On Sun, 08 Jul 2012 02:04:32 -0700, Jonathan Nieder <jrnie...@gmail.com> wrote:

So presumably it's the new writes to the ACPI_BITREG_ARB_DISABLE
register that cause trouble.  The patch below tests that guess.

Given the complexity of the ACPI_DEBUG logging (particularly the
console part), I decided to give your patch a shot directly.

Result: the system no longer locks up. I paste the following info
so you can make sure I'm working with the correct commit:

[Sun Jul 08 02:41:37 -0700 -- alvarezp@octavio:~/src/linux]
$ git status
# Not currently on any branch.
# Changes not staged for commit:
#   (use "git add <file>..." to update what will be committed)
# (use "git checkout -- <file>..." to discard changes in working directory)
#
#       modified:   drivers/acpi/acpica/hwsleep.c
#
# Untracked files:
#   (use "git add <file>..." to include in what will be committed)
#
#       arch/x86/tools/relocs
no changes added to commit (use "git add" and/or "git commit -a")

[Sun Jul 08 02:41:41 -0700 -- alvarezp@octavio:~/src/linux]
$ git log HEAD^..HEAD
commit 2feec47d4c5f80b05f1650f5a24865718978eea4
Author: Bob Moore <robert.mo...@intel.com>
Date:   Tue Feb 14 15:00:53 2012 +0800

ACPICA: ACPI 5: Support for new FADT SleepStatus, SleepControl registers

    Adds sleep and wake support for systems with these registers.
    One new file, hwxfsleep.c

    Signed-off-by: Bob Moore <robert.mo...@intel.com>
    Signed-off-by: Len Brown <len.br...@intel.com>

[Sun Jul 08 02:41:49 -0700 -- alvarezp@octavio:~/src/linux]
$ git diff
diff --git a/drivers/acpi/acpica/hwsleep.c b/drivers/acpi/acpica/hwsleep.c
index 59a2a6b..66dd2b8 100644
--- a/drivers/acpi/acpica/hwsleep.c
+++ b/drivers/acpi/acpica/hwsleep.c
@@ -241,18 +241,6 @@ acpi_status acpi_hw_legacy_sleep(u8 sleep_state)
                return_ACPI_STATUS(status);
        }

-       if (sleep_state != ACPI_STATE_S5) {
-               /*
- * Disable BM arbitration. This feature is contained within an
-                * optional register (PM2 Control), so ignore a BAD_ADDRESS
-                * exception.
-                */
- status = acpi_write_bit_register(ACPI_BITREG_ARB_DISABLE, 1);
-               if (ACPI_FAILURE(status) && (status != AE_BAD_ADDRESS)) {
-                       return_ACPI_STATUS(status);
-               }
-       }
-
        /*
         * 1) Disable/Clear all GPEs
         * 2) Enable all wakeup GPEs
@@ -498,16 +486,6 @@ acpi_status acpi_hw_legacy_wake(u8 sleep_state)
                                    [ACPI_EVENT_POWER_BUTTON].
                                    status_register_id, ACPI_CLEAR_STATUS);

-       /*
-        * Enable BM arbitration. This feature is contained within an
-        * optional register (PM2 Control), so ignore a BAD_ADDRESS
-        * exception.
-        */
-       status = acpi_write_bit_register(ACPI_BITREG_ARB_DISABLE, 0);
-       if (ACPI_FAILURE(status) && (status != AE_BAD_ADDRESS)) {
-               return_ACPI_STATUS(status);
-       }
-
        acpi_hw_execute_SST(ACPI_SST_WORKING);
        return_ACPI_STATUS(status);
 }


Now for a complaint.  This would have been a lot easier if cleanups
that do not change behavior were split into separate commits --- one
commit per change.  That makes it easy to verify that each patch
correctly does what it promises with no unintended side effects.

I have to back you up on this one. This patch could have been 3 easily.
Git bisect would have done a better job.

The question is: if he had dont it that way, would the kernel have
compiled in intermediate commits?

diff --git i/drivers/acpi/acpica/hwsleep.c w/drivers/acpi/acpica/hwsleep.c
index 0ed85cac3231..615996a36bed 100644
--- i/drivers/acpi/acpica/hwsleep.c
+++ w/drivers/acpi/acpica/hwsleep.c
@@ -95,18 +95,6 @@ acpi_status acpi_hw_legacy_sleep(u8 sleep_state, u8 flags)
                return_ACPI_STATUS(status);
        }
-       if (sleep_state != ACPI_STATE_S5) {
-               /*
-                * Disable BM arbitration. This feature is contained within an
-                * optional register (PM2 Control), so ignore a BAD_ADDRESS
-                * exception.
-                */
-               status = acpi_write_bit_register(ACPI_BITREG_ARB_DISABLE, 1);
-               if (ACPI_FAILURE(status) && (status != AE_BAD_ADDRESS)) {
-                       return_ACPI_STATUS(status);
-               }
-       }
-
        /*
         * 1) Disable/Clear all GPEs
         * 2) Enable all wakeup GPEs
@@ -364,16 +352,6 @@ acpi_status acpi_hw_legacy_wake(u8 sleep_state, u8 flags)
                                    [ACPI_EVENT_POWER_BUTTON].
                                    status_register_id, ACPI_CLEAR_STATUS);
-       /*
-        * Enable BM arbitration. This feature is contained within an
-        * optional register (PM2 Control), so ignore a BAD_ADDRESS
-        * exception.
-        */
-       status = acpi_write_bit_register(ACPI_BITREG_ARB_DISABLE, 0);
-       if (ACPI_FAILURE(status) && (status != AE_BAD_ADDRESS)) {
-               return_ACPI_STATUS(status);
-       }
-
        acpi_hw_execute_sleep_method(METHOD_PATHNAME__SST, ACPI_SST_WORKING);
        return_ACPI_STATUS(status);
 }

Thanks for the patch.

--
Octavio.



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