forked from Minki/linux
Revert "serial: uart: add hw flow control support configuration"
This reverts commit 06aa82e498
.
This commit purports to enable auto CTS flow control for the 8250
UART driver. However, the 8250 UART driver already supports auto
CTS flow control via UART_CAP_AFE and UART_CAP_EFR. Indeed, this
patch introduces another DT attribute for which an existing firmware
flag already exists ("auto-flow-control"). Furthermore, the use of
UPF_HARD_FLOW requires the UART driver to define .throttle and
.unthrottle methods, neither of which are defined for the 8250 UART
driver (which will result in a NULL ptr dereference). Finally, this patch
supposes to fix existing bugs in the serial core for auto CTS-enabled
hardware, but does not include the class of hardware for which these
bugs exist.
CC: Murali Karicheri <m-karicheri2@ti.com>
CC: Rob Herring <robh+dt@kernel.org>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
parent
95562e7fdf
commit
a6eec92ec0
@ -37,7 +37,6 @@ Optional properties:
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- auto-flow-control: one way to enable automatic flow control support. The
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driver is allowed to detect support for the capability even without this
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property.
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- has-hw-flow-control: the hardware has flow control capability.
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Example:
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@ -2319,11 +2319,9 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
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* the trigger, or the MCR RTS bit is cleared. In the case where
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* the remote UART is not using CTS auto flow control, we must
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* have sufficient FIFO entries for the latency of the remote
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* UART to respond. IOW, at least 32 bytes of FIFO. Also enable
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* AFE if hw flow control is supported
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* UART to respond. IOW, at least 32 bytes of FIFO.
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*/
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if ((up->capabilities & UART_CAP_AFE && (port->fifosize >= 32)) ||
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(port->flags & UPF_HARD_FLOW)) {
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if (up->capabilities & UART_CAP_AFE && port->fifosize >= 32) {
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up->mcr &= ~UART_MCR_AFE;
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if (termios->c_cflag & CRTSCTS)
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up->mcr |= UART_MCR_AFE;
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@ -183,10 +183,6 @@ static int of_platform_serial_probe(struct platform_device *ofdev)
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"auto-flow-control"))
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port8250.capabilities |= UART_CAP_AFE;
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if (of_property_read_bool(ofdev->dev.of_node,
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"has-hw-flow-control"))
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port8250.port.flags |= UPF_HARD_FLOW;
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ret = serial8250_register_8250_port(&port8250);
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break;
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}
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@ -175,12 +175,8 @@ static int uart_port_startup(struct tty_struct *tty, struct uart_state *state,
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if (tty->termios.c_cflag & CBAUD)
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uart_set_mctrl(uport, TIOCM_RTS | TIOCM_DTR);
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}
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/*
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* if hw support flow control without software intervention,
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* then skip the below check
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*/
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if (tty_port_cts_enabled(port) &&
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!(uport->flags & UPF_HARD_FLOW)) {
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if (tty_port_cts_enabled(port)) {
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spin_lock_irq(&uport->lock);
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if (!(uport->ops->get_mctrl(uport) & TIOCM_CTS))
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tty->hw_stopped = 1;
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@ -2789,9 +2785,7 @@ void uart_handle_cts_change(struct uart_port *uport, unsigned int status)
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uport->icount.cts++;
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/* skip below code if the hw flow control is supported */
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if (tty_port_cts_enabled(port) &&
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!(uport->flags & UPF_HARD_FLOW)) {
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if (tty_port_cts_enabled(port)) {
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if (tty->hw_stopped) {
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if (status) {
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tty->hw_stopped = 0;
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