[RFC] ACPI: EC: Merge poll and interrupt modes

In general, EC transaction should complete in less than 1ms, thus it is 
possible to merge wait for
1ms in poll mode and 1ms of interrupt transaction timeout.
Still, driver will wait 500ms for EC to complete transaction.

This significantly simplifies driver and makes it immune to problematic 
EC interrupt
implementations.

It also may lessen kernel start-up time by 500ms.

References: http://bugzilla.kernel.org/show_bug.cgi?id=12949

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

 drivers/acpi/ec.c |  125 
+++++++++++++++++++----------------------------------
 1 files changed, 45 insertions(+), 80 deletions(-)


     ec->curr = NULL;
@@ -285,8 +266,7 @@ static int acpi_ec_transaction_unlocked(struct 
acpi_ec *ec,
         ec_check_sci(ec, acpi_ec_read_status(ec));
         /* it is safe to enable GPE outside of transaction */
         acpi_enable_gpe(NULL, ec->gpe);
-    } else if (test_bit(EC_FLAGS_GPE_MODE, &ec->flags) &&
-           t->irq_count > ACPI_EC_STORM_THRESHOLD) {
+    } else if (t->irq_count > ACPI_EC_STORM_THRESHOLD) {
         pr_info(PREFIX "GPE storm detected, "
             "transactions will use polling mode\n");
         set_bit(EC_FLAGS_GPE_STORM, &ec->flags);
@@ -304,16 +284,14 @@ static int ec_wait_ibf0(struct acpi_ec *ec)
 {
     unsigned long delay = jiffies + msecs_to_jiffies(ACPI_EC_DELAY);
     /* interrupt wait manually if GPE mode is not active */
-    unsigned long timeout = test_bit(EC_FLAGS_GPE_MODE, &ec->flags) ?
-        msecs_to_jiffies(ACPI_EC_DELAY) : msecs_to_jiffies(1);
     while (time_before(jiffies, delay))
-        if (wait_event_timeout(ec->wait, ec_check_ibf0(ec), timeout))
+        if (wait_event_timeout(ec->wait, ec_check_ibf0(ec),
+                    msecs_to_jiffies(1)))
             return 0;
     return -ETIME;
 }
 
-static int acpi_ec_transaction(struct acpi_ec *ec, struct transaction *t,
-                   int force_poll)
+static int acpi_ec_transaction(struct acpi_ec *ec, struct transaction *t)
 {
     int status;
     u32 glk;
@@ -335,7 +313,7 @@ static int acpi_ec_transaction(struct acpi_ec *ec, 
struct transaction *t,
         status = -ETIME;
         goto end;
     }
-    status = acpi_ec_transaction_unlocked(ec, t, force_poll);
+    status = acpi_ec_transaction_unlocked(ec, t);
 end:
     if (ec->global_lock)
         acpi_release_global_lock(glk);
@@ -355,7 +333,7 @@ static int acpi_ec_burst_enable(struct acpi_ec *ec)
                 .wdata = NULL, .rdata = &d,
                 .wlen = 0, .rlen = 1};
 
-    return acpi_ec_transaction(ec, &t, 0);
+    return acpi_ec_transaction(ec, &t);
 }
 
 static int acpi_ec_burst_disable(struct acpi_ec *ec)
@@ -365,7 +343,7 @@ static int acpi_ec_burst_disable(struct acpi_ec *ec)
                 .wlen = 0, .rlen = 0};
 
     return (acpi_ec_read_status(ec) & ACPI_EC_FLAG_BURST) ?
-                acpi_ec_transaction(ec, &t, 0) : 0;
+                acpi_ec_transaction(ec, &t) : 0;
 }
 
 static int acpi_ec_read(struct acpi_ec *ec, u8 address, u8 * data)
@@ -376,7 +354,7 @@ static int acpi_ec_read(struct acpi_ec *ec, u8 
address, u8 * data)
                 .wdata = &address, .rdata = &d,
                 .wlen = 1, .rlen = 1};
 
-    result = acpi_ec_transaction(ec, &t, 0);
+    result = acpi_ec_transaction(ec, &t);
     *data = d;
     return result;
 }
@@ -388,7 +366,7 @@ static int acpi_ec_write(struct acpi_ec *ec, u8 
address, u8 data)
                 .wdata = wdata, .rdata = NULL,
                 .wlen = 2, .rlen = 0};
 
