| Message ID | 1424960348.4444.19.camel@xylophone.i.decadent.org.uk |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | David Miller |
| Headers | show |
Hello. On 02/26/2015 05:19 PM, Ben Hutchings wrote: > In case of RX ring underrun (RDE), we attempt to reset the software > descriptor pointers (dirty_rx and cur_rx) to match where the hardware > will read the next descriptor from, as that might not be the first > dirty descriptor. This relies on reading RDFAR, but that register > doesn't exist on all supported chips - specifically, not on the R-Car > chips. This will result in unpredictable behaviour on those chips > after an RDE. > Make this pointer reset conditional and assume that it isn't needed on > the R-Car chips. This fix also assumes that RDFAR is never exposed at > offset 0 in the memory map - this is currently true, and a subsequent > commit will fix the ambiguity between offset 0 and no-offset in the > register offset maps. > Fixes: 79fba9f51755 ("net: sh_eth: fix the rxdesc pointer when rx ...") > Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk> > --- > I was able to trigger RDE by adding a udelay(10) to the loop in > sh_eth_rx() (limiting RX to <100,000 pps) and sending minimum size > frames with pktgen (~160,000 pps at 100M). The RDE was recorded in the > netdev stats. After the RDE and recover I could still pass traffic > successfully so no extra code appears to be needed for this chip. Thank you for at last tackling this; it was on my agenda for a long time... WBR, Sergei -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/net/ethernet/renesas/sh_eth.c b/drivers/net/ethernet/renesas/sh_eth.c index 2bc0be45c751..ed67951f5271 100644 --- a/drivers/net/ethernet/renesas/sh_eth.c +++ b/drivers/net/ethernet/renesas/sh_eth.c @@ -1540,7 +1540,7 @@ static int sh_eth_rx(struct net_device *ndev, u32 intr_status, int *quota) /* If we don't need to check status, don't. -KDU */ if (!(sh_eth_read(ndev, EDRRR) & EDRRR_R)) { /* fix the values for the next receiving if RDE is set */ - if (intr_status & EESR_RDE) { + if (intr_status & EESR_RDE && mdp->reg_offset[RDFAR] != 0) { u32 count = (sh_eth_read(ndev, RDFAR) - sh_eth_read(ndev, RDLAR)) >> 4;
In case of RX ring underrun (RDE), we attempt to reset the software descriptor pointers (dirty_rx and cur_rx) to match where the hardware will read the next descriptor from, as that might not be the first dirty descriptor. This relies on reading RDFAR, but that register doesn't exist on all supported chips - specifically, not on the R-Car chips. This will result in unpredictable behaviour on those chips after an RDE. Make this pointer reset conditional and assume that it isn't needed on the R-Car chips. This fix also assumes that RDFAR is never exposed at offset 0 in the memory map - this is currently true, and a subsequent commit will fix the ambiguity between offset 0 and no-offset in the register offset maps. Fixes: 79fba9f51755 ("net: sh_eth: fix the rxdesc pointer when rx ...") Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk> --- I was able to trigger RDE by adding a udelay(10) to the loop in sh_eth_rx() (limiting RX to <100,000 pps) and sending minimum size frames with pktgen (~160,000 pps at 100M). The RDE was recorded in the netdev stats. After the RDE and recover I could still pass traffic successfully so no extra code appears to be needed for this chip. Ben. drivers/net/ethernet/renesas/sh_eth.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)