Re: patch for bugs 9998 and 10724

[Alexey Starikovskiy <astarikovskiy@suse.de>]

[-- Attachment #1: Type: text/plain, Size: 284 bytes --]

Here is the same patch as attachment for your convenience.
Alexey Starikovskiy wrote:
> Hi Andy,
> 
> I just uploaded patch for bugs 9998 and 10724, which solves the problem 
> of interrupt storm more cleanly.
> Could you please add this patch to testing?
> 
> Thanks,
> Alex.
> 
> 


[-- Attachment #2: fast_transaction.patch --]
[-- Type: text/x-diff, Size: 13609 bytes --]

ACPI: EC: do transaction from interrupt context

From: Alexey Starikovskiy <astarikovskiy@suse.de>

It is easier and faster to do transaction directly from interrupt context
rather than waking control thread.
Also, cleaner GPE storm avoidance is implemented.

Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
---

 drivers/acpi/ec.c |  250 ++++++++++++++++++++++++-----------------------------
 1 files changed, 113 insertions(+), 137 deletions(-)


diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index 13593f9..1f96f0e 100644
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -1,7 +1,7 @@
 /*
- *  ec.c - ACPI Embedded Controller Driver (v2.0)
+ *  ec.c - ACPI Embedded Controller Driver (v2.1)
  *
- *  Copyright (C) 2006, 2007 Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>
+ *  Copyright (C) 2006-2008 Alexey Starikovskiy <astarikovskiy@suse.de>
  *  Copyright (C) 2006 Denis Sadykov <denis.m.sadykov@intel.com>
  *  Copyright (C) 2004 Luming Yu <luming.yu@intel.com>
  *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
@@ -26,7 +26,7 @@
  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  */
 
-/* Uncomment next line to get verbose print outs*/
+/* Uncomment next line to get verbose printout */
 /* #define DEBUG */
 
 #include <linux/kernel.h>
@@ -65,22 +65,18 @@ enum ec_command {
 	ACPI_EC_COMMAND_QUERY = 0x84,
 };
 
-/* EC events */
-enum ec_event {
-	ACPI_EC_EVENT_OBF_1 = 1,	/* Output buffer full */
-	ACPI_EC_EVENT_IBF_0,		/* Input buffer empty */
-};
-
 #define ACPI_EC_DELAY		500	/* Wait 500ms max. during EC ops */
 #define ACPI_EC_UDELAY_GLK	1000	/* Wait 1ms max. to get global lock */
 #define ACPI_EC_UDELAY		100	/* Wait 100us before polling EC again */
 
+#define ACPI_EC_STORM_THRESHOLD 20	/* number of false interrupts
+					   per one transaction */
+
 enum {
-	EC_FLAGS_WAIT_GPE = 0,		/* Don't check status until GPE arrives */
 	EC_FLAGS_QUERY_PENDING,		/* Query is pending */
 	EC_FLAGS_GPE_MODE,		/* Expect GPE to be sent for status change */
 	EC_FLAGS_NO_GPE,		/* Don't use GPE mode */
-	EC_FLAGS_RESCHEDULE_POLL	/* Re-schedule poll */
+	EC_FLAGS_GPE_STORM		/* GPE storm detected */
 };
 
 /* If we find an EC via the ECDT, we need to keep a ptr to its context */
@@ -95,6 +91,14 @@ struct acpi_ec_query_handler {
 	u8 query_bit;
 };
 
+struct transaction_data {
+	const u8 *wdata;
+	u8 *rdata;
+	u8 command;
+	u8 wlen;
+	u8 rlen;
+};
+
 static struct acpi_ec {
 	acpi_handle handle;
 	unsigned long gpe;
@@ -105,7 +109,7 @@ static struct acpi_ec {
 	struct mutex lock;
 	wait_queue_head_t wait;
 	struct list_head list;
-	struct delayed_work work;
+	struct transaction_data t;
 	atomic_t irq_count;
 	u8 handlers_installed;
 } *boot_ec, *first_ec;
@@ -150,13 +154,13 @@ static inline u8 acpi_ec_read_data(struct acpi_ec *ec)
 {
 	u8 x = inb(ec->data_addr);
 	pr_debug(PREFIX "---> data = 0x%2.2x\n", x);
-	return inb(ec->data_addr);
+	return x;
 }
 
