From: Finn Thain <[email protected]> 3.12-stable review patch. If anyone has any objections, please let me know.
=============== commit 56931d73697c99ecf7aba6ae86c94d3a2d15d596 upstream. For SCC initialization we cannot assume that the control register is in the correct state to accept a register pointer. So first read from the control register in order to "sync" up. Signed-off-by: Finn Thain <[email protected]> Signed-off-by: Geert Uytterhoeven <[email protected]> Cc: Oliver Neukum <[email protected]> Signed-off-by: Jiri Slaby <[email protected]> --- arch/m68k/kernel/head.S | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/m68k/kernel/head.S b/arch/m68k/kernel/head.S index ac85f16534af..4180f8b20374 100644 --- a/arch/m68k/kernel/head.S +++ b/arch/m68k/kernel/head.S @@ -2909,7 +2909,9 @@ func_start serial_init,%d0/%d1/%a0/%a1 #if defined(MAC_USE_SCC_A) || defined(MAC_USE_SCC_B) movel %pc@(L(mac_sccbase)),%a0 - /* Reset SCC device */ + /* Reset SCC register pointer */ + moveb %a0@(mac_scc_cha_a_ctrl_offset),%d0 + /* Reset SCC device: write register pointer then register value */ moveb #9,%a0@(mac_scc_cha_a_ctrl_offset) moveb #0xc0,%a0@(mac_scc_cha_a_ctrl_offset) /* Wait for 5 PCLK cycles, which is about 68 CPU cycles */ -- 2.7.0
