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>

diff --git a/drivers/power/ab8500_fg.c b/drivers/power/ab8500_fg.c
index 40344e0..d30387b 100644 (file)
--- 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;