 static inline void acpi_ec_write_cmd(struct acpi_ec *ec, u8 command)
 {
 	pr_debug(PREFIX "<--- command = 0x%2.2x\n", command);
-	outb(command, ec->command_addr);
+	outb((ec->t.command = command), ec->command_addr);
 }
 
 static inline void acpi_ec_write_data(struct acpi_ec *ec, u8 data)
@@ -165,69 +169,60 @@ static inline void acpi_ec_write_data(struct acpi_ec *ec, u8 data)
 	outb(data, ec->data_addr);
 }
 
-static inline int acpi_ec_check_status(struct acpi_ec *ec, enum ec_event event)
-{
-	if (test_bit(EC_FLAGS_WAIT_GPE, &ec->flags))
-		return 0;
-	if (event == ACPI_EC_EVENT_OBF_1) {
-		if (acpi_ec_read_status(ec) & ACPI_EC_FLAG_OBF)
-			return 1;
-	} else if (event == ACPI_EC_EVENT_IBF_0) {
-		if (!(acpi_ec_read_status(ec) & ACPI_EC_FLAG_IBF))
-			return 1;
-	}
-
+static int ec_transaction_done(struct acpi_ec *ec) {
+	if (!ec->t.command)
+		return 1;
+	if (!ec->t.wlen && !ec->t.rlen)
+		return 1;
 	return 0;
 }
 
-static void ec_schedule_ec_poll(struct acpi_ec *ec)
+static void gpe_transaction(struct acpi_ec *ec, u8 status)
 {
-	if (test_bit(EC_FLAGS_RESCHEDULE_POLL, &ec->flags))
-		schedule_delayed_work(&ec->work,
-				      msecs_to_jiffies(ACPI_EC_DELAY));
+	if (!ec->t.command)
+		return;
+	if (ec->t.wlen > 0) {
+		if ((status & ACPI_EC_FLAG_IBF) == 0) {
+			acpi_ec_write_data(ec, *(ec->t.wdata++));
+			--ec->t.wlen;
+		} else
+			/* false interrupt, state didn't change */
+			atomic_inc(&ec->irq_count);
+
+	} else if (ec->t.rlen > 0) {
+		if ((status & ACPI_EC_FLAG_OBF) == 1) {
+			*(ec->t.rdata++) = acpi_ec_read_data(ec);
+			--ec->t.rlen;
+		} else
+			/* false interrupt, state didn't change */
+			atomic_inc(&ec->irq_count);
+	}
 }
 
-static void ec_switch_to_poll_mode(struct acpi_ec *ec)
+static int acpi_ec_wait(struct acpi_ec *ec)
 {
+	if (wait_event_timeout(ec->wait, ec_transaction_done(ec),
+			       msecs_to_jiffies(ACPI_EC_DELAY)))
+		return 0;
+	/* missing GPEs, switch back to poll mode */
+	if (printk_ratelimit())
+		pr_info(PREFIX "missing confirmations, "
+				"switch off interrupt mode.\n");
 	set_bit(EC_FLAGS_NO_GPE, &ec->flags);
 	clear_bit(EC_FLAGS_GPE_MODE, &ec->flags);
-	acpi_disable_gpe(NULL, ec->gpe, ACPI_NOT_ISR);
-	set_bit(EC_FLAGS_RESCHEDULE_POLL, &ec->flags);
+	return 1;
 }
 
