM1_STATUS_PRESERVED_BITS          0x0800	/* Bit 11 */
 
+/* Write-only bits must be zeroed by software */
+
+#define ACPI_PM1_CONTROL_WRITEONLY_BITS         0x2004	/* Bits 13, 2 */
+
 /* For control registers, both ignored and reserved bits must be preserved */
 
 #define ACPI_PM1_CONTROL_IGNORED_BITS           0x0201	/* Bits 9, 0(SCI_EN) */

trunk/drivers/acpi/acpica/hwregs.c

@@ -207,6 +207,13 @@ acpi_hw_register_read(u32 register_id, u32 * return_value)
 					       xpm1a_control_block,
 					       &acpi_gbl_FADT.
 					       xpm1b_control_block);
+
+		/*
+		 * Zero the write-only bits. From the ACPI specification, "Hardware
+		 * Write-Only Bits": "Upon reads to registers with write-only bits,
+		 * software masks out all write-only bits."
+		 */
+		value &= ~ACPI_PM1_CONTROL_WRITEONLY_BITS;
 		break;
 
 	case ACPI_REGISTER_PM2_CONTROL:	/* 8-bit access */