-    return acpi_ec_transaction(ec, &t, 0);
+    return acpi_ec_transaction(ec, &t);
 }
 
 /*
@@ -456,7 +434,7 @@ int ec_transaction(u8 command,
     if (!first_ec)
         return -ENODEV;
 
-    return acpi_ec_transaction(first_ec, &t, force_poll);
+    return acpi_ec_transaction(first_ec, &t);
 }
 
 EXPORT_SYMBOL(ec_transaction);
@@ -477,7 +455,7 @@ static int acpi_ec_query(struct acpi_ec *ec, u8 * data)
      * bit to be cleared (and thus clearing the interrupt source).
      */
 
-    result = acpi_ec_transaction(ec, &t, 0);
+    result = acpi_ec_transaction(ec, &t);
     if (result)
         return result;
 
@@ -560,27 +538,19 @@ static u32 acpi_ec_gpe_handler(void *data)
     pr_debug(PREFIX "~~~> interrupt\n");
     status = acpi_ec_read_status(ec);
 
-    if (test_bit(EC_FLAGS_GPE_MODE, &ec->flags)) {
-        gpe_transaction(ec, status);
-        if (ec_transaction_done(ec) &&
-            (status & ACPI_EC_FLAG_IBF) == 0)
-            wake_up(&ec->wait);
-    }
-
+    advance_transaction(ec, status);
+    if (ec_transaction_done(ec) && (status & ACPI_EC_FLAG_IBF) == 0)
+        wake_up(&ec->wait);
     ec_check_sci(ec, status);
-    if (!test_bit(EC_FLAGS_GPE_MODE, &ec->flags) &&
-        !test_bit(EC_FLAGS_NO_GPE, &ec->flags)) {
-        /* this is non-query, must be confirmation */
-        if (!test_bit(EC_FLAGS_GPE_STORM, &ec->flags)) {
-            if (printk_ratelimit())
-                pr_info(PREFIX "non-query interrupt received,"
-                    " switching to interrupt mode\n");
-        } else {
-            /* hush, STORM switches the mode every transaction */
-            pr_debug(PREFIX "non-query interrupt received,"
+    /* this is non-query, must be confirmation */
+    if (!test_bit(EC_FLAGS_GPE_STORM, &ec->flags)) {
+        if (printk_ratelimit())
+            pr_info(PREFIX "non-query interrupt received,"
                 " switching to interrupt mode\n");
-        }
-        set_bit(EC_FLAGS_GPE_MODE, &ec->flags);
+    } else {
+        /* hush, STORM switches the mode every transaction */
+        pr_debug(PREFIX "non-query interrupt received,"
+            " switching to interrupt mode\n");
     }
     return ACPI_INTERRUPT_HANDLED;
 }
@@ -823,8 +793,6 @@ static int acpi_ec_add(struct acpi_device *device)
     acpi_ec_add_fs(device);
     pr_info(PREFIX "GPE = 0x%lx, I/O: command/status = 0x%lx, data = 
0x%lx\n",
               ec->gpe, ec->command_addr, ec->data_addr);
-    pr_info(PREFIX "driver started in %s mode\n",
-        (test_bit(EC_FLAGS_GPE_MODE, &ec->flags))?"interrupt":"poll");
     return 0;
 }
 
@@ -1040,8 +1008,6 @@ static int acpi_ec_suspend(struct acpi_device 
*device, pm_message_t state)
 {
     struct acpi_ec *ec = acpi_driver_data(device);
     /* Stop using GPE */
-    set_bit(EC_FLAGS_NO_GPE, &ec->flags);
-    clear_bit(EC_FLAGS_GPE_MODE, &ec->flags);
     acpi_disable_gpe(NULL, ec->gpe);
     return 0;
 }
@@ -1050,7 +1016,6 @@ static int acpi_ec_resume(struct acpi_device *device)
 {
     struct acpi_ec *ec = acpi_driver_data(device);
     /* Enable use of GPE back */
-    clear_bit(EC_FLAGS_NO_GPE, &ec->flags);
     acpi_enable_gpe(NULL, ec->gpe);
     return 0;
 }

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[RFC] ACPI: EC: Merge poll and interrupt modes

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