Hello! Thank you for your review! > From: Sergei Shtylyov, Sent: Tuesday, July 21, 2020 2:15 AM > > Hello! > > On 7/20/20 2:58 PM, Yoshihiro Shimoda wrote: > > > According to the report of [1], this driver is possible to cause > > the following error in ravb_tx_timeout_work(). > > > > ravb e6800000.ethernet ethernet: failed to switch device to config mode > > Hmm, maybe we need a larger timeout there? The current one amounts to only > ~100 ms for all cases (maybe we should parametrize the timeout?)... I don't think so because we cannot assume when RX is finished. For example, if other device sends to the hardware by using "ping -f", the hardware is operating as RX while the ping is running. > > This error means that the hardware could not change the state > > from "Operation" to "Configuration" while some tx and/or rx queue > > are operating. After that, ravb_config() in ravb_dmac_init() will fail, > > Are we seeing double messages from ravb_config()? I think we aren't... No, we are not seeing double messages from ravb_config() because ravb_stop_dma() is possible to fail before ravb_config() is called if TCCR or CSR is specific condition. > > and then any descriptors will be not allocaled anymore so that NULL > > pointer dereference happens after that on ravb_start_xmit(). > > > > To fix the issue, the ravb_tx_timeout_work() should check > > the return value of ravb_stop_dma() whether this hardware can be > > re-initialized or not. If ravb_stop_dma() fails, ravb_tx_timeout_work() > > re-enables TX and RX and just exits. > > > > [1] > > https://lore.kernel.org/linux-renesas-soc/20200518045452.2390-1-dirk.behme@xxxxxxxxxxxx/ > > > > Reported-by: Dirk Behme <dirk.behme@xxxxxxxxxxxx> > > Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx> > > Assuming the comment below is fixed: > > Reviewed-by: Sergei Shtylyov <sergei.shtylyov@xxxxxxxxx> Thanks! > > --- > > Changes from RFC v1: > > - Check the return value of ravb_stop_dma() and exit if the hardware > > condition can not be initialized in the tx timeout. > > - Update the commit subject and description. > > - Fix some typo. > > https://patchwork.kernel.org/patch/11570217/ > > > > Unfortunately, I still didn't reproduce the issue yet. So, I still > > marked RFC on this patch. > > I think the Bosch people should test this patch, as they reported the kernel oops... > > > > > drivers/net/ethernet/renesas/ravb_main.c | 14 +++++++++++++- > > 1 file changed, 13 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c > > index a442bcf6..500f5c1 100644 > > --- a/drivers/net/ethernet/renesas/ravb_main.c > > +++ b/drivers/net/ethernet/renesas/ravb_main.c > > @@ -1458,7 +1458,18 @@ static void ravb_tx_timeout_work(struct work_struct *work) > > ravb_ptp_stop(ndev); > > > > /* Wait for DMA stopping */ > > - ravb_stop_dma(ndev); > > + if (ravb_stop_dma(ndev)) { > > + /* If ravb_stop_dma() fails, the hardware is still in-progress > > + * as "Operation" mode for TX and/or RX. So, this should not > > s/in-progress as "Operation" mode/operating/. I'll fix it. > > + * call the following functions because ravb_dmac_init() is > > + * possible to fail too. Also, this should not retry > > + * ravb_stop_dma() again and again here because it's possible > > + * to wait forever. So, this just re-enables the TX and RX and > > + * skip the following re-initialization procedure. > > + */ > > + ravb_rcv_snd_enable(ndev); > > + goto out; > > + } > > > > ravb_ring_free(ndev, RAVB_BE); > > ravb_ring_free(ndev, RAVB_NC); > > @@ -1467,6 +1478,7 @@ static void ravb_tx_timeout_work(struct work_struct *work) > > ravb_dmac_init(ndev); > > BTW, that one also may fail... Yes, that's true... In this case, I think this should print error message and stop TX and RX to avoid any unexpected behaviors like kernel panic. So, I'll add such a code. Best regards, Yoshihiro Shimoda > > ravb_emac_init(ndev); > > > > +out: > > /* Initialise PTP Clock driver */ > > if (priv->chip_id == RCAR_GEN2) > > ravb_ptp_init(ndev, priv->pdev); > >
