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evdevtouch: Don't try to keep reading on EAGAIN

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This stops touching the screen (and not moving) consuming 80-90% CPU.
The mtdev and non-mtdev codepaths have been separated for additional clarity.

Change-Id: I0559a6bd80dab961fdb4a83ad50860a9aec6445c
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>
This commit is contained in:
Robin Burchell 2014-01-22 11:49:16 +01:00 committed by The Qt Project
parent ac29884772
commit a4e703764e
1 changed files with 47 additions and 26 deletions
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57
src/platformsupport/input/evdevtouch/qevdevtouch.cpp
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@ -345,19 +345,50 @@ QEvdevTouchScreenHandler::~QEvdevTouchScreenHandler()
void QEvdevTouchScreenHandler::readData()
{
::input_event buffer[32];
int events = 0;
#if !defined(QT_NO_MTDEV)
forever {
do {
events = mtdev_get(m_mtdev, m_fd, buffer, sizeof(buffer) / sizeof(::input_event));
// keep trying mtdev_get if we get interrupted. note that we do not
// (and should not) handle EAGAIN; EAGAIN means that reading would
// block and we'll get back here later to try again anyway.
} while (events == -1 && errno == EINTR);
// 0 events is EOF, -1 means error, handle both in the same place
if (events <= 0)
goto err;
// process our shiny new events
for (int i = 0; i < events; ++i)
d->processInputEvent(&buffer[i]);
// and try to get more
}
#else
int n = 0;
for (; ;) {
#if !defined(QT_NO_MTDEV)
int result = mtdev_get(m_mtdev, m_fd, buffer, sizeof(buffer) / sizeof(::input_event));
if (result > 0)
result *= sizeof(::input_event);
#else
int result = QT_READ(m_fd, reinterpret_cast<char*>(buffer) + n, sizeof(buffer) - n);
events = QT_READ(m_fd, reinterpret_cast<char*>(buffer) + n, sizeof(buffer) - n);
if (events <= 0)
goto err;
n += events;
if (n % sizeof(::input_event) == 0)
break;
}
n /= sizeof(::input_event);
for (int i = 0; i < n; ++i)
d->processInputEvent(&buffer[i]);
#endif
if (!result) {
return;
err:
if (!events) {
qWarning("evdevtouch: Got EOF from input device");
return;
} else if (result < 0) {
} else if (events < 0) {
if (errno != EINTR && errno != EAGAIN) {
qErrnoWarning(errno, "evdevtouch: Could not read from input device");
if (errno == ENODEV) { // device got disconnected -> stop reading
@ -368,19 +399,9 @@ void QEvdevTouchScreenHandler::readData()
}
return;
}
} else {
n += result;
if (n % sizeof(::input_event) == 0)
break;
}
}
n /= sizeof(::input_event);
for (int i = 0; i < n; ++i)
d->processInputEvent(&buffer[i]);
}
void QEvdevTouchScreenData::addTouchPoint(const Contact &contact, Qt::TouchPointStates *combinedStates)
{
QWindowSystemInterface::TouchPoint tp;