NS16550A: Restore HS settings in EXCR2 on resume (b5b82df6) · Commits · 戴 / test

After a suspend/resume cycle, the UART may have been reset into low-speed mode -- either because it's actually been reset, or because the firmware pokes at the old-style divisor registers. If we detected it as a NS16550A SuperIO chip in the first place and set baud_base to 921600, then we should do so again in the resume path. This patch adds that code to serial8250_resume_port(), and also makes serial8250_resume() actually call serial8250_resume_port() for each port instead of just calling uart_resume_port() directly. And thus fixes serial port operation after suspend/resume. It also fixes a bogus comment where we write the EXCR2 register with a comment saying /* EXCR1 */ Signed-off-by:

David Woodhouse <dwmw2@infradead.org> Acked-by:

Alan Cox <alan@redhat.com> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

drivers/serial/8250.c

+18 −3

Original line number	Diff line number	Diff line
		@@ -894,7 +894,7 @@ static void autoconfig_16550a(struct uart_8250_port *up)
		quot = serial_dl_read(up);
		quot <<= 3;

		status1 = serial_in(up, 0x04); /* EXCR1 */
		status1 = serial_in(up, 0x04); /* EXCR2 */
		status1 &= ~0xB0; /* Disable LOCK, mask out PRESL[01] */
		status1 \|= 0x10; /* 1.625 divisor for baud_base --> 921600 */
		serial_outp(up, 0x04, status1);
		@@ -2617,7 +2617,22 @@ void serial8250_suspend_port(int line)
		*/
		void serial8250_resume_port(int line)
		{
		uart_resume_port(&serial8250_reg, &serial8250_ports[line].port);
		struct uart_8250_port *up = &serial8250_ports[line];

		if (up->capabilities & UART_NATSEMI) {
		unsigned char tmp;

		/* Ensure it's still in high speed mode */
		serial_outp(up, UART_LCR, 0xE0);

		tmp = serial_in(up, 0x04); /* EXCR2 */
		tmp &= ~0xB0; /* Disable LOCK, mask out PRESL[01] */
		tmp \|= 0x10; /* 1.625 divisor for baud_base --> 921600 */
		serial_outp(up, 0x04, tmp);

		serial_outp(up, UART_LCR, 0);
		}
		uart_resume_port(&serial8250_reg, &up->port);
		}

		/*
		@@ -2694,7 +2709,7 @@ static int serial8250_resume(struct platform_device *dev)
		struct uart_8250_port *up = &serial8250_ports[i];

		if (up->port.type != PORT_UNKNOWN && up->port.dev == &dev->dev)
		uart_resume_port(&serial8250_reg, &up->port);
		serial8250_resume_port(i);
		}

		return 0;

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