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_ker...@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
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