Why can't I drive the inclk of an ALTPLL with the tx_clkout of an ALTGX transceiver in Cyclone IV GX devices?

Due to a bug in the Quartus® II Software Version 10.1 you cannot feed the inclk port of an ALTPLL Megafunction® with a tx_clkout of an ALTGX transceiver Megafunction in Cyclone® IV GX devices.

Implementing this topology will result in an error similar to the following.

Error: Port CLKOUT of GXB Transmitter Channel Atom b1:inst1|b1_alt_c3gxb:b1_alt_c3gxb_component|transmit_pcs0 cannot be connected to PLL Atom a1:inst|altpll:altpll_component|a1_altpll:auto_generated|pll1

To fix this problem, you can install the following patch.

• Quartus II 10.1 Patch 0.03 readme file
• Quartus II 10.1 Patch 0.03 for Linux
• Quartus II 10.1 Patch 0.03 for Windows

This is fixed in the Quartus II Software version 10.1SP1.