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[AVR] Send USB ZLP if required #5802

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Merged
merged 2 commits into from
Mar 16, 2017
Merged

[AVR] Send USB ZLP if required #5802

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1686f78
Revert "Subtract one from USB_EP_SIZE in USB_SendSpace"
cmaglie Jan 4, 2017
a540126
[AVR] USB send ZLP when needed
cmaglie Jan 4, 2017
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26 changes: 19 additions & 7 deletions hardware/arduino/avr/cores/arduino/USBCore.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -256,9 +256,7 @@ u8 USB_SendSpace(u8 ep)
LockEP lock(ep);
if (!ReadWriteAllowed())
return 0;
// subtract 1 from the EP size to never send a full packet,
// this avoids dealing with ZLP's in USB_Send
return USB_EP_SIZE - 1 - FifoByteCount();
return USB_EP_SIZE - FifoByteCount();
}

// Blocking Send of data to an endpoint
Expand All @@ -275,7 +273,9 @@ int USB_Send(u8 ep, const void* d, int len)
int r = len;
const u8* data = (const u8*)d;
u8 timeout = 250; // 250ms timeout on send? TODO
while (len)
bool sendZlp = false;

while (len || sendZlp)
{
u8 n = USB_SendSpace(ep);
if (n == 0)
Expand All @@ -286,13 +286,16 @@ int USB_Send(u8 ep, const void* d, int len)
continue;
}

if (n > len)
if (n > len) {
n = len;
}

{
LockEP lock(ep);
// Frame may have been released by the SOF interrupt handler
if (!ReadWriteAllowed())
continue;

len -= n;
if (ep & TRANSFER_ZERO)
{
Expand All @@ -309,8 +312,17 @@ int USB_Send(u8 ep, const void* d, int len)
while (n--)
Send8(*data++);
}
if (!ReadWriteAllowed() || ((len == 0) && (ep & TRANSFER_RELEASE))) // Release full buffer

if (sendZlp) {
ReleaseTX();
sendZlp = false;
} else if (!ReadWriteAllowed()) { // ...release if buffer is full...
ReleaseTX();
if (len == 0) sendZlp = true;
} else if ((len == 0) && (ep & TRANSFER_RELEASE)) { // ...or if forced with TRANSFER_RELEASE
// XXX: TRANSFER_RELEASE is never used can be removed?
ReleaseTX();
}
}
}
TXLED1; // light the TX LED
Expand Down Expand Up @@ -475,7 +487,7 @@ static
bool SendConfiguration(int maxlen)
{
// Count and measure interfaces
InitControl(0);
InitControl(0);
u8 interfaces = SendInterfaces();
ConfigDescriptor config = D_CONFIG(_cmark + sizeof(ConfigDescriptor),interfaces);

Expand Down