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* [PATCH] tty: serial: samsung: Correct clock selection logic
@ 2020-05-09  1:34 ` Jonathan Bakker
  0 siblings, 0 replies; 6+ messages in thread
From: Jonathan Bakker @ 2020-05-09  1:34 UTC (permalink / raw)
  To: kgene, krzk, gregkh, jslaby, linux-arm-kernel, linux-samsung-soc,
	linux-serial, linux-kernel
  Cc: Jonathan Bakker

Some variants of the samsung tty driver can pick which clock
to use for their baud rate generation.  In the DT conversion,
a default clock was selected to be used if a specific one wasn't
assigned and then a comparison of which clock rate worked better
was done.  Unfortunately, the comparison was implemented in such
a way that only the default clock was ever actually compared.
Fix this by iterating through all possible clocks, except when a
specific clock has already been picked via clk_sel (which is
only possible via board files).

Signed-off-by: Jonathan Bakker <xc-racer2@live.ca>
---
 drivers/tty/serial/samsung_tty.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c
index 73f951d65b93..9d2b4be44209 100644
--- a/drivers/tty/serial/samsung_tty.c
+++ b/drivers/tty/serial/samsung_tty.c
@@ -1281,14 +1281,14 @@ static unsigned int s3c24xx_serial_getclk(struct s3c24xx_uart_port *ourport,
 	struct s3c24xx_uart_info *info = ourport->info;
 	struct clk *clk;
 	unsigned long rate;
-	unsigned int cnt, baud, quot, clk_sel, best_quot = 0;
+	unsigned int cnt, baud, quot, best_quot = 0;
 	char clkname[MAX_CLK_NAME_LENGTH];
 	int calc_deviation, deviation = (1 << 30) - 1;
 
-	clk_sel = (ourport->cfg->clk_sel) ? ourport->cfg->clk_sel :
-			ourport->info->def_clk_sel;
 	for (cnt = 0; cnt < info->num_clks; cnt++) {
-		if (!(clk_sel & (1 << cnt)))
+		/* Keep selected clock if provided */
+		if (ourport->cfg->clk_sel &&
+			!(ourport->cfg->clk_sel & (1 << cnt)))
 			continue;
 
 		sprintf(clkname, "clk_uart_baud%d", cnt);
-- 
2.20.1


^ permalink raw reply related	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2020-05-11 19:54 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-05-09  1:34 [PATCH] tty: serial: samsung: Correct clock selection logic Jonathan Bakker
2020-05-09  1:34 ` Jonathan Bakker
2020-05-11 10:08 ` Krzysztof Kozlowski
2020-05-11 10:08   ` Krzysztof Kozlowski
2020-05-11 19:40   ` Jonathan Bakker
2020-05-11 19:40     ` Jonathan Bakker

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