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eglfs: kms: Make threaded atomic drm work

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The atomic modesetting support was not prepared for page flips being
issued from different (per-screen) threads.

This could be seen with the threaded render loop of Qt Quick: having a
QQuickWindow per screen means having a dedicated render thread for each
screen. QKmsDevice used simply instance variables to keep track of the
request. This leads to the commit failing with EBUSY sooner or later.

Make the atomic request and related variables thread local.

This prevents failing drmModeAtomicCommit() with 2 or more screens and
the threaded render loop. It does not fix other potential issues when
waiting for page flips to complete, that is to be tackled separately.

Task-number: QTBUG-74953
Change-Id: I2dac10d5e9bdc0cb556ac78c9643c96d40d692e4
Reviewed-by: Johan Helsing <johan.helsing@qt.io>
(cherry picked from commit 5bd48047de4abecc47187d938c5e6ed8b8304aaf)
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>
This commit is contained in:
Laszlo Agocs 2019-11-08 11:41:16 +01:00
parent d1b009cbbb
commit 5705133066
4 changed files with 50 additions and 41 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

58
src/platformsupport/kmsconvenience/qkmsdevice.cpp
View File

@ -522,10 +522,6 @@ QKmsDevice::QKmsDevice(QKmsScreenConfig *screenConfig, const QString &path)
, m_path(path)
, m_dri_fd(-1)
, m_has_atomic_support(false)
#if QT_CONFIG(drm_atomic)
, m_atomic_request(nullptr)
, m_previous_request(nullptr)
#endif
, m_crtc_allocator(0)
{
if (m_path.isEmpty()) {
@ -541,7 +537,7 @@ QKmsDevice::QKmsDevice(QKmsScreenConfig *screenConfig, const QString &path)
QKmsDevice::~QKmsDevice()
{
#if QT_CONFIG(drm_atomic)
atomicReset();
threadLocalAtomicReset();
#endif
}
@ -881,39 +877,51 @@ bool QKmsDevice::hasAtomicSupport()
}
#if QT_CONFIG(drm_atomic)
drmModeAtomicReq * QKmsDevice::atomic_request()
drmModeAtomicReq *QKmsDevice::threadLocalAtomicRequest()
{
if (!m_atomic_request && m_has_atomic_support)
m_atomic_request = drmModeAtomicAlloc();
if (!m_has_atomic_support)
return nullptr;
return m_atomic_request;
AtomicReqs &a(m_atomicReqs.localData());
if (!a.request)
a.request = drmModeAtomicAlloc();
return a.request;
}
bool QKmsDevice::atomicCommit(void *user_data)
bool QKmsDevice::threadLocalAtomicCommit(void *user_data)
{
if (m_atomic_request) {
int ret = drmModeAtomicCommit(m_dri_fd, m_atomic_request,
DRM_MODE_ATOMIC_NONBLOCK | DRM_MODE_PAGE_FLIP_EVENT | DRM_MODE_ATOMIC_ALLOW_MODESET, user_data);
if (!m_has_atomic_support)
return false;
if (ret) {
qWarning("Failed to commit atomic request (code=%d)", ret);
return false;
}
AtomicReqs &a(m_atomicReqs.localData());
if (!a.request)
return false;
m_previous_request = m_atomic_request;
m_atomic_request = nullptr;
int ret = drmModeAtomicCommit(m_dri_fd, a.request,
DRM_MODE_ATOMIC_NONBLOCK | DRM_MODE_PAGE_FLIP_EVENT | DRM_MODE_ATOMIC_ALLOW_MODESET,
user_data);
return true;
if (ret) {
qWarning("Failed to commit atomic request (code=%d)", ret);
return false;
}
return false;
a.previous_request = a.request;
a.request = nullptr;
return true;
}
void QKmsDevice::atomicReset()
void QKmsDevice::threadLocalAtomicReset()
{
if (m_previous_request) {
drmModeAtomicFree(m_previous_request);
m_previous_request = nullptr;
if (!m_has_atomic_support)
return;
AtomicReqs &a(m_atomicReqs.localData());
if (a.previous_request) {
drmModeAtomicFree(a.previous_request);
a.previous_request = nullptr;
}
}
#endif

