Re: [UBUNTU:acpi/ec] Use semaphore instead of spinlock
From: Andrew Morton
Date: Mon Jun 19 2006 - 21:05:39 EST
Randy Dunlap <randy.dunlap@xxxxxxxxxx> wrote:
>
> Andrew Morton wrote:
> > Bongani Hlope <bhlope@xxxxxxxxxx> wrote:
> >>> @@ -342,7 +341,10 @@ static int acpi_ec_poll_read(union acpi_
> >>> return_VALUE(-ENODEV);
> >>> }
> >>>
> >>> - spin_lock_irqsave(&ec->poll.lock, flags);
> >>> + if (down_interruptible(&ec->polling.sem)) {
> >> ^^^^
> >> isn't this suppose to be: &ec->poll.sem
> >
> > Good question. Did it get resolved?
>
> I posted a corrected patch that does that.
> No responses from the ACPI people.
>
OK. It appears that this patch is already somewhat partially in the acpi
devel tree.
But it's using a semaphore and not a mutex, and those udelays are still in
there.
Here's what git-apci has for that file:
diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index eee0864..18b3ea9 100644
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -116,7 +116,7 @@ union acpi_ec {
struct acpi_generic_address command_addr;
struct acpi_generic_address data_addr;
unsigned long global_lock;
- spinlock_t lock;
+ struct semaphore sem;
} poll;
};
@@ -323,7 +323,6 @@ static int acpi_ec_poll_read(union acpi_
{
acpi_status status = AE_OK;
int result = 0;
- unsigned long flags = 0;
u32 glk = 0;
ACPI_FUNCTION_TRACE("acpi_ec_read");
@@ -339,8 +338,11 @@ static int acpi_ec_poll_read(union acpi_
return_VALUE(-ENODEV);
}
- spin_lock_irqsave(&ec->poll.lock, flags);
-
+ if (down_interruptible(&ec->poll.sem)) {
+ result = -ERESTARTSYS;
+ goto end_nosem;
+ }
+
acpi_hw_low_level_write(8, ACPI_EC_COMMAND_READ,
&ec->common.command_addr);
result = acpi_ec_wait(ec, ACPI_EC_EVENT_IBE);
@@ -358,8 +360,8 @@ static int acpi_ec_poll_read(union acpi_
*data, address));
end:
- spin_unlock_irqrestore(&ec->poll.lock, flags);
-
+ up(&ec->poll.sem);
+end_nosem:
if (ec->common.global_lock)
acpi_release_global_lock(glk);
@@ -370,7 +372,6 @@ static int acpi_ec_poll_write(union acpi
{
int result = 0;
acpi_status status = AE_OK;
- unsigned long flags = 0;
u32 glk = 0;
ACPI_FUNCTION_TRACE("acpi_ec_write");
@@ -384,8 +385,11 @@ static int acpi_ec_poll_write(union acpi
return_VALUE(-ENODEV);
}
- spin_lock_irqsave(&ec->poll.lock, flags);
-
+ if (down_interruptible(&ec->poll.sem)) {
+ result = -ERESTARTSYS;
+ goto end_nosem;
+ }
+
acpi_hw_low_level_write(8, ACPI_EC_COMMAND_WRITE,
&ec->common.command_addr);
result = acpi_ec_wait(ec, ACPI_EC_EVENT_IBE);
@@ -406,8 +410,8 @@ static int acpi_ec_poll_write(union acpi
data, address));
end:
- spin_unlock_irqrestore(&ec->poll.lock, flags);
-
+ up(&ec->poll.sem);
+end_nosem:
if (ec->common.global_lock)
acpi_release_global_lock(glk);
@@ -568,7 +572,6 @@ static int acpi_ec_poll_query(union acpi
{
int result = 0;
acpi_status status = AE_OK;
- unsigned long flags = 0;
u32 glk = 0;
ACPI_FUNCTION_TRACE("acpi_ec_query");
@@ -589,8 +592,11 @@ static int acpi_ec_poll_query(union acpi
* Note that successful completion of the query causes the ACPI_EC_SCI
* bit to be cleared (and thus clearing the interrupt source).
*/
- spin_lock_irqsave(&ec->poll.lock, flags);
-
+ if (down_interruptible(&ec->poll.sem)) {
+ result = -ERESTARTSYS;
+ goto end_nosem;
+ }
+
acpi_hw_low_level_write(8, ACPI_EC_COMMAND_QUERY,
&ec->common.command_addr);
result = acpi_ec_wait(ec, ACPI_EC_EVENT_OBF);
@@ -602,8 +608,8 @@ static int acpi_ec_poll_query(union acpi
result = -ENODATA;
end:
- spin_unlock_irqrestore(&ec->poll.lock, flags);
-
+ up(&ec->poll.sem);
+end_nosem:
if (ec->common.global_lock)
acpi_release_global_lock(glk);
@@ -680,7 +686,6 @@ static void acpi_ec_gpe_poll_query(void
{
union acpi_ec *ec = (union acpi_ec *)ec_cxt;
u32 value = 0;
- unsigned long flags = 0;
static char object_name[5] = { '_', 'Q', '0', '0', '\0' };
const char hex[] = { '0', '1', '2', '3', '4', '5', '6', '7',
'8', '9', 'A', 'B', 'C', 'D', 'E', 'F'
@@ -691,9 +696,11 @@ static void acpi_ec_gpe_poll_query(void
if (!ec_cxt)
goto end;
- spin_lock_irqsave(&ec->poll.lock, flags);
+ if (down_interruptible (&ec->poll.sem)) {
+ return_VOID;
+ }
acpi_hw_low_level_read(8, &value, &ec->common.command_addr);
- spin_unlock_irqrestore(&ec->poll.lock, flags);
+ up(&ec->poll.sem);
/* TBD: Implement asynch events!
