Hi,
On Mon, Feb 6, 2017 at 4:03 AM, Thierry Reding thierry.reding@gmail.com wrote:
On Thu, Feb 02, 2017 at 03:38:53PM -0800, Douglas Anderson wrote:
The Sharp lq123p1jx31 has a requirement that the VDD is on for at least 300 ms before being turned off. At the moment nothing anywhere in the kernel is ensuring this.
Looks to me like .delay.prepare would be a better fit. That enables the regulator and setting it to 300 ms would make sure that the regulator will always get enabled for at least 300 ms.
This would also ensure that the 300 ms wasn't violated, right.
Anyway, your commit message says nothing about why this is important. What are the side-effects if the above isn't true? Does the display hang in some way?
See my own response where I NAKed my own patch because I realized that it wasn't fixing the root cause of the problem I was seeing (it just happened to push timing around). Basically the problem was that the backlight was getting turned on while the panel was off and the panel didn't like that. This appears to already be addressed with upstream patches, so picking those into my tree fixed the problem.
It might be nice long term to address some of these "the panel needs to be on for at least 300 ms" or "the panel needs to be off for at least 500 ms" in a way that doesn't require a hardcoded delay.
I suppose it could be done today with a custom panel driver, so I guess it depends on how common those types of requirements are in the spec and how important they are to actually follow.
-Doug