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DDC: send VCP writes twice #362

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DDC: send VCP writes twice #362

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8 changes: 5 additions & 3 deletions FineTune/Audio/DDC/DDCService.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -137,16 +137,18 @@ final class DDCService: @unchecked Sendable {
}

/// Writes a DDC packet without reading a response.
///
/// Send all write cycles; some displays only apply the second write.
private func i2cWrite(packet: [UInt8]) throws {
var lastResult: IOReturn = kIOReturnError
for _ in 0..<numWriteCycles {
usleep(writeSleepTime)
let result = packet.withUnsafeBufferPointer { buf in
lastResult = packet.withUnsafeBufferPointer { buf in
IOAVServiceLoader.writeI2C(service: service, chipAddress: chipAddress,
dataAddress: writeAddress, buffer: buf.baseAddress!, size: UInt32(buf.count))
}
if result == kIOReturnSuccess { return }
}
throw DDCError.writeFailed(kIOReturnError)
guard lastResult == kIOReturnSuccess else { throw DDCError.writeFailed(lastResult) }
}

// MARK: - VCP Commands
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