Hi,
I'm trying to use FSL DMA engine to perform DMA transfer from
memory buffer obtained by kmalloc() to PCI memory. This is on
custom board based on P2020 running linux-2.6.35. The PCI
device is Altera FPGA, connected directly to SoC PCI-E controller.
01:00.0 Unassigned class [ff00]: Altera Corporation Unknown device
0004 (rev 01)
Subsystem: Altera Corporation Unknown device 0004
Control: I/O- Mem+ BusMaster- SpecCycle- MemWINV- VGASnoop-
ParErr- Stepping- SERR- FastB2B-
Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast
>TAbort- <TAbort- <MAbort- >SERR- <PERR-
Interrupt: pin A routed to IRQ 16
Region 0: Memory at c0000000 (32-bit, non-prefetchable)
[size=128K]
Capabilities: [50] Message Signalled Interrupts: Mask- 64bit+
Queue=0/0 Enable-
Address: 0000000000000000 Data: 0000
Capabilities: [78] Power Management version 3
Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA
PME(D0-,D1-,D2-,D3hot-,D3cold-)
Status: D0 PME-Enable- DSel=0 DScale=0 PME-
Capabilities: [80] Express Endpoint IRQ 0
Device: Supported: MaxPayload 256 bytes, PhantFunc 0,
ExtTag-
Device: Latency L0s <64ns, L1 <1us
Device: AtnBtn- AtnInd- PwrInd-
Device: Errors: Correctable- Non-Fatal- Fatal-
Unsupported-
Device: RlxdOrd+ ExtTag- PhantFunc- AuxPwr- NoSnoop+
Device: MaxPayload 128 bytes, MaxReadReq 512 bytes
Link: Supported Speed 2.5Gb/s, Width x1, ASPM L0s, Port 1
Link: Latency L0s unlimited, L1 unlimited
Link: ASPM Disabled RCB 64 bytes CommClk- ExtSynch-
Link: Speed 2.5Gb/s, Width x1
Capabilities: [100] Virtual Channel
I can successfully writel() to PCI memory via address obtained from
pci_ioremap_bar().
Here's my DMA transfer routine
static int dma_transfer(struct dma_chan *chan, void *dst, void *src,
size_t len)
{
int rc = 0;
dma_addr_t dma_src;
dma_addr_t dma_dst;
dma_cookie_t cookie;
struct completion cmp;
enum dma_status status;
enum dma_ctrl_flags flags = 0;
struct dma_device *dev = chan->device;
struct dma_async_tx_descriptor *tx = NULL;
unsigned long tmo = msecs_to_jiffies(FPGA_DMA_TIMEOUT_MS);
dma_src = dma_map_single(dev->dev, src, len, DMA_TO_DEVICE);
if (dma_mapping_error(dev->dev, dma_src)) {
printk(KERN_ERR "Failed to map src for DMA\n");
return -EIO;
}
dma_dst = (dma_addr_t)dst;
flags = DMA_CTRL_ACK |
DMA_COMPL_SRC_UNMAP_SINGLE |
DMA_COMPL_SKIP_DEST_UNMAP |
DMA_PREP_INTERRUPT;
tx = dev->device_prep_dma_memcpy(chan, dma_dst, dma_src, len, flags);
if (!tx) {
printk(KERN_ERR "%s: Failed to prepare DMA transfer\n",
__FUNCTION__);
dma_unmap_single(dev->dev, dma_src, len, DMA_TO_DEVICE);
return -ENOMEM;
}
init_completion(&cmp);
tx->callback = dma_callback;
tx->callback_param = &cmp;
cookie = tx->tx_submit(tx);
if (dma_submit_error(cookie)) {
printk(KERN_ERR "%s: Failed to start DMA transfer\n",
__FUNCTION__);
return -ENOMEM;
}
dma_async_issue_pending(chan);
tmo = wait_for_completion_timeout(&cmp, tmo);
status = dma_async_is_tx_complete(chan, cookie, NULL, NULL);
if (tmo == 0) {
printk(KERN_ERR "%s: Transfer timed out\n", __FUNCTION__);
rc = -ETIMEDOUT;
} else if (status != DMA_SUCCESS) {
printk(KERN_ERR "%s: Transfer failed: status is %s\n",
__FUNCTION__,
status == DMA_ERROR ? "error" : "in progress");
dev->device_control(chan, DMA_TERMINATE_ALL, 0);
rc = -EIO;
}
return rc;
}
The destination address is PCI memory address returned by
pci_ioremap_bar().
The transfer silently fails, destination buffer doesn't change
contents, but no
error condition is reported.
What am I doing wrong ?
Thanks a lot in advance.
Felix.
_______________________________________________
Linuxppc-dev mailing list
Linuxppc-dev@lists.ozlabs.org
https://lists.ozlabs.org/listinfo/linuxppc-dev
