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    SubjectRe: [PATCH] serial: 8250_dw: Fix LCR workaround regression
    Hi,

    On Tue, Dec 10, 2013 at 10:28:04PM +0000, James Hogan wrote:
    > From: James Hogan <james.hogan@imgtec.com>
    >
    > Commit c49436b657d0 (serial: 8250_dw: Improve unwritable LCR workaround)
    > caused a regression. It added a check that the LCR was written properly
    > to detect and workaround the busy quirk, but the behaviour of bit 5
    > (UART_LCR_SPAR) differs between IP versions 3.00a and 3.14c per the
    > docs. On older versions this caused the check to fail and it would
    > repeatedly force idle and rewrite the LCR register, causing delays and
    > preventing any input from serial being received.
    >
    > This is fixed by masking out UART_LCR_SPAR before making the comparison.
    >
    > Signed-off-by: James Hogan <james.hogan@imgtec.com>
    > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    > Cc: Jiri Slaby <jslaby@suse.cz>
    > Cc: Tim Kryger <tim.kryger@linaro.org>
    > Cc: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
    > Cc: Matt Porter <matt.porter@linaro.org>
    > Cc: Markus Mayer <markus.mayer@linaro.org>
    > Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
    > Tested-by: Tim Kryger <tim.kryger@linaro.org>
    > Tested-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>

    I tested this with HW without the busy functionality
    (UART_16550_COMPATIBLE == yes). No problems here. FWIW:

    Tested-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>


    --
    heikki


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