All of lore.kernel.org
 help / color / mirror / Atom feed
From: Jonathan Bakker <xc-racer2@live.ca>
To: kgene@kernel.org, krzk@kernel.org, gregkh@linuxfoundation.org,
	jslaby@suse.com, linux-arm-kernel@lists.infradead.org,
	linux-samsung-soc@vger.kernel.org, linux-serial@vger.kernel.org,
	linux-kernel@vger.kernel.org
Cc: Jonathan Bakker <xc-racer2@live.ca>
Subject: [PATCH] tty: serial: samsung: Correct clock selection logic
Date: Fri,  8 May 2020 18:34:33 -0700	[thread overview]
Message-ID: <BN6PR04MB06604E63833EA41837EBF77BA3A30@BN6PR04MB0660.namprd04.prod.outlook.com> (raw)

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


WARNING: multiple messages have this Message-ID (diff)
From: Jonathan Bakker <xc-racer2@live.ca>
To: kgene@kernel.org, krzk@kernel.org, gregkh@linuxfoundation.org,
	jslaby@suse.com, linux-arm-kernel@lists.infradead.org,
	linux-samsung-soc@vger.kernel.org, linux-serial@vger.kernel.org,
	linux-kernel@vger.kernel.org
Cc: Jonathan Bakker <xc-racer2@live.ca>
Subject: [PATCH] tty: serial: samsung: Correct clock selection logic
Date: Fri,  8 May 2020 18:34:33 -0700	[thread overview]
Message-ID: <BN6PR04MB06604E63833EA41837EBF77BA3A30@BN6PR04MB0660.namprd04.prod.outlook.com> (raw)

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


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

             reply	other threads:[~2020-05-09  1:34 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-09  1:34 Jonathan Bakker [this message]
2020-05-09  1:34 ` [PATCH] tty: serial: samsung: Correct clock selection logic 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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=BN6PR04MB06604E63833EA41837EBF77BA3A30@BN6PR04MB0660.namprd04.prod.outlook.com \
    --to=xc-racer2@live.ca \
    --cc=gregkh@linuxfoundation.org \
    --cc=jslaby@suse.com \
    --cc=kgene@kernel.org \
    --cc=krzk@kernel.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-samsung-soc@vger.kernel.org \
    --cc=linux-serial@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.