serial: mvebu-uart: initialize over sampling stack register (35d7a58a) · Commits · 戴 / test

The baudrate derivation relies on the state of the programmable over sampling stack (OSAMP register) being empty, while never initializing it. Set all the fields of this register to 0 (except reserved areas) to ensure a x16 divisor, as assumed by the driver. The suspend/resume callbacks are untouched because they already save/restore correctly this register. Suggested-by:

Thomas Petazzoni <thomas.petazzoni@bootlin.com> Signed-off-by:

Miquel Raynal <miquel.raynal@bootlin.com> Signed-off-by:

Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/mvebu-uart.c

+6 −1

Original line number	Diff line number	Diff line
		@@ -73,6 +73,7 @@

		#define UART_OSAMP 0x14
		#define OSAMP_DEFAULT_DIVISOR 16
		#define OSAMP_DIVISORS_MASK 0x3F3F3F3F

		#define MVEBU_NR_UARTS 2

		@@ -446,7 +447,7 @@ static int mvebu_uart_baud_rate_set(struct uart_port *port, unsigned int baud)
		{
		struct mvebu_uart *mvuart = to_mvuart(port);
		unsigned int d_divisor, m_divisor;
		u32 brdv;
		u32 brdv, osamp;

		if (IS_ERR(mvuart->clk))
		return -PTR_ERR(mvuart->clk);
		@@ -469,6 +470,10 @@ static int mvebu_uart_baud_rate_set(struct uart_port *port, unsigned int baud)
		brdv \|= d_divisor;
		writel(brdv, port->membase + UART_BRDV);

		osamp = readl(port->membase + UART_OSAMP);
		osamp &= ~OSAMP_DIVISORS_MASK;
		writel(osamp, port->membase + UART_OSAMP);

		return 0;
		}

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