Kok, Auke wrote: > David Daney wrote: >> I am running the e100 driver on a MIPS 4KEc system (32 bit mips with >> non-coherent DMA). There was a problem where received packets would >> get 'stuck' for several seconds at a time and then be released all at >> once. >> >> The cause was that if an interrupt were received when no RX packets >> were available, the status for the receive buffer would be stuck in >> the cache, so when the next interrupt arrived the old status value was >> read (indicating no packets available) instead of the new value. >> >> The fix is to call pci_dma_sync_single_for_device on the RX if the >> packet is not available to invalidate the cache so that at the next >> interrupt valid status is returned. >> >> The driver currently calls pci_dma_sync_single_for_cpu before reading >> the status, and this is indeed needed for cases like the R10000 CPU >> where the cache can be polluted by speculative execution, but for most >> machines it is a nop. >> >> The patch was tested on 2.6.17-rc4 on a MIPS 4KEc. > > > lol, that's a bit old :) >
It was a typo. The real version is 2.6.27-rc4 (aka the HEAD). The bug is present on the HEAD. Sorry for the confusion. David Daney. > A LOT of work has gone into 2.6.26+'s version of e100 that addresses > specifically > non-coherent DMA machines, including a patch that looks very close to what you > write below here. > > can you test the latest git tree and see if you still need (a modified or > updated > version) of your patch? > > I know for sure that the guys maintaining e100 do not have anything close to > your > system, so they can't test that. > > Cheers, > > Auke > >> Signed-off-by: David Daney <[EMAIL PROTECTED]> >> --- >> drivers/net/e100.c | 5 +++++ >> 1 files changed, 5 insertions(+), 0 deletions(-) >> >> diff --git a/drivers/net/e100.c b/drivers/net/e100.c >> index 19d32a2..fb8d551 100644 >> --- a/drivers/net/e100.c >> +++ b/drivers/net/e100.c >> @@ -1840,6 +1840,11 @@ static int e100_rx_indicate(struct nic *nic, struct >> rx *rx, >> >> if (readb(&nic->csr->scb.status) & rus_no_res) >> nic->ru_running = RU_SUSPENDED; >> + /* We are done looking at the buffer. Prepare it for >> + * more DMA. */ >> + pci_dma_sync_single_for_device(nic->pdev, rx->dma_addr, >> + sizeof(struct rfd), >> + PCI_DMA_FROMDEVICE); >> return -ENODATA; >> } >> > ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ E1000-devel mailing list E1000-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/e1000-devel
