Re: [PATCH v2 1/4] i2c: qcom-cci: Fix ordering of pm_runtime_xx and i2c_add_adapter

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Hi Bryan,

On 5/24/22 17:02, Bryan O'Donoghue wrote:
When we compile-in the CCI along with the imx412 driver and run on the RB5
we see that i2c_add_adapter() causes the probe of the imx412 driver to
happen.

This probe tries to perform an i2c xfer() and the xfer() in i2c-qcom-cci.c
fails on pm_runtime_get() because the i2c-qcom-cci.c::probe() function has
not completed to pm_runtime_enable(dev).

Fix this sequence by ensuring pm_runtime_xxx() calls happen prior to adding
the i2c adapter.


it's a proper root cause disclosure and the fix, thank you.

Fixes: e517526195de ("i2c: Add Qualcomm CCI I2C driver")
Reported-by: Vladimir Zapolskiy <vladimir.zapolskiy@xxxxxxxxxx>
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@xxxxxxxxxx>
---
  drivers/i2c/busses/i2c-qcom-cci.c | 14 +++++++++-----
  1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/i2c/busses/i2c-qcom-cci.c b/drivers/i2c/busses/i2c-qcom-cci.c
index 5c7cc862f08f..90d02effeae9 100644
--- a/drivers/i2c/busses/i2c-qcom-cci.c
+++ b/drivers/i2c/busses/i2c-qcom-cci.c
@@ -638,6 +638,11 @@ static int cci_probe(struct platform_device *pdev)
  	if (ret < 0)
  		goto error;
+ pm_runtime_set_autosuspend_delay(dev, MSEC_PER_SEC);
+	pm_runtime_use_autosuspend(dev);
+	pm_runtime_set_active(dev);
+	pm_runtime_enable(dev);
+
  	for (i = 0; i < cci->data->num_masters; i++) {
  		if (!cci->master[i].cci)
  			continue;
@@ -649,14 +654,13 @@ static int cci_probe(struct platform_device *pdev)
  		}
  	}
- pm_runtime_set_autosuspend_delay(dev, MSEC_PER_SEC);
-	pm_runtime_use_autosuspend(dev);
-	pm_runtime_set_active(dev);
-	pm_runtime_enable(dev);
-
  	return 0;
error_i2c:
+	pm_runtime_put(dev);

Here pm_runtime_put(dev) should be removed, there is no pm_runtime_get*(dev) above,
otherwise PM usage counter underflow issues are expected.

+	pm_runtime_disable(dev);
+	pm_runtime_dont_use_autosuspend(dev);
+
  	for (--i ; i >= 0; i--) {
  		if (cci->master[i].cci) {
  			i2c_del_adapter(&cci->master[i].adap);

With the correction stated above please feel free to add my tags:

Reviewed-by: Vladimir Zapolskiy <vladimir.zapolskiy@xxxxxxxxxx>
Tested-by: Vladimir Zapolskiy <vladimir.zapolskiy@xxxxxxxxxx>

--
Best wishes,
Vladimir



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