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    SubjectRe: [PATCH] pch_uart: Change default UART clock setting 192MHz
    On 02/21/2012 03:43 PM, Tomoya MORINAGA wrote:
    > 2012年2月22日1:07 Darren Hart <dvhart@linux.intel.com>:
    >> When does the phub driver update the clock registers?
    >
    > I've already posted pch_phub patch for 192MHz setting.
    > You can see the patch form below.

    Yes, I applied the patch. The problem seems to be this:

    DVHART: parse_options (8250_early.c)
    DVHART: pch_console_setup
    DVHART: pch_console_setup
    DVHART: pch_phub_probe: set CLKCFG UART to 192MHz

    As you can see, the pch_phub_probe happens much too late.

    I can get it to work with a boot command line like this:
    earlycon=uart8250,io,0x2050,115200n8 console=ttyPCH1,115200n8

    And hacking all the BASE_BAUD references to be 48000000
    (my current hardware sets the clock to 48MHz in firmware).
    This gets things working until pch_phub gets around to setting
    the CLKCFG register for the UART clock.

    I'd prefer to not have to use the earlycon parameter/code,
    but we need a way for the pch_uart to understand the difference
    between early boot and post-phub setup. Can we read the CLKCFG
    register in pch_console_setup to dynamically configure the
    port->uartclk? (not sure that's even the right place to do it).

    --
    Darren

    >>> Signed-off-by: Tomoya MORINAGA <tomoya.rohm@gmail.com>
    >>> ---
    >>> Related patch is
    >>> http://marc.info/?l=linux-kernel&m=132979974907774&w=2
    >
    > ---
    > ROHM Co., Ltd.
    > tomoya

    --
    Darren Hart
    Intel Open Source Technology Center
    Yocto Project - Linux Kernel


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