On Wed, 10 Jun 2015, Russell King - ARM Linux wrote:
On Wed, Jun 10, 2015 at 01:07:08PM +0200, Nicholas Mc Guire wrote:
The calling side seems to assume 0 as success and <0 as error so returning -ETIME should be fine here.
The idea here is to allow the remainder of the code to execute when the condition succeeds _or_ times out. If it times out, that is not a failure - it merely means that the display has been blanked and we're not seeing frame done interrupts anymore.
The code should not be checking the returned value at all - in fact I have updates to this code which (in part) remove this, and fix a glaring problem that the wait queue is never woken.
I wonder how many places you've made this same mistake... please ensure that you review the code you're changing carefully.
Sorry for that - I do try my best to understand the code - my obviously wrong understanding of the code was that a negative return was being expected as being possible and then handed back to the caller so I assumed that would be the timeout case - but as this can never happen it was basically ignoring the timeout - that the execution should continue in the case of timeout being reached was not clear to me (it might be worth a comment ?)
I did find similar cases in other drivers ./drivers/media/platform/s5p-tv/mixer_reg.c:364 incorrect check for negative return checking for < 0 and returning (so unreachable return statement with no effect but no side-effect in that condition ither) or ./drivers/media/pci/ddbridge/ddbridge-core.c:89 incorrect check for negative return which checked for <= 0 and was fixed up to == 0 which is correct as the < 0 case simply is unreachable - so no change of error handling logic.
but those two other cases I think are correctly fixed up.
thx! hofrat