* NOTE: All we care about are EC-SCI's. Other EC events are
@@ -763,8 +770,7 @@ static u32 acpi_ec_gpe_poll_handler(void
acpi_disable_gpe(NULL, ec->common.gpe_bit, ACPI_ISR);
- status = acpi_os_queue_for_execution(OSD_PRIORITY_GPE,
- acpi_ec_gpe_query, ec);
+ status = acpi_os_execute(OSL_EC_POLL_HANDLER, acpi_ec_gpe_query, ec);
if (status == AE_OK)
return ACPI_INTERRUPT_HANDLED;
@@ -799,7 +805,7 @@ static u32 acpi_ec_gpe_intr_handler(void
if (value & ACPI_EC_FLAG_SCI) {
atomic_add(1, &ec->intr.pending_gpe);
- status = acpi_os_queue_for_execution(OSD_PRIORITY_GPE,
+ status = acpi_os_execute(OSL_EC_BURST_HANDLER,
acpi_ec_gpe_query, ec);
return status == AE_OK ?
ACPI_INTERRUPT_HANDLED : ACPI_INTERRUPT_NOT_HANDLED;
@@ -991,7 +997,6 @@ static int acpi_ec_poll_add(struct acpi_
int result = 0;
acpi_status status = AE_OK;
union acpi_ec *ec = NULL;
- unsigned long uid;
ACPI_FUNCTION_TRACE("acpi_ec_add");
@@ -1005,7 +1010,7 @@ static int acpi_ec_poll_add(struct acpi_
ec->common.handle = device->handle;
ec->common.uid = -1;
- spin_lock_init(&ec->poll.lock);
+ init_MUTEX(&ec->poll.sem);
strcpy(acpi_device_name(device), ACPI_EC_DEVICE_NAME);
strcpy(acpi_device_class(device), ACPI_EC_CLASS);
acpi_driver_data(device) = ec;
@@ -1014,10 +1019,9 @@ static int acpi_ec_poll_add(struct acpi_
acpi_evaluate_integer(ec->common.handle, "_GLK", NULL,
&ec->common.global_lock);
- /* If our UID matches the UID for the ECDT-enumerated EC,
- we now have the *real* EC info, so kill the makeshift one. */
- acpi_evaluate_integer(ec->common.handle, "_UID", NULL, &uid);
- if (ec_ecdt && ec_ecdt->common.uid == uid) {
+ /* XXX we don't test uids, because on some boxes ecdt uid = 0, see:
+ http://bugzilla.kernel.org/show_bug.cgi?id=6111 */
+ if (ec_ecdt) {
acpi_remove_address_space_handler(ACPI_ROOT_OBJECT,
ACPI_ADR_SPACE_EC,
&acpi_ec_space_handler);
@@ -1062,7 +1066,6 @@ static int acpi_ec_intr_add(struct acpi_
int result = 0;
acpi_status status = AE_OK;
union acpi_ec *ec = NULL;
- unsigned long uid;
ACPI_FUNCTION_TRACE("acpi_ec_add");
@@ -1088,10 +1091,9 @@ static int acpi_ec_intr_add(struct acpi_
acpi_evaluate_integer(ec->common.handle, "_GLK", NULL,
&ec->common.global_lock);
- /* If our UID matches the UID for the ECDT-enumerated EC,
- we now have the *real* EC info, so kill the makeshift one. */
- acpi_evaluate_integer(ec->common.handle, "_UID", NULL, &uid);
- if (ec_ecdt && ec_ecdt->common.uid == uid) {
+ /* XXX we don't test uids, because on some boxes ecdt uid = 0, see:
+ http://bugzilla.kernel.org/show_bug.cgi?id=6111 */
+ if (ec_ecdt) {
acpi_remove_address_space_handler(ACPI_ROOT_OBJECT,
ACPI_ADR_SPACE_EC,
&acpi_ec_space_handler);
@@ -1300,7 +1302,7 @@ acpi_fake_ecdt_poll_callback(acpi_handle
&ec_ecdt->common.gpe_bit);
if (ACPI_FAILURE(status))
return status;
- spin_lock_init(&ec_ecdt->poll.lock);
+ init_MUTEX(&ec_ecdt->poll.sem);
ec_ecdt->common.global_lock = TRUE;
ec_ecdt->common.handle = handle;
@@ -1416,7 +1418,7 @@ static int __init acpi_ec_poll_get_real_
ec_ecdt->common.status_addr = ecdt_ptr->ec_control;
ec_ecdt->common.data_addr = ecdt_ptr->ec_data;
ec_ecdt->common.gpe_bit = ecdt_ptr->gpe_bit;
- spin_lock_init(&ec_ecdt->poll.lock);
+ init_MUTEX(&ec_ecdt->poll.sem);
/* use the GL just to be safe */
ec_ecdt->common.global_lock = TRUE;
ec_ecdt->common.uid = ecdt_ptr->uid;
-
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