[U-Boot,16/22] x86: apci: Change PM1_CNT register access to RMW

Submitted by Bin Meng on March 16, 2017, 2:26 p.m.

Details

Message ID 1489674408-17498-17-git-send-email-bmeng.cn@gmail.com
State New
Delegated to: Bin Meng
Headers show

Commit Message

Bin Meng March 16, 2017, 2:26 p.m.
In enter_acpi_mode() PM1_CNT register is changed to PM1_CNT_SCI_EN
directly without preserving its previous value. Update to change
the register access to read-modify-write (RMW).

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
---

 arch/x86/lib/acpi_table.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Comments

Simon Glass March 21, 2017, 8:07 p.m.
On 16 March 2017 at 08:26, Bin Meng <bmeng.cn@gmail.com> wrote:
> In enter_acpi_mode() PM1_CNT register is changed to PM1_CNT_SCI_EN
> directly without preserving its previous value. Update to change
> the register access to read-modify-write (RMW).
>
> Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
> ---
>
>  arch/x86/lib/acpi_table.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)

Reviewed-by: Simon Glass <sjg@chromium.org>

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diff --git a/arch/x86/lib/acpi_table.c b/arch/x86/lib/acpi_table.c
index f118345..8be8120 100644
--- a/arch/x86/lib/acpi_table.c
+++ b/arch/x86/lib/acpi_table.c
@@ -306,6 +306,8 @@  static void acpi_create_mcfg(struct acpi_mcfg *mcfg)
 
 static void enter_acpi_mode(int pm1_cnt)
 {
+	u16 val = inw(pm1_cnt);
+
 	/*
 	 * PM1_CNT register bit0 selects the power management event to be
 	 * either an SCI or SMI interrupt. When this bit is set, then power
@@ -320,7 +322,7 @@  static void enter_acpi_mode(int pm1_cnt)
 	 * system, and expose ourselves to OSPM as working under ACPI mode
 	 * already, turn this bit on.
 	 */
-	outw(PM1_CNT_SCI_EN, pm1_cnt);
+	outw(val | PM1_CNT_SCI_EN, pm1_cnt);
 }
 
 /*