Re: earlycon issues in -next with amba-pl011 updates
From: Jun Nie <hidden>
Date: 2015-08-11 01:48:24
Also in:
linux-arm-kernel
2015-08-11 7:23 GMT+08:00 Leif Lindholm [off-list ref]:
Hi all,
The kernelci.org bot picked up a complete boot failure (no output past
UEFI stub) with next-20150806 and Tyler bisected it down to somewhere
in
8cd90e5 uart: pl011: Add support to ZTE ZX296702 uart
09dcc7d uart: pl011: Improve LCRH register access decision
2c096a9 uart: pl011: Introduce register look up table
7b753f3 uart: pl011: Introduce register accessor
The issue only appears with earlycon on command line, for pl011
consoles.
Some investigation shows that the cause lies with
commit 7b753f318d14 ("uart: pl011: Introduce register accessor")
and
commit 2c096a9eedc6 ("uart: pl011: Introduce register look up table")
Specifically, the changes to pl011_putc() are incorrect:
The new pl011_ accessors take a (struct uart_amba_port *) input, but
pl011_putc() directly uses the incoming (struct uart_port *) for this.
Apart from ending up with an unintended/incorrect UART base address,
the introduction of the lookup table for register offsets also means
the accessors try to dereference (struct uart_amba_port *)->reg_lut.
The below is a hack that shows/resolves the issue, but some
refactoring of the original patches might be in order.
/
LeifLeif, Sorry for the inconvenience. I do not have idea of early console till now and I always have debug console for early panic debug. Learned more from this issue. Suppose Peter's patch will resolve your issue. Jun
quoted hunk ↗ jump to hunk
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c index 2af09ab..452dbba 100644 --- a/drivers/tty/serial/amba-pl011.c +++ b/drivers/tty/serial/amba-pl011.c@@ -2348,13 +2348,14 @@ 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); + struct uart_amba_port uap; + uap.port = *port; + uap.reg_lut = arm_reg; - while (pl011_readw(uap, REG_FR) & UART01x_FR_TXFF) + while (pl011_readw(&uap, REG_FR) & UART01x_FR_TXFF) ; - pl011_writeb(uap, c, REG_DR); - while (pl011_readw(uap, REG_FR) & uap->fr_busy) + pl011_writeb(&uap, c, REG_DR); + while (pl011_readw(&uap, REG_FR) & UART01x_FR_BUSY) ; } --2.1.4