Re: [PATCH 2/5] i2c: omap: add runtime check in isr to be sure thati2c is enabled

From: Grygorii Strashko
Date: Wed Jun 19 2013 - 14:49:19 EST

Hi Felipe,
On 06/07/2013 10:02 PM, Felipe Balbi wrote:

On Fri, Jun 07, 2013 at 09:46:05PM +0300, Grygorii Strashko wrote:
Add runtime check at the beginning of omap_i2c_isr/omap_i2c_isr_thread
to be sure that i2c is enabled, before performing IRQ handling and accessing
I2C IP registers:
if (pm_runtime_suspended(dev->dev)) {
WARN_ONCE(true, "We should never be here!\n");
return IRQ_NONE;

Produce warning in case if ISR called when i2c is disabled

CC: Kevin Hilman <khilman@xxxxxxxxxx>
Signed-off-by: Grygorii Strashko <grygorii.strashko@xxxxxx>
drivers/i2c/busses/i2c-omap.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index 97844ff..2dac598 100644
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -885,6 +885,11 @@ omap_i2c_isr(int irq, void *dev_id)
u16 stat;
+ if (pm_runtime_suspended(dev->dev)) {
+ WARN_ONCE(true, "We should never be here!\n");
+ return IRQ_NONE;
+ }
returning IRQ_NONE is not what you want to do in this case. You want to
setup a flag so that your runtime_resume() knows that there are pending
events to be handled and you handle those in runtime_resume time.
I don't want to handle this IRQ - we should never be here.
Will be changed to IRQ_HANDLED.

But to be frank, I don't see how this can trigger since we're calling
pm_runtime_get_sync() from omap_i2c_xfer() which means by the time
pm_runtime_get_sync() returns, assuming no errors, i2c module should be
fully resumed and ready to go. Perhaps you have found a bug somewhere
else ?
May be it's better to revert this patch:
i2c: omap: remove unnecessary pm_runtime_suspended check

which doesn't cover case when transfer is *finished*.
Please, see and

Also, your 'We should never be here' message isn't helpfull at all.

@@ -905,6 +910,11 @@ omap_i2c_isr_thread(int this_irq, void *dev_id)
u16 stat;
int err = 0, count = 0;
+ if (pm_runtime_suspended(dev->dev)) {
+ WARN_ONCE(true, "We should never be here!\n");
+ return IRQ_NONE;
+ }
because of IRQF_ONESHOT I can't see how this would *ever* be a valid

Please, see and

Sorry, for delayed reply - I've had problems with my e-mail.

- grygorii
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