[PATCH v1] mfd: tps6586x: Move interrupt handling into workqueue

[Dmitry Osipenko]

Reading of status register within the interrupt handler fails with -EAGAIN
if I2C is busy with handling some other request at the same time. Move the
actual interrupt handling into a workqueue to avoid the unfortunate I2C
failure and to avoid hanging CPU in interrupt up to 1 second (transfer
timeout in the Tegra I2C driver).

Signed-off-by: Dmitry Osipenko <dig...@gmail.com>
---
 drivers/mfd/tps6586x.c | 40 +++++++++++++++++++++++++++++-----------
 1 file changed, 29 insertions(+), 11 deletions(-)

diff --git a/drivers/mfd/tps6586x.c b/drivers/mfd/tps6586x.c
index b89379782741..9896e080b274 100644
--- a/drivers/mfd/tps6586x.c
+++ b/drivers/mfd/tps6586x.c
@@ -133,6 +133,7 @@ struct tps6586x {
        u32                     irq_en;
        u8                      mask_reg[5];
        struct irq_domain       *irq_domain;
+       struct work_struct      isr_work;
 };
 
 static inline struct tps6586x *dev_to_tps6586x(struct device *dev)
@@ -309,18 +310,19 @@ static const struct irq_domain_ops tps6586x_domain_ops = {
        .xlate  = irq_domain_xlate_twocell,
 };
 
-static irqreturn_t tps6586x_irq(int irq, void *data)
+static void tps6586x_isr_work(struct work_struct *work)
 {
-       struct tps6586x *tps6586x = data;
+       struct tps6586x *tps6586x = container_of(work, struct tps6586x,
+                                                isr_work);
        u32 acks;
-       int ret = 0;
+       int err;
 
-       ret = tps6586x_reads(tps6586x->dev, TPS6586X_INT_ACK1,
+       err = tps6586x_reads(tps6586x->dev, TPS6586X_INT_ACK1,
                             sizeof(acks), (uint8_t *)&acks);
-
-       if (ret < 0) {
-               dev_err(tps6586x->dev, "failed to read interrupt status\n");
-               return IRQ_NONE;
+       if (err < 0) {
+               dev_err(tps6586x->dev,
+                       "failed to read interrupt status %d\n", err);
+               return;
        }
 
        acks = le32_to_cpu(acks);
@@ -335,6 +337,16 @@ static irqreturn_t tps6586x_irq(int irq, void *data)
                acks &= ~(1 << i);
        }
 
+       enable_irq(tps6586x->irq);
+}
+
+static irqreturn_t tps6586x_irq(int irq, void *data)
+{
+       struct tps6586x *tps6586x = data;
+
+       disable_irq_nosync(irq);
+       schedule_work(&tps6586x->isr_work);
+
        return IRQ_HANDLED;
 }
 
@@ -542,8 +554,9 @@ static int tps6586x_i2c_probe(struct i2c_client *client,
                return ret;
        }
 
-
        if (client->irq) {
+               INIT_WORK(&tps6586x->isr_work, tps6586x_isr_work);
+
                ret = tps6586x_irq_init(tps6586x, client->irq,
                                        pdata->irq_base);
                if (ret) {
@@ -585,10 +598,15 @@ static int tps6586x_i2c_remove(struct i2c_client *client)
 {
        struct tps6586x *tps6586x = i2c_get_clientdata(client);
 
+       if (client->irq) {
+               disable_irq(client->irq);
+               flush_work(&tps6586x->isr_work);
+               free_irq(client->irq, tps6586x);
+       }
+
        tps6586x_remove_subdevs(tps6586x);
        mfd_remove_devices(tps6586x->dev);
-       if (client->irq)
-               free_irq(client->irq, tps6586x);
+
        return 0;
 }
 
-- 
2.17.0