[PATCH 019/112] ACPI: EC: Do the byte access with a fast path

Len Brown
2008-02-07T09:35:42Z

From: Alexey Starikovskiy <astarikovskiy@suse.de>

Specification allows only byte access for EC region, so
make it separate from bug-compatible multi-byte access.
Also do not allow return of garbage in supplied *value.

Reference: http://bugzilla.kernel.org/show_bug.cgi?id=9341

Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>
---
drivers/acpi/ec.c | 15 +++++++++++----
1 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index d411017..63862df 100644
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -563,7 +563,7 @@ acpi_ec_space_handler(u32 function, acpi_physical_address address,
void *handler_context, void *region_context)
{
struct acpi_ec *ec = handler_context;
- int result = 0, i = 0;
+ int result = 0, i;
u8 temp = 0;

if ((address > 0xFF) || !value || !handler_context)
@@ -575,7 +575,16 @@ acpi_ec_space_handler(u32 function, acpi_physical_address address,
if (bits != 8 && acpi_strict)
return AE_BAD_PARAMETER;

- while (bits - i > 0) {
+ if (function == ACPI_READ) {
+ result = acpi_ec_read(ec, address, &temp);
+ *value = temp;
+ } else {
+ temp = 0xff & (*value);
+ result = acpi_ec_write(ec, address, temp);
+ }
+
+ for (i = 8; unlikely(bits - i > 0); i += 8) {
+ ++address;
if (function == ACPI_READ) {
result = acpi_ec_read(ec, address, &temp);
(*value) |= ((acpi_integer)temp) << i;
@@ -583,8 +592,6 @@ acpi_ec_space_handler(u32 function, acpi_physical_address address,
temp = 0xff & ((*value) >> i);
result = acpi_ec_write(ec, address, temp);
}
- i += 8;
- ++address;
}

switch (result) {
--
1.5.4.23.gef5b9