ab8500_fg.c: only request threaded IRQs when necessary

All 5 IRQ handlers of the driver are requested as threaded interrupt
handlers.  However, only 1 handler can block.  The remaining 4 handlers
defer the actual handling to a workqueue.  Hence, 4 of 5 IRQ handlers
have a considerable overhead, since they are executed in a kernel thread
to schedule another kernel thread (workqueue).

This change splits up the 5 interrupt handlers into top halves (_th) and
bottom halves (_bh) and resolves the aforementioned overhead by only
requesting threaded interrupts (i.e., bottom halves) when necessary.

Signed-off-by: Valentin Rothberg <Valentin.Rothberg@lip6.fr>
Signed-off-by: Sebastian Reichel <sre@kernel.org>

1 files changed, 33 insertions, 13 deletions

diff --git a/drivers/power/ab8500_fg.c b/drivers/power/ab8500_fg.c
index 40344e01df80..d30387bc4c21 100644
--- a/drivers/power/ab8500_fg.c
+++ b/drivers/power/ab8500_fg.c
@@ -3055,11 +3055,14 @@ static int ab8500_fg_remove(struct platform_device *pdev)
 }
 
 /* ab8500 fg driver interrupts and their respective isr */
-static struct ab8500_fg_interrupts ab8500_fg_irq[] = {
+static struct ab8500_fg_interrupts ab8500_fg_irq_th[] = {
         {"NCONV_ACCU", ab8500_fg_cc_convend_handler},
         {"BATT_OVV", ab8500_fg_batt_ovv_handler},
         {"LOW_BAT_F", ab8500_fg_lowbatf_handler},
         {"CC_INT_CALIB", ab8500_fg_cc_int_calib_handler},
+};
+
+static struct ab8500_fg_interrupts ab8500_fg_irq_bh[] = {
         {"CCEOC", ab8500_fg_cc_data_end_handler},
 };
 
@@ -3187,21 +3190,36 @@ static int ab8500_fg_probe(struct platform_device *pdev)
         init_completion(&di->ab8500_fg_started);
         init_completion(&di->ab8500_fg_complete);
 
-        /* Register interrupts */
-        for (i = 0; i < ARRAY_SIZE(ab8500_fg_irq); i++) {
-                irq = platform_get_irq_byname(pdev, ab8500_fg_irq[i].name);
-                ret = request_threaded_irq(irq, NULL, ab8500_fg_irq[i].isr,
-                        IRQF_SHARED | IRQF_NO_SUSPEND,
-                        ab8500_fg_irq[i].name, di);
+        /* Register primary interrupt handlers */
+        for (i = 0; i < ARRAY_SIZE(ab8500_fg_irq_th); i++) {
+                irq = platform_get_irq_byname(pdev, ab8500_fg_irq_th[i].name);
+                ret = request_irq(irq, ab8500_fg_irq_th[i].isr,
+                                  IRQF_SHARED | IRQF_NO_SUSPEND,
+                                  ab8500_fg_irq_th[i].name, di);
 
                 if (ret != 0) {
-                        dev_err(di->dev, "failed to request %s IRQ %d: %d\n"
-                                , ab8500_fg_irq[i].name, irq, ret);
+                        dev_err(di->dev, "failed to request %s IRQ %d: %d\n",
+                                ab8500_fg_irq_th[i].name, irq, ret);
                         goto free_irq;
                 }
                 dev_dbg(di->dev, "Requested %s IRQ %d: %d\n",
-                        ab8500_fg_irq[i].name, irq, ret);
+                        ab8500_fg_irq_th[i].name, irq, ret);
         }
+
+        /* Register threaded interrupt handler */
+        irq = platform_get_irq_byname(pdev, ab8500_fg_irq_bh[0].name);
+        ret = request_threaded_irq(irq, NULL, ab8500_fg_irq_bh[0].isr,
+                                IRQF_SHARED | IRQF_NO_SUSPEND | IRQF_ONESHOT,
+                        ab8500_fg_irq_bh[0].name, di);
+
+        if (ret != 0) {
+                dev_err(di->dev, "failed to request %s IRQ %d: %d\n",
+                        ab8500_fg_irq_bh[0].name, irq, ret);
+                goto free_irq;
+        }
+        dev_dbg(di->dev, "Requested %s IRQ %d: %d\n",
+                ab8500_fg_irq_bh[0].name, irq, ret);
+
         di->irq = platform_get_irq_byname(pdev, "CCEOC");
         disable_irq(di->irq);
         di->nbr_cceoc_irq_cnt = 0;
@@ -3238,11 +3256,13 @@ static int ab8500_fg_probe(struct platform_device *pdev)
 free_irq:
         power_supply_unregister(&di->fg_psy);
 
-        /* We also have to free all successfully registered irqs */
-        for (i = i - 1; i >= 0; i--) {
-                irq = platform_get_irq_byname(pdev, ab8500_fg_irq[i].name);
+        /* We also have to free all registered irqs */
+        for (i = 0; i < ARRAY_SIZE(ab8500_fg_irq_th); i++) {
+                irq = platform_get_irq_byname(pdev, ab8500_fg_irq_th[i].name);
                 free_irq(irq, di);
         }
+        irq = platform_get_irq_byname(pdev, ab8500_fg_irq_bh[0].name);
+        free_irq(irq, di);
 free_inst_curr_wq:
         destroy_workqueue(di->fg_wq);
         return ret;