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dptx: Improved remote DPCD reads/writes to automatically work on 16-byte chunks.

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Some monitors don't support sideband messages with AUX reads greater than 16
bytes. This improvement breaks up the higher-level read/write request into
multiple reads/writes that work with up to 16 bytes in size.

These higher-level remote DPCD read/write functions also serve as a wrapper for
an AUX read/write in case that the link count total is equal to 1 (a read/write
request to the RX device directly connected to the TX (not "remote")).

Signed-off-by: Andrei-Liviu Simion <andrei.simion@xilinx.com>
This commit is contained in:
Andrei-Liviu Simion 2014-10-30 12:52:59 -07:00 • committed by Suneel Garapati
parent 327bbeb10b
commit 0cd5afb0fd
2 changed files with 85 additions and 0 deletions
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7
XilinxProcessorIPLib/drivers/dptx/src/xdptx.h
View file

@ -833,6 +833,13 @@ u32 XDptx_DiscoverTopology(XDptx *InstancePtr);
u32 XDptx_FindAccessibleDpDevices(XDptx *InstancePtr, u8 LinkCountTotal,
u8 *RelativeAddress);
/* xdptx_mst.c: Multi-stream transport (MST) functions for communicating
* with downstream DisplayPort devices. */
u32 XDptx_RemoteDpcdRead(XDptx *InstancePtr, u8 LinkCountTotal,
u8 *RelativeAddress, u32 DpcdAddress, u32 BytesToRead, u8 *ReadData);
u32 XDptx_RemoteDpcdWrite(XDptx *InstancePtr, u8 LinkCountTotal,
u8 *RelativeAddress, u32 DpcdAddress, u32 BytesToWrite, u8 *WriteData);
/* xdptx_mst.c: Multi-stream transport (MST) functions related to MST stream
* allocation. */
u32 XDptx_AllocatePayloadStreams(XDptx *InstancePtr);

78
XilinxProcessorIPLib/drivers/dptx/src/xdptx_mst.c
View file

@ -706,6 +706,84 @@ u32 XDptx_FindAccessibleDpDevices(XDptx *InstancePtr, u8 LinkCountTotal,
return XST_SUCCESS;
}
u32 XDptx_RemoteDpcdRead(XDptx *InstancePtr, u8 LinkCountTotal,
u8 *RelativeAddress, u32 DpcdAddress, u32 BytesToRead, u8 *ReadData)
{
u32 Status;
if (LinkCountTotal == 1) {
Status = XDptx_AuxRead(InstancePtr, DpcdAddress, BytesToRead,
ReadData);
}
else {
u32 BytesLeft = BytesToRead;
while (BytesLeft > 0) {
if (BytesLeft > 16) {
Status = XDptx_SendSbMsgRemoteDpcdRead(
InstancePtr, LinkCountTotal,
RelativeAddress, DpcdAddress, 16,
ReadData);
BytesLeft -= 16;
DpcdAddress += 16;
ReadData += 16;
}
else {
Status = XDptx_SendSbMsgRemoteDpcdRead(
InstancePtr, LinkCountTotal,
RelativeAddress, DpcdAddress, BytesLeft,
ReadData);
BytesLeft = 0;
}
if (Status != XST_SUCCESS) {
/* The AUX read transaction failed. */
return Status;
}
}
}
return Status;
}
u32 XDptx_RemoteDpcdWrite(XDptx *InstancePtr, u8 LinkCountTotal,
u8 *RelativeAddress, u32 DpcdAddress, u32 BytesToWrite, u8 *WriteData)
{
u32 Status;
if (LinkCountTotal == 1) {
Status = XDptx_AuxWrite(InstancePtr, DpcdAddress, BytesToWrite,
WriteData);
}
else {
u32 BytesLeft = BytesToWrite;
while (BytesLeft > 0) {
if (BytesLeft > 16) {
Status = XDptx_SendSbMsgRemoteDpcdWrite(
InstancePtr, LinkCountTotal,
RelativeAddress, DpcdAddress, 16,
WriteData);
BytesLeft -= 16;
DpcdAddress += 16;
WriteData += 16;
}
else {
Status = XDptx_SendSbMsgRemoteDpcdWrite(
InstancePtr, LinkCountTotal,
RelativeAddress, DpcdAddress, BytesLeft,
WriteData);
BytesLeft = 0;
}
if (Status != XST_SUCCESS) {
/* The AUX read transaction failed. */
return Status;
}
}
}
return Status;
}
/******************************************************************************/
/**
* This function will allocate bandwidth for all enabled stream.