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    SubjectRe: [PATCH] i2c-at91: fix data-loss issue
    Apparently the issue with the AT91RM9200 is the chipset itself due to a
    factory design defect. Some people claim that the root cause of it is:

    "Since the TWI doesn't have a DMA channel there is no way to deliver
    timely data to the Tx buffer under heavy CPU load."[1]

    Other threads[2] highlights same issues with the AT91RM9200 and the data
    loss. Even in 2007, Ronny Nilsson tried to do some patch[3] blocking the
    interrupts in order to win more feasibility, some testing was
    performed[4], and up to 100kHz (exactly the same value as we started
    getting errors), the driver just failed. At the end of the discussion
    the conclusion was that the TWI controller of the AT91RM9200 is just
    broken and the GPIO driver is the only alternative.

    Therefore, your driver will work for all of those chipsets using PDC
    with the TWI. However, it won't work with the AT91RM9200 (and probably
    old hardware variants that keep same hardware design).

    So I recommend to add a note/comment indicating such incompatibility for
    the AT91RM9200, either in the source code or in the kernel config.



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