On 07/30/2012 09:44 AM, Rob Herring wrote: > On 07/27/2012 07:05 AM, Alexandre Courbot wrote: >> Some device drivers (panel backlights especially) need to follow precise >> sequences for powering on and off, involving gpios, regulators, PWMs >> with a precise powering order and delays to respect between each steps. >> These sequences are board-specific, and do not belong to a particular >> driver - therefore they have been performed by board-specific hook >> functions to far. >> >> With the advent of the device tree and of ARM kernels that are not >> board-tied, we cannot rely on these board-specific hooks anymore but >> need a way to implement these sequences in a portable manner. This patch >> introduces a simple interpreter that can execute such power sequences >> encoded either as platform data or within the device tree. >> > > Why not? We'll always have some amount of board code. The key is to > limit parts that are just data. I'm not sure this is something that > should be in devicetree. > > Perhaps what is needed is a better way to hook into the driver like > notifiers? I would answer that by asking the reverse question - why should we have to put some data in DT, and some data into board files still? I'd certainly argue that the sequence of which GPIOs/regulators/PWMs to manipulate is just data. To be honest, if we're going to have to put some parts of a board's configuration into board files anyway, then the entirety of DT seems useless; I'd far rather see all the configuration in one cohesive place than arbitrarily split into two/n different locations - that would make everything harder to maintain. -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
