| Message ID | 20220610094517.1298261-1-o.rempel@pengutronix.de (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net-next,v1,1/1] net: macb: fix negative max_mtu size for sama5d3 | expand |
On 10.06.2022 12:45, Oleksij Rempel wrote: > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe > > On Microchip SAMA5D3 the JML will return null. Should be because it hasn't been configured yet. It is configured later on macb_init_hw() which is called on open. So, after header and FCS length > subtraction we will get negative max_mtu size. This issue was directly > affecting DSA drivers with MTU support (for example KSZ9477). > > Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de> > --- > drivers/net/ethernet/cadence/macb_main.c | 20 +++++++++++++++++--- > 1 file changed, 17 insertions(+), 3 deletions(-) > > diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c > index d89098f4ede8..c7e1c9ac9809 100644 > --- a/drivers/net/ethernet/cadence/macb_main.c > +++ b/drivers/net/ethernet/cadence/macb_main.c > @@ -4913,10 +4913,24 @@ static int macb_probe(struct platform_device *pdev) > > /* MTU range: 68 - 1500 or 10240 */ > dev->min_mtu = GEM_MTU_MIN_SIZE; > - if (bp->caps & MACB_CAPS_JUMBO) > - dev->max_mtu = gem_readl(bp, JML) - ETH_HLEN - ETH_FCS_LEN; > - else > + if (bp->caps & MACB_CAPS_JUMBO) { > + u32 val; > + > + if (bp->jumbo_max_len) > + val = bp->jumbo_max_len; > + else > + val = gem_readl(bp, JML); > + > + if (val < ETH_DATA_LEN) { > + dev_warn(&pdev->dev, "Suspicious max MTU size (%u), overwriting to %u\n", > + val, ETH_DATA_LEN); > + dev->max_mtu = ETH_DATA_LEN; > + } else { > + dev->max_mtu = val - ETH_HLEN - ETH_FCS_LEN; > + } > + } else { Maybe, simply would be to also check bp->jumbo_max_len and have something like: if ((bp->caps & MACB_CAPS_JUMBO) && bp->jumbo_max_len) dev->max_mtu = bp->jumbo_max_len - ETH_HLEN - ETH_FCS_LEN; if that works as it is the same condition used when updating JML in macb_init_hw(). Thank you, Claudiu Beznea > dev->max_mtu = ETH_DATA_LEN; > + } > > if (bp->caps & MACB_CAPS_BD_RD_PREFETCH) { > val = GEM_BFEXT(RXBD_RDBUFF, gem_readl(bp, DCFG10)); > -- > 2.30.2 >
diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c index d89098f4ede8..c7e1c9ac9809 100644 --- a/drivers/net/ethernet/cadence/macb_main.c +++ b/drivers/net/ethernet/cadence/macb_main.c @@ -4913,10 +4913,24 @@ static int macb_probe(struct platform_device *pdev) /* MTU range: 68 - 1500 or 10240 */ dev->min_mtu = GEM_MTU_MIN_SIZE; - if (bp->caps & MACB_CAPS_JUMBO) - dev->max_mtu = gem_readl(bp, JML) - ETH_HLEN - ETH_FCS_LEN; - else + if (bp->caps & MACB_CAPS_JUMBO) { + u32 val; + + if (bp->jumbo_max_len) + val = bp->jumbo_max_len; + else + val = gem_readl(bp, JML); + + if (val < ETH_DATA_LEN) { + dev_warn(&pdev->dev, "Suspicious max MTU size (%u), overwriting to %u\n", + val, ETH_DATA_LEN); + dev->max_mtu = ETH_DATA_LEN; + } else { + dev->max_mtu = val - ETH_HLEN - ETH_FCS_LEN; + } + } else { dev->max_mtu = ETH_DATA_LEN; + } if (bp->caps & MACB_CAPS_BD_RD_PREFETCH) { val = GEM_BFEXT(RXBD_RDBUFF, gem_readl(bp, DCFG10));
On Microchip SAMA5D3 the JML will return null. So, after header and FCS length subtraction we will get negative max_mtu size. This issue was directly affecting DSA drivers with MTU support (for example KSZ9477). Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de> --- drivers/net/ethernet/cadence/macb_main.c | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-)