Hi Leif,
On 08/10/2015 07:23 PM, Leif Lindholm wrote:
> 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.
Thanks for the bug report and bisect, and apologies for the breakage;
I should have caught that on review.
Would you please test the patch below and see if that resolves the
problem for you?
Regards,
Peter Hurley
PS - _NOT_ even compile-tested, sorry.
--- >% ---
Subject: [PATCH] serial: pl011: Fix earlycon register LUT breakage
Commit 7b753f318d14 ("uart: pl011: Introduce register accessor")
mistakenly used the register LUT i/o accessors for the pl011
earlycon. Since the port has not been probed at earlycon time,
the struct uart_amba_port (and register LUTs) are uninitialized.
Use direct register addressing for pl011 earlycon; other h/w supported
by the amba-pl011 driver should declare an alternate earlycon.
Cc: Jun Nie <jun.nie@xxxxxxxxxx>
Signed-off-by: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/amba-pl011.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)
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)
;
}
--
2.5.0
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