-static int acpi_ec_wait(struct acpi_ec *ec, enum ec_event event, int force_poll)
+static void acpi_ec_gpe_query(void *ec_cxt);
+
+static int ec_check_sci(struct acpi_ec *ec, u8 state)
 {
-	atomic_set(&ec->irq_count, 0);
-	if (likely(test_bit(EC_FLAGS_GPE_MODE, &ec->flags)) &&
-	    likely(!force_poll)) {
-		if (wait_event_timeout(ec->wait, acpi_ec_check_status(ec, event),
-				       msecs_to_jiffies(ACPI_EC_DELAY)))
-			return 0;
-		clear_bit(EC_FLAGS_WAIT_GPE, &ec->flags);
-		if (acpi_ec_check_status(ec, event)) {
-			/* missing GPEs, switch back to poll mode */
-			if (printk_ratelimit())
-				pr_info(PREFIX "missing confirmations, "
-						"switch off interrupt mode.\n");
-			ec_switch_to_poll_mode(ec);
-			ec_schedule_ec_poll(ec);
-			return 0;
-		}
-	} else {
-		unsigned long delay = jiffies + msecs_to_jiffies(ACPI_EC_DELAY);
-		clear_bit(EC_FLAGS_WAIT_GPE, &ec->flags);
-		while (time_before(jiffies, delay)) {
-			if (acpi_ec_check_status(ec, event))
-				return 0;
-			msleep(1);
-		}
-		if (acpi_ec_check_status(ec,event))
-			return 0;
+	if (state & ACPI_EC_FLAG_SCI) {
+		if (!test_and_set_bit(EC_FLAGS_QUERY_PENDING, &ec->flags))
+			return acpi_os_execute(OSL_EC_BURST_HANDLER,
+				acpi_ec_gpe_query, ec);
 	}
-	pr_err(PREFIX "acpi_ec_wait timeout, status = 0x%2.2x, event = %s\n",
-		acpi_ec_read_status(ec),
-		(event == ACPI_EC_EVENT_OBF_1) ? "\"b0=1\"" : "\"b1=0\"");
-	return -ETIME;
+	return 0;
 }
 
 static int acpi_ec_transaction_unlocked(struct acpi_ec *ec, u8 command,
@@ -235,45 +230,53 @@ static int acpi_ec_transaction_unlocked(struct acpi_ec *ec, u8 command,
 					u8 * rdata, unsigned rdata_len,
 					int force_poll)
 {
-	int result = 0;
-	set_bit(EC_FLAGS_WAIT_GPE, &ec->flags);
+	unsigned long delay;
 	pr_debug(PREFIX "transaction start\n");
-	acpi_ec_write_cmd(ec, command);
-	for (; wdata_len > 0; --wdata_len) {
-		result = acpi_ec_wait(ec, ACPI_EC_EVENT_IBF_0, force_poll);
-		if (result) {
-			pr_err(PREFIX
-			       "write_cmd timeout, command = %d\n", command);
-			goto end;
-		}
-		set_bit(EC_FLAGS_WAIT_GPE, &ec->flags);
-		acpi_ec_write_data(ec, *(wdata++));
+	/* disable GPE during transaction if storm is detected */
+	if (test_bit(EC_FLAGS_GPE_STORM, &ec->flags)) {
+		set_bit(EC_FLAGS_NO_GPE, &ec->flags);
+		clear_bit(EC_FLAGS_GPE_MODE, &ec->flags);
+		acpi_disable_gpe(NULL, ec->gpe, ACPI_NOT_ISR);
 	}
-
-	if (!rdata_len) {
-		result = acpi_ec_wait(ec, ACPI_EC_EVENT_IBF_0, force_poll);
-		if (result) {
-			pr_err(PREFIX
-			       "finish-write timeout, command = %d\n", command);
-			goto end;
-		}
-	} else if (command == ACPI_EC_COMMAND_QUERY)
-		clear_bit(EC_FLAGS_QUERY_PENDING, &ec->flags);
-
-	for (; rdata_len > 0; --rdata_len) {
-		result = acpi_ec_wait(ec, ACPI_EC_EVENT_OBF_1, force_poll);
-		if (result) {
-			pr_err(PREFIX "read timeout, command = %d\n", command);
-			goto end;
+	atomic_set(&ec->irq_count, 0);
+	/* fill in transaction structure */
+	ec->t.wdata = wdata;
+	ec->t.wlen = wdata_len;
+	ec->t.rdata = rdata;
+	ec->t.rlen = rdata_len;
+	/* start transaction */
+	acpi_ec_write_cmd(ec, command);
+	/* if we selected poll mode or failed in GPE-mode do a poll loop */
+	if (force_poll ||
+	    !test_bit(EC_FLAGS_GPE_MODE, &ec->flags) ||
+	    acpi_ec_wait(ec)) {
+		delay = jiffies + msecs_to_jiffies(ACPI_EC_DELAY);
+		while (time_before(jiffies, delay)) {
+			gpe_transaction(ec, acpi_ec_read_status(ec));
+			msleep(1);
+			if (ec_transaction_done(ec))
+				goto end;
 		}
-		/* Don't expect GPE after last read */
-		if (rdata_len > 1)
-			set_bit(EC_FLAGS_WAIT_GPE, &ec->flags);
-		*(rdata++) = acpi_ec_read_data(ec);
 	}
-      end:
+end:
 	pr_debug(PREFIX "transaction end\n");
-	return result;
+	ec->t.command = 0;
+	if (test_bit(EC_FLAGS_GPE_STORM, &ec->flags)) {
+		/* check if we received SCI during transaction */
+		ec_check_sci(ec, acpi_ec_read_status(ec));
+		/* it is safe to enable GPE outside of transaction */
+		acpi_enable_gpe(NULL, ec->gpe, ACPI_NOT_ISR);
+	} else if (test_bit(EC_FLAGS_GPE_MODE, &ec->flags) &&
+		   atomic_read(&ec->irq_count) > ACPI_EC_STORM_THRESHOLD)
+		pr_debug(PREFIX "GPE storm detected\n");
+		set_bit(EC_FLAGS_GPE_STORM, &ec->flags);
+	return 0;
+}
+
+static int ec_check_ibf0(struct acpi_ec *ec)
+{
+	u8 status = acpi_ec_read_status(ec);
+	return (status & ACPI_EC_FLAG_IBF) == 0;
 }
 
