ACPI: handle systems which asynchoronously enable ACPI mode

Folklore suggested that such systems existed
in the pre-history of ACPI.

However, we removed the SCI_EN polling loop from
acpi_hw_set_mode() in b430acbd7c4b919886fa7fd92eeb7a695f1940d3
because it delayed resume by 3 seconds on boxes
that refused to set SCI_EN.

Matthew removed the call to acpi_enable() from
the suspend resume path.

James found a modern system that still needs to be polled
upon boot.

So here we restore the workaround, except that we
put it in acpi_enable() rather than the low level
acpi_hw_set_mode().

https://bugzilla.kernel.org/show_bug.cgi?id=16271

Signed-off-by: Len Brown <len.brown@intel.com>

diff --git a/drivers/acpi/acpica/evxfevnt.c b/drivers/acpi/acpica/evxfevnt.c
index d97b8dce16681ba90886a3b0e5546cf5b7060ce8..18b3f1468b7daeebd94dbe43216a4078951d9972 100644 (file)
--- a/drivers/acpi/acpica/evxfevnt.c
+++ b/drivers/acpi/acpica/evxfevnt.c
@@ -70,6 +70,7 @@ acpi_ev_get_gpe_device(struct acpi_gpe_xrupt_info *gpe_xrupt_info,
 acpi_status acpi_enable(void)
 {
        acpi_status status;
+       int retry;
 
        ACPI_FUNCTION_TRACE(acpi_enable);
 
@@ -98,16 +99,18 @@ acpi_status acpi_enable(void)
 
        /* Sanity check that transition succeeded */
 
-       if (acpi_hw_get_mode() != ACPI_SYS_MODE_ACPI) {
-               ACPI_ERROR((AE_INFO,
-                           "Hardware did not enter ACPI mode"));
-               return_ACPI_STATUS(AE_NO_HARDWARE_RESPONSE);
+       for (retry = 0; retry < 30000; ++retry) {
+               if (acpi_hw_get_mode() == ACPI_SYS_MODE_ACPI) {
+                       if (retry != 0)
+                               ACPI_WARNING((AE_INFO,
+                               "Platform took > %d00 usec to enter ACPI mode", retry));
+                       return_ACPI_STATUS(AE_OK);
+               }
+               acpi_os_stall(100);     /* 100 usec */
        }
 
-       ACPI_DEBUG_PRINT((ACPI_DB_INIT,
-                         "Transition to ACPI mode successful\n"));
-
-       return_ACPI_STATUS(AE_OK);
+       ACPI_ERROR((AE_INFO, "Hardware did not enter ACPI mode"));
+       return_ACPI_STATUS(AE_NO_HARDWARE_RESPONSE);
 }
 
 ACPI_EXPORT_SYMBOL(acpi_enable)