| Message ID | 1616510707-27210-2-git-send-email-loic.poulain@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | [RESEND,net-next,1/2] net: mhi: Allow decoupled MTU/MRU | expand |
On Tue, 23 Mar 2021 15:45:07 +0100 Loic Poulain wrote: > MBIM protocol makes the interface asymmetric, ingress data received > from MHI is MBIM protocol, that can contain multiple aggregated IP > packets, while egress data received from network stack is IP protocol. > > Set a default MTU to 1500 (usual network MTU for WWAN), and MRU to 32K > which is the default size of MBIM-over-MHI packets. > > Signed-off-by: Loic Poulain <loic.poulain@linaro.org> > --- > drivers/net/mhi/proto_mbim.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/drivers/net/mhi/proto_mbim.c b/drivers/net/mhi/proto_mbim.c > index 75b5484..29d8577 100644 > --- a/drivers/net/mhi/proto_mbim.c > +++ b/drivers/net/mhi/proto_mbim.c > @@ -26,6 +26,9 @@ > > #define MBIM_NDP16_SIGN_MASK 0x00ffffff > > +#define MHI_MBIM_DEFAULT_MRU 32768 > +#define MHI_MBIM_DEFAULT_MTU 1500 > + > struct mbim_context { > u16 rx_seq; > u16 tx_seq; > @@ -282,6 +285,8 @@ static int mbim_init(struct mhi_net_dev *mhi_netdev) > return -ENOMEM; > > ndev->needed_headroom = sizeof(struct mbim_tx_hdr); > + ndev->mtu = MHI_MBIM_DEFAULT_MTU; > + mhi_netdev->mru = MHI_MBIM_DEFAULT_MRU; > > return 0; > } 32k + skb overhead will result in rather large contiguous allocation. Using ~3.5k buffers (basically a page - paddings and skb_shinfo) should be much more resilient, and still very efficient. This sort of 32k buffer thing is common for USB, but I thought MHI is over PCI so there should be no bus considerations once we're above 1k.
diff --git a/drivers/net/mhi/proto_mbim.c b/drivers/net/mhi/proto_mbim.c index 75b5484..29d8577 100644 --- a/drivers/net/mhi/proto_mbim.c +++ b/drivers/net/mhi/proto_mbim.c @@ -26,6 +26,9 @@ #define MBIM_NDP16_SIGN_MASK 0x00ffffff +#define MHI_MBIM_DEFAULT_MRU 32768 +#define MHI_MBIM_DEFAULT_MTU 1500 + struct mbim_context { u16 rx_seq; u16 tx_seq; @@ -282,6 +285,8 @@ static int mbim_init(struct mhi_net_dev *mhi_netdev) return -ENOMEM; ndev->needed_headroom = sizeof(struct mbim_tx_hdr); + ndev->mtu = MHI_MBIM_DEFAULT_MTU; + mhi_netdev->mru = MHI_MBIM_DEFAULT_MRU; return 0; }
MBIM protocol makes the interface asymmetric, ingress data received from MHI is MBIM protocol, that can contain multiple aggregated IP packets, while egress data received from network stack is IP protocol. Set a default MTU to 1500 (usual network MTU for WWAN), and MRU to 32K which is the default size of MBIM-over-MHI packets. Signed-off-by: Loic Poulain <loic.poulain@linaro.org> --- drivers/net/mhi/proto_mbim.c | 5 +++++ 1 file changed, 5 insertions(+) -- 2.7.4