 static int acpi_ec_transaction(struct acpi_ec *ec, u8 command,
@@ -299,8 +302,8 @@ static int acpi_ec_transaction(struct acpi_ec *ec, u8 command,
 		}
 	}
 
-	status = acpi_ec_wait(ec, ACPI_EC_EVENT_IBF_0, 0);
-	if (status) {
+	if (!wait_event_timeout(ec->wait, ec_check_ibf0(ec),
+				msecs_to_jiffies(ACPI_EC_DELAY))) {
 		pr_err(PREFIX "input buffer is not empty, "
 				"aborting transaction\n");
 		goto end;
@@ -437,6 +440,7 @@ static int acpi_ec_query(struct acpi_ec *ec, u8 * data)
 	 */
 
 	result = acpi_ec_transaction(ec, ACPI_EC_COMMAND_QUERY, NULL, 0, &d, 1, 0);
+	clear_bit(EC_FLAGS_QUERY_PENDING, &ec->flags);
 	if (result)
 		return result;
 
@@ -515,24 +519,17 @@ static u32 acpi_ec_gpe_handler(void *data)
 {
 	acpi_status status = AE_OK;
 	struct acpi_ec *ec = data;
-	u8 state = acpi_ec_read_status(ec);
+	u8 state;
 
 	pr_debug(PREFIX "~~~> interrupt\n");
-	atomic_inc(&ec->irq_count);
-	if (atomic_read(&ec->irq_count) > 5) {
-		pr_err(PREFIX "GPE storm detected, disabling EC GPE\n");
-		ec_switch_to_poll_mode(ec);
-		goto end;
-	}
-	clear_bit(EC_FLAGS_WAIT_GPE, &ec->flags);
-	if (test_bit(EC_FLAGS_GPE_MODE, &ec->flags))
+	state = acpi_ec_read_status(ec);
+
+	gpe_transaction(ec, state);
+	if ((status & ACPI_EC_FLAG_IBF) == 0)
 		wake_up(&ec->wait);
 
