On 11/01/2012 03:35 PM, Mark Brown wrote:
is a very nice power saving feature. I just cache all the register settings up until that point (which required a bit of coding because of the "paging" of the I2C address space).
Probably easiest to just convert over to regmap, it handles paging fine.
I've backported the driver to 2.6.37 so probably my regmap wasn't smart enough yet.
It was the best I could think off at the time, and it made me wonder why those reset lines aren't modelled this way more often.
This breaks down if any of the drivers actually uses the reset pin to reset the chip - if the reset might not actually happen but the driver wants it to happen then things are going to go wrong.
Good point. But in that case, the gpio cannot be "optional", the board file MUST supply it.
Most chips - if not all, and this one certainly has it - also have a software routine for resetting it.
From a hardware perspective, when using two codecs to get a 4-channel input, it makes perfect sense to use the same GPIO line to reset them both. This will never work with two instances of a driver that wants to control the GPIO line directly, but it works flawlessly when that line is modelled as a power supply. Each instance can request the reset to be relaxed, and each instance gets feedback from the supply core when the reset line is actually being altered (which can for example be used to update the codec's registers from the cache, or to indicate that the chip is no longer online and every write must go to the cache only).
Do I understand correctly that I'm totally alone in this and that there is no point in uploading the code?
Met vriendelijke groet / kind regards,
Mike Looijmans
TOPIC Embedded Systems Eindhovenseweg 32-C, NL-5683 KH Best Postbus 440, NL-5680 AK Best Telefoon: (+31) – (0)499 - 33.69.79 Telefax: (+31) - (0)499 - 33.69.70 E-mail: mike.looijmans@topic.nl Website: www.topic.nl
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