On Wed, Feb 06, 2019 at 11:32:31AM +0800, Chen-Yu Tsai wrote: > The A80 SoC has configuration registers for I/O bias voltage. Incorrect > settings would make the affected peripherals inoperable in some cases, > such as Ethernet RGMII signals biased at 2.5V with the settings still > at 3.3V. However low speed signals such as MDIO on the same group of > pins seem to be unaffected. > > Previously there was no way to know what the actual voltage used was, > short of hard-coding a value in the device tree. With the new pin bank > regulator supply support in place, the driver can now query the > regulator for its voltage, and if it's valid (as opposed to being the > dummy regulator), set the bias voltage setting accordingly. > > Add a quirk to denote the presence of the configuration registers, and > a function to set the correct setting based on the voltage read back > from the regulator. > > This is only done when the regulator is first acquired and enabled. > While it would be nice to have a notifier on the regulator so that when > the voltage changes, the driver can update the setting, in practice no > board currently supports dynamic changing of the I/O voltages. > > Signed-off-by: Chen-Yu Tsai <wens@xxxxxxxx> Acked-by: Maxime Ripard <maxime.ripard@xxxxxxxxxxx> Maxime -- Maxime Ripard, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
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