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    SubjectRe: [PATCH 0/5] Input: serio_raw - add monitor/replay debugging interface
    Hi Dmitry,

    I am sorry for getting back to you so late. See below.

    On Sat, Apr 21, 2012 at 2:21 PM, Dmitry Torokhov
    <> wrote:
    > On Tue, Feb 14, 2012 at 11:18:38AM +0800, Daniel Kurtz wrote:
    >> On Wed, Feb 8, 2012 at 11:24 AM, Che-Liang Chiou <> wrote:
    >> >
    >> > The serio_raw driver is designed to provide "raw access" to mice, keyboards
    >> > etc; thus, a driver accessing serio_raw may live entirely in userland.
    >> >
    >> > However, serio_raw lacks testability.  It is practically impossible to do
    >> > regression tests on changes to a serio_raw -based userland driver.  On the other
    >> > hand, the kernel's input subsystem has good testability support.  With the help
    >> > of tools like utouch-evemu, we may capture and replay input events for evdev
    >> > drivers in regression tests.
    >> >
    >> > This patchset contains extensions to the serio_raw driver which add debugfs
    >> > entries for monitoring and replaying byte sequence between a userland driver
    >> > and device.  These byte sequences can be used in regression tests of the
    >> > userland driver.  This patchset closes the gap between serio_raw and the input
    >> > subsystem regarding testability.
    >> >
    >> > This patchset is successfully applied on kernel version 3.3-rc2.
    >> >
    >> > Che-Liang Chiou (5):
    >> >  Input: serio_raw - return proper result when serio_raw_read fails
    >> >  Input: serio_raw - extract queue interface
    >> >  Input: serio_raw - factor out common pattern of write
    >> >  Input: serio_raw - add debugfs interface
    >> >  Input: serio_raw - implement debugfs interface
    >> For patches 3-5:
    >> Reviewed-by: Daniel Kurtz <>
    >> For patch 1 (and its implication on queue_read() in patch 2, I'd
    >> prefer to hear feedback from the list.
    > I have already taken the patch 1, but I am unsure why we need kernel
    > support for the monitor and replay. It seems you should only need a
    > userspace program that would sit between the driver being tested and
    > serio_raw misc device and pipe data back and forth, optionally saving
    > it for subsequent replay.

    Sadly some user space drivers hard codes path, like
    "/dev/serio_raw%d", and quite often their source codes are not
    available; so it is effectively impossible to monitor these drivers
    without kernel's help.

    Besides, changing from accessing a char device to communicating
    through IPC requires rewriting the user space driver, no matter it's a
    pair of named pipes or a socket. This may sometimes be quite hard
    depending on the I/O strategy of the driver.

    > Thanks.
    > --
    > Dmitry

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