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dptx: Optimized immediate I2C read transaction.

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The 16-byte chunking is already done by XDptx_AuxCommon, so there is no need to
do it in XDptx_IicRead.

Signed-off-by: Andrei-Liviu Simion <andrei.simion@xilinx.com>
This commit is contained in:
Andrei-Liviu Simion 2014-11-03 17:58:56 -08:00 • committed by Suneel Garapati
parent 67640948cf
commit d431d30835
1 changed files with 22 additions and 25 deletions
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47
XilinxProcessorIPLib/drivers/dptx/src/xdptx.c
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@ -797,9 +797,9 @@ u32 XDptx_AuxWrite(XDptx *InstancePtr, u32 DpcdAddress, u32 BytesToWrite,
/******************************************************************************/
/**
* This function performs an I2C read over the AUX channel. The read message
* will be divided into multiple transactions which read a maximum of 16 bytes
* each. The segment pointer is automatically incremented and the offset is
* calibrated as needed. E.g. For an overall offset of:
* will be divided into multiple transactions if the requested data spans
* multiple segments. The segment pointer is automatically incremented and the
* offset is calibrated as needed. E.g. For an overall offset of:
* - 128, an I2C read is done on segptr=0; offset=128.
* - 256, an I2C read is done on segptr=1; offset=0.
* - 384, an I2C read is done on segptr=1; offset=128.
@ -862,14 +862,11 @@ u32 XDptx_IicRead(XDptx *InstancePtr, u8 IicAddress, u16 Offset,
return Status;
}
/* Send I2C read message in 16 byte chunks. */
/* Send I2C read message. Multiple transactions are required if the
* requested data spans multiple segments. */
while (BytesLeft > 0) {
/* Read a maximum of 16 bytes. */
if ((NumBytesLeftInSeg >= 16) && (BytesLeft >= 16)) {
CurrBytesToRead = 16;
}
/* Read the remaining number of bytes as requested. */
else if (NumBytesLeftInSeg >= BytesLeft) {
if (NumBytesLeftInSeg >= BytesLeft) {
CurrBytesToRead = BytesLeft;
}
/* Read the remaining data in the current segment boundary. */
@ -890,31 +887,31 @@ u32 XDptx_IicRead(XDptx *InstancePtr, u8 IicAddress, u16 Offset,
return Status;
}
/* I2C read of 16 bytes. */
/* Previous I2C read was done on the remaining data in the
* current segment; prepare for next read. */
if (BytesLeft > CurrBytesToRead) {
BytesLeft -= CurrBytesToRead;
Offset += CurrBytesToRead;
ReadData += CurrBytesToRead;
NumBytesLeftInSeg -= CurrBytesToRead;
/* Increment the segment pointer to access more I2C
* address space, if required. */
if (BytesLeft > 0) {
NumBytesLeftInSeg = 256;
Offset %= 256;
SegPtr++;
Status = XDptx_IicWrite(InstancePtr,
XDPTX_SEGPTR_ADDR, 1, &SegPtr);
if (Status != XST_SUCCESS) {
return Status;
}
}
}
/* Last I2C read. */
else {
BytesLeft = 0;
}
/* Increment the segment pointer to access more I2C address
* space, if required. */
if ((NumBytesLeftInSeg == 0) && (BytesLeft > 0)) {
SegPtr++;
Offset %= 256;
NumBytesLeftInSeg = 256;
Status = XDptx_IicWrite(InstancePtr, XDPTX_SEGPTR_ADDR,
1, &SegPtr);
if (Status != XST_SUCCESS) {
return Status;
}
}
}
/* Reset the segment pointer to 0. */