15
src/platformsupport/kmsconvenience/qkmsdevice_p.h
View File

@ -57,6 +57,7 @@
#include <qpa/qplatformscreen.h>
#include <QtCore/QMap>
#include <QtCore/QVariant>
#include <QtCore/QThreadStorage>
#include <xf86drm.h>
#include <xf86drmMode.h>
@ -238,10 +239,9 @@ public:
bool hasAtomicSupport();
#if QT_CONFIG(drm_atomic)
bool atomicCommit(void *user_data);
void atomicReset();
drmModeAtomicReq *atomic_request();
drmModeAtomicReq *threadLocalAtomicRequest();
bool threadLocalAtomicCommit(void *user_data);
void threadLocalAtomicReset();
#endif
void createScreens();
@ -281,8 +281,11 @@ protected:
bool m_has_atomic_support;
#if QT_CONFIG(drm_atomic)
drmModeAtomicReq *m_atomic_request;
drmModeAtomicReq *m_previous_request;
struct AtomicReqs {
drmModeAtomicReq *request = nullptr;
drmModeAtomicReq *previous_request = nullptr;
};
QThreadStorage<AtomicReqs> m_atomicReqs;
#endif
quint32 m_crtc_allocator;

16
src/plugins/platforms/eglfs/deviceintegration/eglfs_kms/qeglfskmsgbmscreen.cpp
View File

@ -243,7 +243,7 @@ void QEglFSKmsGbmScreen::ensureModeSet(uint32_t fb)
if (device()->hasAtomicSupport()) {
#if QT_CONFIG(drm_atomic)
drmModeAtomicReq *request = device()->atomic_request();
drmModeAtomicReq *request = device()->threadLocalAtomicRequest();
if (request) {
drmModeAtomicAddProperty(request, op.connector_id, op.crtcIdPropertyId, op.crtc_id);
drmModeAtomicAddProperty(request, op.crtc_id, op.modeIdPropertyId, op.mode_blob_id);
@ -287,8 +287,7 @@ void QEglFSKmsGbmScreen::waitForFlip()
}
#if QT_CONFIG(drm_atomic)
if (device()->hasAtomicSupport())
device()->atomicReset();
device()->threadLocalAtomicReset();
#endif
}
@ -324,16 +323,16 @@ void QEglFSKmsGbmScreen::flip()
if (device()->hasAtomicSupport()) {
#if QT_CONFIG(drm_atomic)
drmModeAtomicReq *request = device()->atomic_request();
drmModeAtomicReq *request = device()->threadLocalAtomicRequest();
if (request) {
drmModeAtomicAddProperty(request, op.eglfs_plane->id, op.eglfs_plane->framebufferPropertyId, fb->fb);
drmModeAtomicAddProperty(request, op.eglfs_plane->id, op.eglfs_plane->crtcPropertyId, op.crtc_id);
drmModeAtomicAddProperty(request, op.eglfs_plane->id, op.eglfs_plane->srcwidthPropertyId,
output().size.width() << 16);
op.size.width() << 16);
drmModeAtomicAddProperty(request, op.eglfs_plane->id, op.eglfs_plane->srcXPropertyId, 0);
drmModeAtomicAddProperty(request, op.eglfs_plane->id, op.eglfs_plane->srcYPropertyId, 0);
drmModeAtomicAddProperty(request, op.eglfs_plane->id, op.eglfs_plane->srcheightPropertyId,
output().size.height() << 16);
op.size.height() << 16);
drmModeAtomicAddProperty(request, op.eglfs_plane->id, op.eglfs_plane->crtcXPropertyId, 0);
drmModeAtomicAddProperty(request, op.eglfs_plane->id, op.eglfs_plane->crtcYPropertyId, 0);
drmModeAtomicAddProperty(request, op.eglfs_plane->id, op.eglfs_plane->crtcwidthPropertyId,
@ -368,7 +367,7 @@ void QEglFSKmsGbmScreen::flip()
if (device()->hasAtomicSupport()) {
#if QT_CONFIG(drm_atomic)
drmModeAtomicReq *request = device()->atomic_request();
drmModeAtomicReq *request = device()->threadLocalAtomicRequest();
if (request) {
drmModeAtomicAddProperty(request, d.screen->output().eglfs_plane->id,
d.screen->output().eglfs_plane->framebufferPropertyId, fb->fb);
@ -391,8 +390,7 @@ void QEglFSKmsGbmScreen::flip()
}
#if QT_CONFIG(drm_atomic)
if (device()->hasAtomicSupport())
device()->atomicCommit(this);
device()->threadLocalAtomicCommit(this);
#endif
}

2
src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_support/qeglfskmsintegration.cpp
View File

@ -140,7 +140,7 @@ void *QEglFSKmsIntegration::nativeResourceForIntegration(const QByteArray &name)
#if QT_CONFIG(drm_atomic)
if (name == QByteArrayLiteral("dri_atomic_request") && m_device)
return (void *) (qintptr) m_device->atomic_request();
return (void *) (qintptr) m_device->threadLocalAtomicRequest();
#endif
return nullptr;
}