From: "Ji-Ze Hong (Peter Hong)" <hpeter@gmail.com>
To: johan@kernel.org
Cc: gregkh@linuxfoundation.org, linux-usb@vger.kernel.org,
linux-kernel@vger.kernel.org, peter_hong@fintek.com.tw,
"Ji-Ze Hong (Peter Hong)" <hpeter+linux_kernel@gmail.com>
Subject: [PATCH V3 6/6] usb: serial: f81534: fix tx error on some baud rate
Date: Thu, 11 Jan 2018 14:47:20 +0800 [thread overview]
Message-ID: <1515653240-5420-6-git-send-email-hpeter+linux_kernel@gmail.com> (raw)
In-Reply-To: <1515653240-5420-1-git-send-email-hpeter+linux_kernel@gmail.com>
The F81532/534 had 4 clocksource 1.846/18.46/14.77/24MHz and baud rates
can be up to 1.5Mbits with 24MHz. But on some baud rate (384~500kps), the
TX side will send the data frame too close to treat frame error on RX
side. This patch will force all TX data frame with delay 1bit gap.
Signed-off-by: Ji-Ze Hong (Peter Hong) <hpeter+linux_kernel@gmail.com>
---
V3:
1: had not noticeable changes.
V2:
1: First introduced in this series patches.
drivers/usb/serial/f81534.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/serial/f81534.c b/drivers/usb/serial/f81534.c
index 08ef72ea2eec..92c9d8f18a5a 100644
--- a/drivers/usb/serial/f81534.c
+++ b/drivers/usb/serial/f81534.c
@@ -131,6 +131,8 @@
#define F81534_CLK_24_MHZ BIT(2)
#define F81534_CLK_14_77_MHZ GENMASK(2, 1)
#define F81534_CLK_MASK GENMASK(2, 1)
+#define F81534_CLK_TX_DELAY_1BIT BIT(3)
+
#define F81534_CLK_RS485_MODE BIT(4)
#define F81534_CLK_RS485_INVERT BIT(5)
@@ -1386,7 +1388,11 @@ static int f81534_port_probe(struct usb_serial_port *port)
if (!port_priv)
return -ENOMEM;
- port_priv->shadow_clk = F81534_UART_EN;
+ /*
+ * We'll make tx frame error when baud rate from 384~500kps. So we'll
+ * delay all tx data frame with 1bit.
+ */
+ port_priv->shadow_clk = F81534_UART_EN | F81534_CLK_TX_DELAY_1BIT;
spin_lock_init(&port_priv->msr_lock);
mutex_init(&port_priv->mcr_mutex);
mutex_init(&port_priv->lcr_mutex);
--
2.7.4
prev parent reply other threads:[~2018-01-11 6:47 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-11 6:47 [PATCH V3 1/6] usb: serial: f81534: add high baud rate support Ji-Ze Hong (Peter Hong)
2018-01-11 6:47 ` [PATCH V3 2/6] usb: serial: f81534: add auto RTS direction support Ji-Ze Hong (Peter Hong)
2018-01-11 10:05 ` Johan Hovold
2018-01-11 6:47 ` [PATCH V3 3/6] usb: serial: f81534: add output pin control Ji-Ze Hong (Peter Hong)
2018-01-11 6:47 ` [PATCH V3 4/6] usb: serial: f81534: refactoring calc_num_ports() Ji-Ze Hong (Peter Hong)
2018-01-11 6:47 ` [PATCH V3 5/6] usb: serial: f81534: add H/W disable port support Ji-Ze Hong (Peter Hong)
2018-01-11 6:47 ` Ji-Ze Hong (Peter Hong) [this message]
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