On Fri, 2016-08-05 at 08:58 +0200, Uwe Kleine-K?nig wrote:

On Fri, Aug 05, 2016 at 12:44:23AM +0200, Christoph Fritz wrote:

quoted

here on a imx6sx board newly introduced DSR-irq-handling breaks serial
console and network support.

Reverting commit 27e16501052e5341934d3 "serial: imx: implement DSR irq
handling for DTE mode" fixes the issue.

The underlying cause is the RMII network configuration where register
bit SION in IOMUXC_SW_MUX_CTL_PAD_ENET1_TX_CLK is necessary. But this
also falsely feeds signal UART1_DTR_B and triggers DSR irq...

Can we revert this commit or add a quirk for RMII-SION configs or make
this optional by a device tree option?

Hmm, MX6SX_PAD_ENET1_TX_CLK__ENET1_TX_CLK in
arch/arm/boot/dts/imx6sx-pinfunc.h doesn't have SION set.

I remember there were issues around eth and SION on i.MX6DL, but don't
know the details. A quick net research found
https://community.nxp.com/thread/359531 which has: "Set the SION bit.
Note that this is not required because the funtion setting controls the
signal path, but it is good practice as it reminds the user that the
clock needs to fed back into the Ethernet MAC.". Sounds like dangerous
smattering and a wrong expectation about "users".

https://community.nxp.com/thread/376821 is from someone who has the same
problem(?) on i.MX6SX, but no solution yet.

Does that mean MX6SX_PAD_ENET1_TX_CLK__ENET1_TX_CLK always needs the
SION bit set?

SION is necessary for pinconfig MX6SX_PAD_ENET1_TX_CLK__ENET1_REF_CLK1
if bit 17 in IOMUXC_GPR_GPR1 is set and bit 13 not.

So that ref_enetpll1 provides a clock not only for the external PHY but
also for the internal controller.

Using SION is a quirk here, because the silicon doesn't feed the clock
back to the internal controller automatically.

On the other hand, NXP could argue: You need to add a wire on your PCB
between ENET1_REF_CLK1 and ENET1_TX_CLK -- but referring to the
datasheet ENET1_TX_CLK isn't used in RMII config...

So if Fabio or Shawn agrees with my assumption above, I'll add something
like 27e16501052e5341934d3 "serial: imx: implement DSR irq
handling for DTE mode".

Okay?