Read EDID in DrmBackend
Documentation for the wonderful EDID format can be found at: http://read.pudn.com/downloads110/ebook/456020/E-EDID%20Standard.pdf In case the link breaks: wikipedia also has a good section on it. We read out the following information: * EISA code (3 characters) * serial number * monitor name (up to 12 characters) * physical size (stored in cm) Unfortunately the EDID information cannot be trusted at all. My 24" screen reports a sice of 16x9 cm. So we need to provide users a way to overwrite the broken data in an easy way through kwinrc [EdidOverwrite][EISA code/maker name][monitor name][serial number] PhysicalSize=trueWidthInMM,trueHeightInMM Unfortunately monitor name is not a sufficient enough identifier, that's why serial number is also used. This makes automatic distribution of overwrites difficult. But in the example above the monitor name is "SyncMaster" which is a rather broad field in Samsung :-( The extracted information from EDID is also used to set the corresponding fields in KWayland::Server::OutputInterface.
This commit is contained in:
Martin Gräßlin
parent
f4e2e0e2e9
commit
6d3fa98e09
2 changed files with 205 additions and 4 deletions
199
drm_backend.cpp
199
drm_backend.cpp
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@ -33,6 +33,10 @@ along with this program. If not, see <http://www.gnu.org/licenses/>.
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// KWayland
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#include <KWayland/Server/display.h>
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#include <KWayland/Server/output_interface.h>
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// KF5
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#include <KConfigGroup>
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#include <KLocalizedString>
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#include <KSharedConfig>
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// Qt
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#include <QSocketNotifier>
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#include <QPainter>
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@ -289,7 +293,7 @@ void DrmBackend::queryResources()
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drmOutput->m_mode = connector->modes[0];
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}
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drmOutput->m_connector = connector->connector_id;
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drmOutput->init();
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drmOutput->init(connector.data());
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connectedOutputs << drmOutput;
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}
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// check for outputs which got removed
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@ -600,12 +604,42 @@ void DrmOutput::cleanupBlackBuffer()
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}
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}
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void DrmOutput::init()
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void DrmOutput::init(drmModeConnector *connector)
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{
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initEdid(connector);
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m_savedCrtc.reset(drmModeGetCrtc(m_backend->fd(), m_crtcId));
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blank();
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m_waylandOutput.reset(waylandServer()->display()->createOutput());
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m_waylandOutput->setPhysicalSize(size() / 3.8);
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if (!m_edid.eisaId.isEmpty()) {
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m_waylandOutput->setManufacturer(QString::fromLatin1(m_edid.eisaId));
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} else {
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m_waylandOutput->setManufacturer(i18n("unknown"));
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}
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if (!m_edid.monitorName.isEmpty()) {
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QString model = QString::fromLatin1(m_edid.monitorName);
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if (!m_edid.serialNumber.isEmpty()) {
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model.append('/');
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model.append(QString::fromLatin1(m_edid.serialNumber));
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}
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m_waylandOutput->setModel(model);
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} else if (!m_edid.serialNumber.isEmpty()) {
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m_waylandOutput->setModel(QString::fromLatin1(m_edid.serialNumber));
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} else {
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m_waylandOutput->setModel(i18n("unknown"));
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}
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QSize physicalSize = !m_edid.physicalSize.isEmpty() ? m_edid.physicalSize : QSize(connector->mmWidth, connector->mmHeight);
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// the size might be completely borked. E.g. Samsung SyncMaster 2494HS reports 160x90 while in truth it's 520x292
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// as this information is used to calculate DPI info, it's going to result in everything being huge
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KSharedConfig::Ptr config = KSharedConfig::openConfig(KWIN_CONFIG);
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KConfigGroup group = config->group("EdidOverwrite").group(m_edid.eisaId).group(m_edid.monitorName).group(m_edid.serialNumber);
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if (group.hasKey("PhysicalSize")) {
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const QSize overwriteSize = group.readEntry("PhysicalSize", physicalSize);
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qCWarning(KWIN_CORE) << "Overwriting monitor physical size for" << m_edid.eisaId << "/" << m_edid.monitorName << "/" << m_edid.serialNumber << " from " << physicalSize << "to " << overwriteSize;
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physicalSize = overwriteSize;
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}
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m_waylandOutput->setPhysicalSize(physicalSize);
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m_waylandOutput->addMode(size());
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m_waylandOutput->create();
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}
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@ -631,6 +665,165 @@ bool DrmOutput::setMode(DrmBuffer *buffer)
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}
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}
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static bool verifyEdidHeader(drmModePropertyBlobPtr edid)
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{
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const uint8_t *data = reinterpret_cast<uint8_t*>(edid->data);
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if (data[0] != 0x00) {
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return false;
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}
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for (int i = 1; i < 7; ++i) {
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if (data[i] != 0xFF) {
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return false;
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}
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}
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if (data[7] != 0x00) {
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return false;
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}
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return true;
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}
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static QByteArray extractEisaId(drmModePropertyBlobPtr edid)
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{
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/*
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* From EDID standard section 3.4:
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* The ID Manufacturer Name field, shown in Table 3.5, contains a 2-byte representation of the monitor's
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* manufacturer. This is the same as the EISA ID. It is based on compressed ASCII, “0001=A” ... “11010=Z”.
