From 2334de198fed3da72e9785ecdd691d101aa96e77 Mon Sep 17 00:00:00 2001 From: Alexander Shiyan Date: Wed, 17 Feb 2021 11:06:08 +0300 Subject: [PATCH] Revert "serial: max310x: rework RX interrupt handling" This reverts commit fce3c5c1a2d9cd888f2987662ce17c0c651916b2. FIFO is triggered 4 intervals after receiving a byte, it's good when we don't care about the time of reception, but are only interested in the presence of any activity on the line. Unfortunately, this method is not suitable for all tasks, for example, the RS-485 protocol will not work properly, since the state machine must track the request-response time and after the timeout expires, a decision is made that the device on the line is not responding. Signed-off-by: Alexander Shiyan Link: https://lore.kernel.org/r/20210217080608.31192-1-shc_work@mail.ru Fixes: fce3c5c1a2d9 ("serial: max310x: rework RX interrupt handling") Cc: Thomas Petazzoni Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/max310x.c | 29 +++++------------------------ 1 file changed, 5 insertions(+), 24 deletions(-) diff --git a/drivers/tty/serial/max310x.c b/drivers/tty/serial/max310x.c index 9795b2e..1b61d26 100644 --- a/drivers/tty/serial/max310x.c +++ b/drivers/tty/serial/max310x.c @@ -1056,9 +1056,9 @@ static int max310x_startup(struct uart_port *port) max310x_port_update(port, MAX310X_MODE1_REG, MAX310X_MODE1_TRNSCVCTRL_BIT, 0); - /* Reset FIFOs */ - max310x_port_write(port, MAX310X_MODE2_REG, - MAX310X_MODE2_FIFORST_BIT); + /* Configure MODE2 register & Reset FIFOs*/ + val = MAX310X_MODE2_RXEMPTINV_BIT | MAX310X_MODE2_FIFORST_BIT; + max310x_port_write(port, MAX310X_MODE2_REG, val); max310x_port_update(port, MAX310X_MODE2_REG, MAX310X_MODE2_FIFORST_BIT, 0); @@ -1086,27 +1086,8 @@ static int max310x_startup(struct uart_port *port) /* Clear IRQ status register */ max310x_port_read(port, MAX310X_IRQSTS_REG); - /* - * Let's ask for an interrupt after a timeout equivalent to - * the receiving time of 4 characters after the last character - * has been received. - */ - max310x_port_write(port, MAX310X_RXTO_REG, 4); - - /* - * Make sure we also get RX interrupts when the RX FIFO is - * filling up quickly, so get an interrupt when half of the RX - * FIFO has been filled in. - */ - max310x_port_write(port, MAX310X_FIFOTRIGLVL_REG, - MAX310X_FIFOTRIGLVL_RX(MAX310X_FIFO_SIZE / 2)); - - /* Enable RX timeout interrupt in LSR */ - max310x_port_write(port, MAX310X_LSR_IRQEN_REG, - MAX310X_LSR_RXTO_BIT); - - /* Enable LSR, RX FIFO trigger, CTS change interrupts */ - val = MAX310X_IRQ_LSR_BIT | MAX310X_IRQ_RXFIFO_BIT | MAX310X_IRQ_TXEMPTY_BIT; + /* Enable RX, TX, CTS change interrupts */ + val = MAX310X_IRQ_RXEMPTY_BIT | MAX310X_IRQ_TXEMPTY_BIT; max310x_port_write(port, MAX310X_IRQEN_REG, val | MAX310X_IRQ_CTS_BIT); return 0; -- 2.7.4