clk: agilex/stratix10/n5x: fix how the bypass_reg is handled

If the bypass_reg is set, then we can return the bypass parent, however,
if there is not a bypass_reg, we need to figure what the correct parent
mux is.

The previous code never handled the parent mux if there was a
bypass_reg.

Fixes: 80c6b7a ("clk: socfpga: agilex: add clock driver for the Agilex platform")
Cc: stable@vger.kernel.org
Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>
Link: https://lore.kernel.org/r/20210611025201.118799-4-dinguyen@kernel.org
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

Author: Dinh Nguyen

drivers/clk/socfpga/clk-periph-s10.c

@@ -64,16 +64,21 @@ static u8 clk_periclk_get_parent(struct clk_hw *hwclk)
 {
 	struct socfpga_periph_clk *socfpgaclk = to_periph_clk(hwclk);
 	u32 clk_src, mask;
-	u8 parent;
+	u8 parent = 0;
 
+	/* handle the bypass first */
 	if (socfpgaclk->bypass_reg) {
 		mask = (0x1 << socfpgaclk->bypass_shift);
 		parent = ((readl(socfpgaclk->bypass_reg) & mask) >>
 			   socfpgaclk->bypass_shift);
-	} else {
+		if (parent)
+			return parent;
+	}
+
+	if (socfpgaclk->hw.reg) {
 		clk_src = readl(socfpgaclk->hw.reg);
 		parent = (clk_src >> CLK_MGR_FREE_SHIFT) &
-			CLK_MGR_FREE_MASK;
+			  CLK_MGR_FREE_MASK;
 	}
 	return parent;
 }