Subject: ACPI: Don't issue burst disable command if EC exits the burst mode
It is meaningless that OS continues to issue the burst disable command
if the EC already exits the burst mode. So if EC already exits the
burst mode, don't issue burst disable command again.
Signed-off-by: Zhao Yakui <yakui.zhao@xxxxxxxxx>
---
drivers/acpi/ec.c | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)
Index: linux-2.6/drivers/acpi/ec.c
===================================================================
--- linux-2.6.orig/drivers/acpi/ec.c
+++ linux-2.6/drivers/acpi/ec.c
@@ -327,12 +327,25 @@ static int acpi_ec_transaction(struct ac
int acpi_ec_burst_enable(struct acpi_ec *ec)
{
u8 d;
+ /*
+ * When burst enable command is issused, EC will put the EC burst
+ * acknowledge byte (0x90) into output buffer.
+ * Maybe it is worth checking the returned acknowledge bytes.
+ */
return acpi_ec_transaction(ec, ACPI_EC_BURST_ENABLE, NULL, 0, &d, 1, 0);
}
int acpi_ec_burst_disable(struct acpi_ec *ec)
{
- return acpi_ec_transaction(ec, ACPI_EC_BURST_DISABLE, NULL, 0, NULL, 0, 0);
+ u8 d = acpi_ec_read_status(ec);
+ if (d & ACPI_EC_FLAG_BURST) {
+ /*
+ * Only when EC is in burst mode, it is necessary to disable.
+ */
+ return acpi_ec_transaction(ec, ACPI_EC_BURST_DISABLE, NULL,
+ 0, NULL, 0, 0);
+ }
+ return 0;
}
static int acpi_ec_read(struct acpi_ec *ec, u8 address, u8 * data)
--
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