• H
    [PATCH] atmel_serial: Fix roundoff error in atmel_console_get_options · 4d5e392c
    Haavard Skinnemoen 提交于
    The atmel_console_get_options() function initializes the baud,
    parity and bits settings from the actual hardware setup, in
    case it has been initialized by a e.g. boot loader.
    
    The baud rate, however, is not necessarily exactly equal to one of
    the standard baud rates (115200, etc.) This means that the baud rate
    calculated by this function may be slightly higher or slightly lower
    than one of the standard baud rates.
    
    If the baud rate is slightly lower than the target, this causes
    problems when uart_set_option() tries to match the detected baud rate
    against the standard baud rate, as it will always select a baud rate
    that is lower or equal to the target rate. For example if the
    detected baud rate is slightly lower than 115200, usart_set_options()
    will select 57600.
    
    This patch fixes the problem by subtracting 1 from the value in BRGR
    when calculating the baud rate. The detected baud rate will thus
    always be higher than the nearest standard baud rate, and
    uart_set_options() will end up doing the right thing.
    
    Tested on ATSTK1000 and AT91RM9200-EK boards. Both are broken without
    this patch.
    Signed-off-by: NHaavard Skinnemoen <hskinnemoen@atmel.com>
    Acked-by: NAndrew Victor <andrew@sanpeople.com>
    Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
    4d5e392c
atmel_serial.c 24.7 KB