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*
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* The table:
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* | Byte | Bit |
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* | | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
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* ----------------------------------------
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* | 1 | 0)| (4| 3 | 2 | 1 | 0)| (4| 3 |
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* | | * | Character 1 | Char 2|
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* ----------------------------------------
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* | 2 | 2 | 1 | 0)| (4| 3 | 2 | 1 | 0)|
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* | | Character2| Character 3 |
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* ----------------------------------------
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**/
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const uint8_t *data = reinterpret_cast<uint8_t*>(edid->data);
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static const uint offset = 0x8;
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char id[4];
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if (data[offset] >> 7) {
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// bit at position 7 is not a 0
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return QByteArray();
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}
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// shift two bits to right, and with 7 right most bits
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id[0] = 'A' + ((data[offset] >> 2) & 0x1f) -1;
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// for first byte: take last two bits and shift them 3 to left (000xx000)
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// for second byte: shift 5 bits to right and take 3 right most bits (00000xxx)
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// or both together
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id[1] = 'A' + (((data[offset] & 0x3) << 3) | ((data[offset + 1] >> 5) & 0x7)) - 1;
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// take five right most bits
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id[2] = 'A' + (data[offset + 1] & 0x1f) - 1;
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id[3] = '\0';
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return QByteArray(id);
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}
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static void extractMonitorDescriptorDescription(drmModePropertyBlobPtr blob, DrmOutput::Edid &edid)
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{
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// see section 3.10.3
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const uint8_t *data = reinterpret_cast<uint8_t*>(blob->data);
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static const uint offset = 0x36;
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static const uint blockLength = 18;
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for (int i = 0; i < 5; ++i) {
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const uint co = offset + i * blockLength;
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// Flag = 0000h when block used as descriptor
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if (data[co] != 0) {
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continue;
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}
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if (data[co + 1] != 0) {
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continue;
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}
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// Reserved = 00h when block used as descriptor
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if (data[co + 2] != 0) {
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continue;
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}
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/*
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* FFh: Monitor Serial Number - Stored as ASCII, code page # 437, ≤ 13 bytes.
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* FEh: ASCII String - Stored as ASCII, code page # 437, ≤ 13 bytes.
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* FDh: Monitor range limits, binary coded
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* FCh: Monitor name, stored as ASCII, code page # 437
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* FBh: Descriptor contains additional color point data
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* FAh: Descriptor contains additional Standard Timing Identifications
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* F9h - 11h: Currently undefined
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* 10h: Dummy descriptor, used to indicate that the descriptor space is unused
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* 0Fh - 00h: Descriptor defined by manufacturer.