-	if (state & ACPI_EC_FLAG_SCI) {
-		if (!test_and_set_bit(EC_FLAGS_QUERY_PENDING, &ec->flags))
-			status = acpi_os_execute(OSL_EC_BURST_HANDLER,
-				acpi_ec_gpe_query, ec);
-	} else if (!test_bit(EC_FLAGS_GPE_MODE, &ec->flags) &&
+	status = ec_check_sci(ec, state);
+	if (!test_bit(EC_FLAGS_GPE_MODE, &ec->flags) &&
 		   !test_bit(EC_FLAGS_NO_GPE, &ec->flags) &&
 		   in_interrupt()) {
 		/* this is non-query, must be confirmation */
@@ -540,21 +537,11 @@ static u32 acpi_ec_gpe_handler(void *data)
 			pr_info(PREFIX "non-query interrupt received,"
 				" switching to interrupt mode\n");
 		set_bit(EC_FLAGS_GPE_MODE, &ec->flags);
-		clear_bit(EC_FLAGS_RESCHEDULE_POLL, &ec->flags);
 	}
-end:
-	ec_schedule_ec_poll(ec);
 	return ACPI_SUCCESS(status) ?
 	    ACPI_INTERRUPT_HANDLED : ACPI_INTERRUPT_NOT_HANDLED;
 }
 
-static void do_ec_poll(struct work_struct *work)
-{
-	struct acpi_ec *ec = container_of(work, struct acpi_ec, work.work);
-	atomic_set(&ec->irq_count, 0);
-	(void)acpi_ec_gpe_handler(ec);
-}
-
 /* --------------------------------------------------------------------------
                              Address Space Management
    -------------------------------------------------------------------------- */
@@ -696,7 +683,6 @@ static struct acpi_ec *make_acpi_ec(void)
 	mutex_init(&ec->lock);
 	init_waitqueue_head(&ec->wait);
 	INIT_LIST_HEAD(&ec->list);
-	INIT_DELAYED_WORK_DEFERRABLE(&ec->work, do_ec_poll);
 	atomic_set(&ec->irq_count, 0);
 	return ec;
 }
@@ -736,15 +722,8 @@ ec_parse_device(acpi_handle handle, u32 Level, void *context, void **retval)
 	return AE_CTRL_TERMINATE;
 }
 
-static void ec_poll_stop(struct acpi_ec *ec)
-{
-	clear_bit(EC_FLAGS_RESCHEDULE_POLL, &ec->flags);
-	cancel_delayed_work(&ec->work);
-}
-
 static void ec_remove_handlers(struct acpi_ec *ec)
 {
-	ec_poll_stop(ec);
 	if (ACPI_FAILURE(acpi_remove_address_space_handler(ec->handle,
 				ACPI_ADR_SPACE_EC, &acpi_ec_space_handler)))
 		pr_err(PREFIX "failed to remove space handler\n");
@@ -849,14 +828,12 @@ static int ec_install_handlers(struct acpi_ec *ec)
 	if (ec->handlers_installed)
 		return 0;
 	status = acpi_install_gpe_handler(NULL, ec->gpe,
-					  ACPI_GPE_EDGE_TRIGGERED,
-					  &acpi_ec_gpe_handler, ec);
+				  ACPI_GPE_EDGE_TRIGGERED,
+				  &acpi_ec_gpe_handler, ec);
 	if (ACPI_FAILURE(status))
 		return -ENODEV;
-
 	acpi_set_gpe_type(NULL, ec->gpe, ACPI_GPE_TYPE_RUNTIME);
 	acpi_enable_gpe(NULL, ec->gpe, ACPI_NOT_ISR);
-
 	status = acpi_install_address_space_handler(ec->handle,
 						    ACPI_ADR_SPACE_EC,
 						    &acpi_ec_space_handler,
@@ -887,7 +864,6 @@ static int acpi_ec_start(struct acpi_device *device)
 
 	/* EC is fully operational, allow queries */
 	clear_bit(EC_FLAGS_QUERY_PENDING, &ec->flags);
-	ec_schedule_ec_poll(ec);
 	return ret;
 }