Re: earlycon issues in -next with amba-pl011 updates
From: Russell King - ARM Linux <hidden>
Date: 2015-08-11 12:40:43
Also in:
linux-arm-kernel
On Mon, Aug 10, 2015 at 08:31:03PM -0400, Peter Hurley wrote:
quoted hunk ↗ jump to hunk
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c index 2af09ab..fd54991 100644 --- a/drivers/tty/serial/amba-pl011.c +++ b/drivers/tty/serial/amba-pl011.c@@ -2348,13 +2348,10 @@ static struct console amba_console = { static void pl011_putc(struct uart_port *port, int c) { - struct uart_amba_port *uap = - container_of(port, struct uart_amba_port, port); - - while (pl011_readw(uap, REG_FR) & UART01x_FR_TXFF) + while (readl(port->membase + UART01x_FR) & UART01x_FR_TXFF) ; - pl011_writeb(uap, c, REG_DR); - while (pl011_readw(uap, REG_FR) & uap->fr_busy) + writeb(c, port->membase + UART01x_DR); + while (readl(port->membase + UART01x_FR) & UART01x_FR_BUSY) ;
These loops are wrong. Kernel coding style is that loops like this
will use cpu_relax() in them, just like the driver used to. This
was introduced by:
commit 0d3c673e7881e691991b2a4745bd4f149603baa2
Author: Rob Herring [off-list ref]
Date: Fri Apr 18 17:19:57 2014 -0500
tty/serial: pl011: add generic earlycon support
Also, the above readl()s should be readl_relaxed(), we don't need
barriered reads or to hit the L2 cache on those reads in the above code.
--
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