[lkml]   [2010]   [Jan]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: [PATCH v2] input: MXC: add mxc-keypad driver to support the Keypad Port present in the mxc application processors family.
    Hi Alberto,

    On Sat, Jan 16, 2010 at 06:48:45PM +0100, Alberto Panizzo wrote:
    > Version 2 for this driver proposal.
    > --------------------------------------------------------------------------------
    > The MXC family of Application Processors is shipped with a Keypad Port
    > supported now by this driver.
    > The peripheral can control up to an 8x8 matrix key pad where all the scanning
    > procedure is done via software.
    > The hardware provide two interrupts: one for a key pressed (KDI) and one for
    > all key releases (KRI). There is also a simple circuit for glitch reduction
    > (said for synchronization) made by two series of 3 D-latches clocked by the
    > keypad-clock that stabilize the interrupts sources.
    > KDI and KRI are fired only if the respective conditions are maintained for at
    > last 4 keypad-clock cycle.
    > Those simple synchronization circuits are used also for multiple key pressures:
    > between a KDI and a KRI the driver reset the sync circuit and re-enable the KDI
    > interrupt so after 3 keypad-clock cycle another KDI is fired making possible to
    > repeat the matrix scan operation.

    Nicely looking driver, thank you.

    > This algorithm is done via a threaded management of the keypad interrupt source
    > and delayed by a proper (and longer) debounce interval controlled by the
    > platform initialization.

    This I am not so sure about - the core of the matrix scan routine does
    not sleep so I wonder if starting a separate thread is not too wasteful
    in this case - you can easily do whan you want with a timer, no?

    > +
    > + /*
    > + * Search for rows and cols enabled
    > + */
    > + keymap_data = (struct matrix_keymap_data *) pdata->keymap_data;

    Why do you need to cast away constness instead of declaring keymap_data
    as const pointer?


     \ /
      Last update: 2010-01-26 10:55    [W:0.022 / U:3.328 seconds]
    ©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site