[PATCH v2] serial: pl011: Fix earlycon register LUT breakage

[Jun Nie]

2015-09-08 15:52 GMT+08:00 Jun Nie <jun.nie at linaro.org>:
> 2015-09-08 10:23 GMT+08:00 Jun Nie <jun.nie at linaro.org>:
>> 2015-09-05 23:57 GMT+08:00 Jun Nie <jun.nie at linaro.org>:
>>> 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.
>>>
>>> Signed-off-by: Peter Hurley <peter at hurleysoftware.com>
>>> Signed-off-by: Jun Nie <jun.nie at linaro.org>
>>> ---
>>>  drivers/tty/serial/amba-pl011.c | 15 +++------------
>>>  1 file changed, 3 insertions(+), 12 deletions(-)
>>>
>>> diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
>>> index 2af09ab..cce41e0 100644
>>> --- a/drivers/tty/serial/amba-pl011.c
>>> +++ b/drivers/tty/serial/amba-pl011.c
>>> @@ -326,12 +326,6 @@ static void pl011_writew(struct uart_amba_port *uap, int val, int index)
>>>         writew_relaxed(val, uap->port.membase + uap->reg_lut[index]);
>>>  }
>>>
>>> -static void pl011_writeb(struct uart_amba_port *uap, u8 val, int index)
>>> -{
>>> -       WARN_ON(index > REG_NR);
>>> -       writeb_relaxed(val, uap->port.membase + uap->reg_lut[index]);
>>> -}
>>> -
>>>  /*
>>>   * Reads up to 256 characters from the FIFO or until it's empty and
>>>   * inserts them into the TTY layer. Returns the number of characters
>>> @@ -2348,13 +2342,10 @@ 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 (readw_relaxed(port->membase + UART01x_FR) & UART01x_FR_TXFF)
>>>                 ;
>>> -       pl011_writeb(uap, c, REG_DR);
>>> -       while (pl011_readw(uap, REG_FR) & uap->fr_busy)
>>> +       writeb_relaxed(c, port->membase + UART01x_DR);
>>> +       while (readw_relaxed(port->membase + UART01x_FR) & UART01x_FR_BUSY)
>>>                 ;
>>>  }
>>>
>>> --
>>> 1.9.1
>>>
>>
>> Could anybody help test this earlycon patch on hardware with standard
>> pl011 serial? Your help is appreciated and valuable no matter the
>> previous patch set is carried on or reverted.
>> Thank you very much!
>>
>> Jun

cc linux-arm-kernel at lists.infradead.org in case someone may have
resource to help have a test. Thank you!

Jun