• Uwe Kleine-König's avatar
    Serial: pxa: work around Errata #75 · c934878c
    Uwe Kleine-König authored
    Intel(R) PXA27x Processor Family Specification Update (Nov 2005)
    says:
    
      E75. UART: Baud rate may not be programmed correctly on
           back-to-back writes.
    
      Problem:
      When programming the Divisor Latch registers, Low and High (DLL and
      DLH), with back-to-back writes, the second register write may not
      take effect. The result is an incorrect baud rate.
    
      Workaround:
      After programming the first Divisor Latch register, read and verify
      it before programming the second Divisor Latch register.
    
    This was hit when changing the baud rate from 115200 to 9600 while
    receiving characters at 9600 Bd.
    
    And fixed indention of some comments nearby.
    Signed-off-by: default avatarUwe Kleine-König <u.kleine-koenig@pengutronix.de>
    Acked-by: default avatarWolfram Sang <w.sang@pengutronix.de>
    Acked-by: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
    Cc: Eric Miao <eric.y.miao@gmail.com>
    Cc: Alan Cox <alan@linux.intel.com>
    Cc: Mike Rapoport <mike@compulab.co.il>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
    c934878c
pxa.c 20.6 KB