On Wednesday 25 May 2016 10:25:29, Meng Yi wrote:
Hi Alexander, Thanks for your reply.
Commit d761701c55a99598477f3cb25c03d939a7711e74 only has one child commit in my repo. Both touch only i915 related things. Please do a proper bisect and name the offending commit. On which commit you got that backtrace BTW? From your backtrace I can't see anything related to regmap.
It is weird that using bisect, for the commit log is not linear. I mean a newer date commit may be merged before an older date commit, when jump to that older date commit, the newer one will be lost, even though it is merged before older one. So, I think it's difficult to use git bisect. " d761701c55a99598477f3cb25c03d939a7711e74 " is just an older one, I mean between this commit and the next commit, maybe lots of commits are lost. So, it looks like this commit have nothing to do with the problem.
Why are commits lost? The order of commit dates is not straightforward, yes, but that's not a problem at all.
According to the backtrace, looks like the vblank interrupt is not happen or handled. Then I found the irq is installed successfully, so the problem seems like the vblank irq is not properly setup. And here is the point , irq initia, irq handler and timing control code are using regmap.
From your backtrace I guess wait_event_timeout is called in some atomic
context (might_sleep(); is called inside wait_event_timeout). This has nothing to do with regmap.
I read out the value of relevant register using "CodeWarrior TAP", find that endianness is not right.
Then I changed endianness of the value to be written that using " regmap_write" . It works. But "regmap_update_bits" still have the problem.
I had checked log of regmap, and didn't find which commit caused that.
The inital problem came up with 922a9f936e40001f9b921379aab90047d5990923 ("regmap: mmio: Convert to regmap_bus and fix accessor usage"). The commits 9f9f8b863ad130ec0c25f378bdbad64ba71291de, 4f7d6dd4df8b388e2056c89b528254cdd79dea2a and 0dbdb76c0ca8e7caf27c9a210f64c4359e2974a4 tried to fix that. With those I could successfully probe DCU.
Best regards, Alexander