diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/fault-injection/fault-injection.txt | 4 | ||||
| -rw-r--r-- | Documentation/input/multi-touch-protocol.txt | 48 | ||||
| -rw-r--r-- | Documentation/trace/ftrace-design.txt | 26 | ||||
| -rw-r--r-- | Documentation/trace/ftrace.txt | 2 |
4 files changed, 66 insertions, 14 deletions
diff --git a/Documentation/fault-injection/fault-injection.txt b/Documentation/fault-injection/fault-injection.txt index 079305640790..7be15e44d481 100644 --- a/Documentation/fault-injection/fault-injection.txt +++ b/Documentation/fault-injection/fault-injection.txt @@ -143,8 +143,8 @@ o provide a way to configure fault attributes failslab, fail_page_alloc, and fail_make_request use this way. Helper functions: - init_fault_attr_entries(entries, attr, name); - void cleanup_fault_attr_entries(entries); + init_fault_attr_dentries(entries, attr, name); + void cleanup_fault_attr_dentries(entries); - module parameters diff --git a/Documentation/input/multi-touch-protocol.txt b/Documentation/input/multi-touch-protocol.txt index a12ea3b586e6..8490480ce432 100644 --- a/Documentation/input/multi-touch-protocol.txt +++ b/Documentation/input/multi-touch-protocol.txt @@ -27,12 +27,30 @@ set of events/packets. A set of ABS_MT events with the desired properties is defined. The events are divided into categories, to allow for partial implementation. The -minimum set consists of ABS_MT_TOUCH_MAJOR, ABS_MT_POSITION_X and -ABS_MT_POSITION_Y, which allows for multiple fingers to be tracked. If the -device supports it, the ABS_MT_WIDTH_MAJOR may be used to provide the size -of the approaching finger. Anisotropy and direction may be specified with -ABS_MT_TOUCH_MINOR, ABS_MT_WIDTH_MINOR and ABS_MT_ORIENTATION. The -ABS_MT_TOOL_TYPE may be used to specify whether the touching tool is a +minimum set consists of ABS_MT_POSITION_X and ABS_MT_POSITION_Y, which +allows for multiple fingers to be tracked. If the device supports it, the +ABS_MT_TOUCH_MAJOR and ABS_MT_WIDTH_MAJOR may be used to provide the size +of the contact area and approaching finger, respectively. + +The TOUCH and WIDTH parameters have a geometrical interpretation; imagine +looking through a window at someone gently holding a finger against the +glass. You will see two regions, one inner region consisting of the part +of the finger actually touching the glass, and one outer region formed by +the perimeter of the finger. The diameter of the inner region is the +ABS_MT_TOUCH_MAJOR, the diameter of the outer region is +ABS_MT_WIDTH_MAJOR. Now imagine the person pressing the finger harder +against the glass. The inner region will increase, and in general, the +ratio ABS_MT_TOUCH_MAJOR / ABS_MT_WIDTH_MAJOR, which is always smaller than +unity, is related to the finger pressure. For pressure-based devices, +ABS_MT_PRESSURE may be used to provide the pressure on the contact area +instead. + +In addition to the MAJOR parameters, the oval shape of the finger can be +described by adding the MINOR parameters, such that MAJOR and MINOR are the +major and minor axis of an ellipse. Finally, the orientation of the oval +shape can be describe with the ORIENTATION parameter. + +The ABS_MT_TOOL_TYPE may be used to specify whether the touching tool is a finger or a pen or something else. Devices with more granular information may specify general shapes as blobs, i.e., as a sequence of rectangular shapes grouped together by an ABS_MT_BLOB_ID. Finally, for the few devices @@ -42,11 +60,9 @@ report finger tracking from hardware [5]. Here is what a minimal event sequence for a two-finger touch would look like: - ABS_MT_TOUCH_MAJOR ABS_MT_POSITION_X ABS_MT_POSITION_Y SYN_MT_REPORT - ABS_MT_TOUCH_MAJOR ABS_MT_POSITION_X ABS_MT_POSITION_Y SYN_MT_REPORT @@ -87,6 +103,12 @@ the contact. The ratio ABS_MT_TOUCH_MAJOR / ABS_MT_WIDTH_MAJOR approximates the notion of pressure. The fingers of the hand and the palm all have different characteristic widths [1]. +ABS_MT_PRESSURE + +The pressure, in arbitrary units, on the contact area. May be used instead +of TOUCH and WIDTH for pressure-based devices or any device with a spatial +signal intensity distribution. + ABS_MT_ORIENTATION The orientation of the ellipse. The value should describe a signed quarter @@ -170,6 +192,16 @@ There are a few devices that support trackingID in hardware. User space can make use of these native identifiers to reduce bandwidth and cpu usage. +Gestures +-------- + +In the specific application of creating gesture events, the TOUCH and WIDTH +parameters can be used to, e.g., approximate finger pressure or distinguish +between index finger and thumb. With the addition of the MINOR parameters, +one can also distinguish between a sweeping finger and a pointing finger, +and with ORIENTATION, one can detect twisting of fingers. + + Notes ----- diff --git a/Documentation/trace/ftrace-design.txt b/Documentation/trace/ftrace-design.txt index 239f14b2b55a..6a5a579126b0 100644 --- a/Documentation/trace/ftrace-design.txt +++ b/Documentation/trace/ftrace-design.txt @@ -1,5 +1,6 @@ function tracer guts ==================== + By Mike Frysinger Introduction ------------ @@ -173,14 +174,16 @@ void ftrace_graph_caller(void) unsigned long *frompc = &...; unsigned long selfpc = <return address> - MCOUNT_INSN_SIZE; - prepare_ftrace_return(frompc, selfpc); + /* passing frame pointer up is optional -- see below */ + prepare_ftrace_return(frompc, selfpc, frame_pointer); /* restore all state needed by the ABI */ } #endif -For information on how to implement prepare_ftrace_return(), simply look at -the x86 version. The only architecture-specific piece in it is the setup of +For information on how to implement prepare_ftrace_return(), simply look at the +x86 version (the frame pointer passing is optional; see the next section for +more information). The only architecture-specific piece in it is the setup of the fault recovery table (the asm(...) code). The rest should be the same across architectures. @@ -205,6 +208,23 @@ void return_to_handler(void) #endif +HAVE_FUNCTION_GRAPH_FP_TEST +--------------------------- + +An arch may pass in a unique value (frame pointer) to both the entering and +exiting of a function. On exit, the value is compared and if it does not +match, then it will panic the kernel. This is largely a sanity check for bad +code generation with gcc. If gcc for your port sanely updates the frame +pointer under different opitmization levels, then ignore this option. + +However, adding support for it isn't terribly difficult. In your assembly code +that calls prepare_ftrace_return(), pass the frame pointer as the 3rd argument. +Then in the C version of that function, do what the x86 port does and pass it +along to ftrace_push_return_trace() instead of a stub value of 0. + +Similarly, when you call ftrace_return_to_handler(), pass it the frame pointer. + + HAVE_FTRACE_NMI_ENTER --------------------- diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt index 8179692fbb90..bab3040da548 100644 --- a/Documentation/trace/ftrace.txt +++ b/Documentation/trace/ftrace.txt @@ -1625,7 +1625,7 @@ If I am only interested in sys_nanosleep and hrtimer_interrupt: # echo sys_nanosleep hrtimer_interrupt \ > set_ftrace_filter - # echo ftrace > current_tracer + # echo function > current_tracer # echo 1 > tracing_enabled # usleep 1 # echo 0 > tracing_enabled |