i2c: rk3x: fix potential spinlock recursion on poll

Possible deadlock scenario (on reboot):
rk3x_i2c_xfer_common(polling)
    -> rk3x_i2c_wait_xfer_poll()
        -> rk3x_i2c_irq(0, i2c);
            --> spin_lock(&i2c->lock);
            ...
        <rk3x i2c interrupt>
        -> rk3x_i2c_irq(0, i2c);
            --> spin_lock(&i2c->lock); (deadlock here)

Store the IRQ number and disable/enable it around the polling transfer.
This patch has been tested on NanoPC-T4.

Signed-off-by: Jensen Huang <jensenhuang@friendlyarm.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Andi Shyti <andi.shyti@kernel.org>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

diff --git a/drivers/i2c/busses/i2c-rk3x.c b/drivers/i2c/busses/i2c-rk3x.c
index a044ca0c35a193e9f8abeb3cff88707285a7028d..4362db7c57892c83d53f3c0062630d7b7b7d9990 100644 (file)
--- a/drivers/i2c/busses/i2c-rk3x.c
+++ b/drivers/i2c/busses/i2c-rk3x.c
@@ -178,6 +178,7 @@ struct rk3x_i2c_soc_data {
  * @clk: function clk for rk3399 or function & Bus clks for others
  * @pclk: Bus clk for rk3399
  * @clk_rate_nb: i2c clk rate change notify
+ * @irq: irq number
  * @t: I2C known timing information
  * @lock: spinlock for the i2c bus
  * @wait: the waitqueue to wait for i2c transfer
@@ -200,6 +201,7 @@ struct rk3x_i2c {
        struct clk *clk;
        struct clk *pclk;
        struct notifier_block clk_rate_nb;
+       int irq;
 
        /* Settings */
        struct i2c_timings t;
@@ -1087,13 +1089,18 @@ static int rk3x_i2c_xfer_common(struct i2c_adapter *adap,
 
                spin_unlock_irqrestore(&i2c->lock, flags);
 
-               rk3x_i2c_start(i2c);
-
                if (!polling) {
+                       rk3x_i2c_start(i2c);
+
                        timeout = wait_event_timeout(i2c->wait, !i2c->busy,
                                                     msecs_to_jiffies(WAIT_TIMEOUT));
                } else {
+                       disable_irq(i2c->irq);
+                       rk3x_i2c_start(i2c);
+
                        timeout = rk3x_i2c_wait_xfer_poll(i2c);
+
+                       enable_irq(i2c->irq);
                }
 
                spin_lock_irqsave(&i2c->lock, flags);
@@ -1310,6 +1317,8 @@ static int rk3x_i2c_probe(struct platform_device *pdev)
                return ret;
        }
 
+       i2c->irq = irq;
+
        platform_set_drvdata(pdev, i2c);
 
        if (i2c->soc_data->calc_timings == rk3x_i2c_v0_calc_timings) {