[PATCH v2 2/2] serial: rsci: Remove goto and refactor baud rate clock selection

[Biju]

From: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>

Replace the goto done pattern in rsci_set_termios() with a positive
conditional block. When baud rate is zero, the clock selection logic
is now simply skipped rather than jumping to a 'done' label, eliminating
the goto entirely.

Since RSCI only uses a single clock source (SCI_FCK), the multi-clock
tracking variables (best_clk, min_err, brr1, srr1, cks1) are redundant
and removed. ccr0_val and ccr4_val are likewise dropped, replaced with
hardcoded 0 at their write sites, as they were never modified from their
initial zero values.

No functional change intended.

Reported-by: Pavel Machek <pavel@xxxxxxxxxxxx>
Closes: https://lore.kernel.org/all/abPpZULsXhRmXTX9@xxxxxxxxxx/
Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
---
v1->v2:
 * Dropped the check (abs(err) < abs(min_err) as it is always true.
 * Dropped the check (abs(err) < abs(min_err) as it is always true.
 * Dropped variables best_clk and min_err as they are no longer needed.
 * Dropped intermediate variables brr1, cks1 and srr1; results are now
   written directly into brr, cks and srr.
 * Moved dev_dbg() inside the if (baud) block.
 * Dropped ccr0_val and ccr4_val, replaced with hardcoded 0 at their
   write sites, as they were never modified from their initial values.
 * Scoped variables err and srr locally within the if (baud) block.
 * Updated commit description.
---
 drivers/tty/serial/rsci.c | 33 +++++++++++----------------------
 1 file changed, 11 insertions(+), 22 deletions(-)

diff --git a/drivers/tty/serial/rsci.c b/drivers/tty/serial/rsci.c
index a0858bab0822..c2440fd5c02d 100644
--- a/drivers/tty/serial/rsci.c
+++ b/drivers/tty/serial/rsci.c
@@ -217,16 +217,13 @@ static void rsci_set_termios(struct uart_port *port, struct ktermios *termios,
 			     const struct ktermios *old)
 {
 	unsigned int ccr2_val = CCR2_INIT, ccr3_val = CCR3_INIT;
-	unsigned int ccr0_val = 0, ccr1_val = 0, ccr4_val = 0;
-	unsigned int brr1 = 255, cks1 = 0, srr1 = 15;
 	struct sci_port *s = to_sci_port(port);
 	unsigned int brr = 255, cks = 0;
-	int min_err = INT_MAX, err;
-	unsigned long max_freq = 0;
+	unsigned int ccr1_val = 0;
+	unsigned long max_freq;
 	unsigned int baud, i;
 	unsigned long flags;
 	unsigned int ctrl;
-	int best_clk = -1;
 
 	if ((termios->c_cflag & CSIZE) == CS7) {
 		ccr3_val |= CCR3_CHR0;
@@ -265,23 +262,15 @@ static void rsci_set_termios(struct uart_port *port, struct ktermios *termios,
 	}
 
 	baud = uart_get_baud_rate(port, termios, old, 0, max_freq);
-	if (!baud)
-		goto done;
-
-	/* Divided Functional Clock using standard Bit Rate Register */
-	err = sci_scbrr_calc(s, baud, &brr1, &srr1, &cks1);
-	if (abs(err) < abs(min_err)) {
-		best_clk = SCI_FCK;
-		ccr0_val = 0;
-		min_err = err;
-		brr = brr1;
-		cks = cks1;
-	}
+	if (baud) {
+		unsigned int srr;
+		int err;
 
-done:
-	if (best_clk >= 0)
+		/* Divided Functional Clock using standard Bit Rate Register */
+		err = sci_scbrr_calc(s, baud, &brr, &srr, &cks);
 		dev_dbg(port->dev, "Using clk %pC for %u%+d bps\n",
-			s->clks[best_clk], baud, min_err);
+			s->clks[SCI_FCK], baud, err);
+	}
 
 	sci_port_enable(s);
 	uart_port_lock_irqsave(port, &flags);
@@ -289,7 +278,7 @@ static void rsci_set_termios(struct uart_port *port, struct ktermios *termios,
 	if (baud)
 		uart_update_timeout(port, termios->c_cflag, baud);
 
-	rsci_serial_out(port, CCR0, ccr0_val);
+	rsci_serial_out(port, CCR0, 0);
 
 	ccr3_val |= CCR3_FM;
 	rsci_serial_out(port, CCR3, ccr3_val);
@@ -298,7 +287,7 @@ static void rsci_set_termios(struct uart_port *port, struct ktermios *termios,
 	rsci_serial_out(port, CCR2, ccr2_val);
 
 	rsci_serial_out(port, CCR1, ccr1_val);
-	rsci_serial_out(port, CCR4, ccr4_val);
+	rsci_serial_out(port, CCR4, 0);
 
 	ctrl = rsci_serial_in(port, FCR);
 	ctrl |= (FCR_RFRST | FCR_TFRST);
-- 
2.43.0