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    SubjectRe: [PATCH v2] input: mouse: add qci touchpad driver
    On 8/12/2010 10:49 PM, Dmitry Torokhov wrote:
    > On Thu, Aug 12, 2010 at 01:58:18PM -0400, Neil Leeder wrote:
    > Actually, since this is not a new touchpad but simply a PS/2 interface
    > it should be implemented as a serio driver, not input device driver.
    >
    Dmitri,

    Thanks for supplying that serio driver. I just have a couple of questions.

    Even though the interface on the wpce775x EC happens to be a PS/2
    interface, this is completely hidden by the firmware on that device. To
    the linux driver it looks like a dedicated i2c connection directly to
    the touchpad. You can't substitute any other device on that PS/2
    interface without rewriting the firmware in the EC - it's not a generic
    interface. A manufacturer could even move the touchpad from the PS/2
    interface to say GPIOs, re-write the firmware and the linux driver
    couldn't tell the difference. Does that change the rationale for using a
    serio driver?

    If the request to use a serio driver is still valid, then it seems that
    the workqueue from the interrupt handler sends each byte of data
    received over i2c in a separate serio_interrupt() call to the touchpad
    driver. Touchpad data comes in 3-byte packets, so the touchpad driver
    will have to re-assemble the packet from 3 separate interrupts. Is that
    the intended use?

    > Could you please tell me if the following works for you? Note that it
    > expects IRQ to be set up properly (edge vs. level trigger) by the
    > platform code

    The i2c_board_info that supplies the irq # from platform code doesn't
    have a way to set i2c flags, and can't set_irq_type() until after
    irq_request(). This may require another platform_data struct to pass the
    trigger level in.

    Thanks.

    --
    Neil
    --
    Sent by an employee of the Qualcomm Innovation Center, Inc.
    The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.


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