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*/
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if (data[co + 3] == 0xfc && edid.monitorName.isEmpty()) {
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edid.monitorName = QByteArray((const char *)(&data[co + 5]), 12).trimmed();
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}
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if (data[co + 3] == 0xfe) {
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const QByteArray id = QByteArray((const char *)(&data[co + 5]), 12).trimmed();
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if (!id.isEmpty()) {
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edid.eisaId = id;
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}
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}
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if (data[co + 3] == 0xff) {
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edid.serialNumber = QByteArray((const char *)(&data[co + 5]), 12).trimmed();
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}
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}
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}
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static QByteArray extractSerialNumber(drmModePropertyBlobPtr edid)
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{
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// see section 3.4
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const uint8_t *data = reinterpret_cast<uint8_t*>(edid->data);
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static const uint offset = 0x0C;
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/*
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* The ID serial number is a 32-bit serial number used to differentiate between individual instances of the same model
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* of monitor. Its use is optional. When used, the bit order for this field follows that shown in Table 3.6. The EDID
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* structure Version 1 Revision 1 and later offer a way to represent the serial number of the monitor as an ASCII string
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* in a separate descriptor block.
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*/
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uint32_t serialNumber = 0;
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serialNumber = (uint32_t) data[offset + 0];
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serialNumber |= (uint32_t) data[offset + 1] << 8;
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serialNumber |= (uint32_t) data[offset + 2] << 16;
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serialNumber |= (uint32_t) data[offset + 3] << 24;
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if (serialNumber == 0) {
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return QByteArray();
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}
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return QByteArray::number(serialNumber);
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}
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static QSize extractPhysicalSize(drmModePropertyBlobPtr edid)
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{
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const uint8_t *data = reinterpret_cast<uint8_t*>(edid->data);
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return QSize(data[0x15], data[0x16]) * 10;
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}
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void DrmOutput::initEdid(drmModeConnector *connector)
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{
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ScopedDrmPointer<_drmModePropertyBlob, &drmModeFreePropertyBlob> edid;
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for (int i = 0; i < connector->count_props; ++i) {
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ScopedDrmPointer<_drmModeProperty, &drmModeFreeProperty> property(drmModeGetProperty(m_backend->fd(), connector->props[i]));
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if (!property) {
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continue;
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}
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if ((property->flags & DRM_MODE_PROP_BLOB) && qstrcmp(property->name, "EDID") == 0) {
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edid.reset(drmModeGetPropertyBlob(m_backend->fd(), connector->prop_values[i]));
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}
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}
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if (!edid) {
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return;
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}
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// for documentation see: http://read.pudn.com/downloads110/ebook/456020/E-EDID%20Standard.pdf
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if (edid->length < 128) {
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return;
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}
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if (!verifyEdidHeader(edid.data())) {
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return;
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}
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m_edid.eisaId = extractEisaId(edid.data());
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m_edid.serialNumber = extractSerialNumber(edid.data());
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// parse monitor descriptor description
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extractMonitorDescriptorDescription(edid.data(), m_edid);
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m_edid.physicalSize = extractPhysicalSize(edid.data());
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}
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DrmBuffer::DrmBuffer(DrmBackend *backend, const QSize &size)
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: m_backend(backend)
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, m_size(size)
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@ -110,13 +110,19 @@ private:
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class DrmOutput
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{
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public:
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struct Edid {
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QByteArray eisaId;
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QByteArray monitorName;
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QByteArray serialNumber;
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QSize physicalSize;
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};
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virtual ~DrmOutput();
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void showCursor(DrmBuffer *buffer);
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void hideCursor();
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void moveCursor(const QPoint &globalPos);
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bool present(DrmBuffer *buffer);
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void pageFlipped();
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void init();
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void init(drmModeConnector *connector);
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void restoreSaved();
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void blank();
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@ -128,6 +134,7 @@ private:
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DrmOutput(DrmBackend *backend);
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void cleanupBlackBuffer();
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bool setMode(DrmBuffer *buffer);
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void initEdid(drmModeConnector *connector);
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DrmBackend *m_backend;
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QPoint m_globalPos;
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@ -142,6 +149,7 @@ private:
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drmModeFreeCrtc(ptr);
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}
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};
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Edid m_edid;
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QScopedPointer<_drmModeCrtc, CrtcCleanup> m_savedCrtc;
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QScopedPointer<KWayland::Server::OutputInterface> m_waylandOutput;
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};
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