The following series implements a solution for a problem we have: lots of noise in the touchscreen of the Openmoko Neo1973/FreeRunner. This is the result of teamwork. We are using a small touchscreen filtering framework in kernel space for the S3C2410/S3C2442 touchscreen controllers. The filters can be used by other drivers as well (we have noticed a few drivers include averaging and some other custom filters). We do not want to port tslib to kernel space. The big difference is that in tslib you cannot give feedback to an interrupt handler. tslib does what it can, but we have the power in kernel space to do better. With the current implementation we try to get as many points as we need to in order to provide a clean input event that does not need further user-space mangling. If we fail to get a valid point after some time we just ignore the event. In our tests this approach has been performing very well. Some of us think it would be nice if a program can gather clean touchscreen data from /dev/inputX. Here is a document that explains the filters with links to source code that lives in our GIT repository and some videos The videos are not polished but they illustrate what we wish to show. https://wiki.openmoko.org/wiki/Touchscreen_Filters We hope this work is suitable for mainline inclusion. We will be waiting for your comments. Thanks, Nelson, on behalf of all who contributed to what is proposed in this email. drivers/input/touchscreen/Kconfig | 44 +++++ drivers/input/touchscreen/Makefile | 5 + drivers/input/touchscreen/ts_filter.c | 64 ++++++++ drivers/input/touchscreen/ts_filter_group.c | 221 ++++++++++++++++++++++++++ drivers/input/touchscreen/ts_filter_linear.c | 178 +++++++++++++++++++++ drivers/input/touchscreen/ts_filter_mean.c | 172 ++++++++++++++++++++ drivers/input/touchscreen/ts_filter_median.c | 215 +++++++++++++++++++++++++ include/linux/ts_filter.h | 56 +++++++ include/linux/ts_filter_group.h | 39 +++++ include/linux/ts_filter_linear.h | 64 ++++++++ include/linux/ts_filter_mean.h | 34 ++++ include/linux/ts_filter_median.h | 36 ++++ 12 files changed, 1128 insertions(+), 0 deletions(-) create mode 100644 drivers/input/touchscreen/ts_filter.c create mode 100644 drivers/input/touchscreen/ts_filter_group.c create mode 100644 drivers/input/touchscreen/ts_filter_linear.c create mode 100644 drivers/input/touchscreen/ts_filter_mean.c create mode 100644 drivers/input/touchscreen/ts_filter_median.c create mode 100644 include/linux/ts_filter.h create mode 100644 include/linux/ts_filter_group.h create mode 100644 include/linux/ts_filter_linear.h create mode 100644 include/linux/ts_filter_mean.h create mode 100644 include/linux/ts_filter_median.h -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
