[PATCH] ARM: imx25-pinfunc: remove SION from all modes

Lothar Waßmann LW at KARO-electronics.de
Wed Apr 20 01:46:17 PDT 2016


On Tue, 19 Apr 2016 22:19:58 +0100 Russell King - ARM Linux wrote:
> On Tue, Apr 19, 2016 at 09:45:14PM +0200, Uwe Kleine-König wrote:
> > With the SION bit set a pin can be read as GPIO even though it's not muxed
> > as GPIO. This is useful at times. The downside however is that the signal
> > is not only routed to the GPIO IP but also all other IPs that can make use
> > of the pin. This resulted in more than one issue for me in the past. Things
> > like spi transfers that result in usb reenumeration or setting a GPIO to a
> > value that triggers an RTS irq for an UART.
> Isn't SION required for all GPIOs such that reading the value of a GPIO
> pin returns the actual state of the pin, not the output value written
> to it?
> What about the ethernet pins?  I know that on iMX6, SION is required for
> correct functionality of certain phy clocking modes, and I wouldn't be
> surprised if this was true in earlier designs as well.
SION essentially makes any OUTPUT pin (GPIO or other function)

Lothar Waßmann

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