MIPS: Octeon: Fix CN6880 hang on XAUI init

Some CN68XX series Octeon II chips seem to hang if a reset is issued on
XAUI initialization. Avoid the hang by disabling the reset on affected
models. Tested on Cavium EBB6800 evaluation board and Kontron S1901 board.

Signed-off-by: Janne Huttunen <janne.huttunen@nokia.com>
Signed-off-by: Aaro Koskinen <aaro.koskinen@nokia.com>
Acked-by: David Daney <david.daney@cavium.com>
Cc: David Daney <ddaney.cavm@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: Janne Huttunen <janne.huttunen@nokia.com>
Cc: Aaro Koskinen <aaro.koskinen@nokia.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: devel@driverdev.osuosl.org
Patchwork: http://patchwork.linux-mips.org/patch/10970/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/cavium-octeon/executive/cvmx-helper-xaui.c

@@ -151,7 +151,12 @@ int __cvmx_helper_xaui_enable(int interface)
 	/* (4)c Aply reset sequence */
 	xauiCtl.u64 = cvmx_read_csr(CVMX_PCSXX_CONTROL1_REG(interface));
 	xauiCtl.s.lo_pwr = 0;
-	xauiCtl.s.reset = 1;
+
+	/* Issuing a reset here seems to hang some CN68XX chips. */
+	if (!OCTEON_IS_MODEL(OCTEON_CN68XX_PASS1_X) &&
+	    !OCTEON_IS_MODEL(OCTEON_CN68XX_PASS2_X))
+		xauiCtl.s.reset = 1;
+
 	cvmx_write_csr(CVMX_PCSXX_CONTROL1_REG(interface), xauiCtl.u64);
 
 	/* Wait for PCS to come out of reset */