clk: analogbits: Fix incorrect calculation of vco rate delta

[ Upstream commit d7f12857f0 ]

In wrpll_configure_for_rate() we try to determine the best PLL
configuration for a target rate. However, in the loop where we try
values of R, we should compare the derived `vco` with `target_vco_rate`.
However, we were in fact comparing it with `target_rate`, which is
actually after Q shift. This is incorrect, and sometimes can result in
suboptimal clock rates. Fix it.

Fixes: 7b9487a9a5 ("clk: analogbits: add Wide-Range PLL library")
Signed-off-by: Bo Gan <ganboing@gmail.com>
Link: https://lore.kernel.org/r/20240830061639.2316-1-ganboing@gmail.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/clk/analogbits/wrpll-cln28hpc.c

@@ -291,7 +291,7 @@ int wrpll_configure_for_rate(struct wrpll_cfg *c, u32 target_rate,
 			vco = vco_pre * f;
 		}
 
-		delta = abs(target_rate - vco);
+		delta = abs(target_vco_rate - vco);
 		if (delta < best_delta) {
 			best_delta = delta;
 			best_r = r;