From 47b1747f705e90d8197b77207e19c0ec67c16958 Mon Sep 17 00:00:00 2001 From: Robert Middleton Date: Thu, 1 Aug 2019 10:56:40 -0400 Subject: [PATCH] serial: 8250_exar: Clear buffer before shutdown When closing and shutting down the exar serial port, if the chip has not finished sending all of the data in its buffer, the remaining bytes will be lost. Hold off on the shutdown until the bytes have all been sent. Signed-off-by: Robert Middleton Link: https://lore.kernel.org/r/20190801145640.26080-1-robert.middleton@rm5248.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/8250/8250_exar.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/drivers/tty/serial/8250/8250_exar.c b/drivers/tty/serial/8250/8250_exar.c index 3a39368e6e47..357e20a6566f 100644 --- a/drivers/tty/serial/8250/8250_exar.c +++ b/drivers/tty/serial/8250/8250_exar.c @@ -19,6 +19,7 @@ #include #include #include +#include #include @@ -515,6 +516,27 @@ static irqreturn_t exar_misc_handler(int irq, void *data) return IRQ_HANDLED; } +static void +exar_shutdown(struct uart_port *port) +{ + unsigned char lsr; + bool tx_complete = 0; + struct uart_8250_port *up = up_to_u8250p(port); + struct circ_buf *xmit = &port->state->xmit; + int i = 0; + + do { + lsr = serial_in(up, UART_LSR); + if (lsr & (UART_LSR_TEMT | UART_LSR_THRE)) + tx_complete = 1; + else + tx_complete = 0; + msleep(1); + } while (!uart_circ_empty(xmit) && !tx_complete && i++ < 1000); + + serial8250_do_shutdown(port); +} + static int exar_pci_probe(struct pci_dev *pcidev, const struct pci_device_id *ent) { @@ -555,6 +577,7 @@ exar_pci_probe(struct pci_dev *pcidev, const struct pci_device_id *ent) uart.port.flags = UPF_SHARE_IRQ | UPF_EXAR_EFR | UPF_FIXED_TYPE | UPF_FIXED_PORT; uart.port.irq = pci_irq_vector(pcidev, 0); uart.port.dev = &pcidev->dev; + uart.port.shutdown = exar_shutdown; rc = devm_request_irq(&pcidev->dev, uart.port.irq, exar_misc_handler, IRQF_SHARED, "exar_uart", priv);