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Date: Fri, 30 Oct 2020 13:43:51 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Loic Poulain <loic.poulain@...aro.org>
Cc: kuba@...nel.org, davem@...emloft.net, hemantk@...eaurora.org,
netdev@...r.kernel.org, linux-arm-msm@...r.kernel.org,
bbhatt@...eaurora.org, willemdebruijn.kernel@...il.com,
jhugo@...eaurora.org
Subject: Re: [PATCH v8 2/2] net: Add mhi-net driver
Hi Loic,
On Wed, Oct 28, 2020 at 05:34:58PM +0100, Loic Poulain wrote:
> This patch adds a new network driver implementing MHI transport for
> network packets. Packets can be in any format, though QMAP (rmnet)
> is the usual protocol (flow control + PDN mux).
>
> It support two MHI devices, IP_HW0 which is, the path to the IPA
> (IP accelerator) on qcom modem, And IP_SW0 which is the software
> driven IP path (to modem CPU).
>
This patch looks good to me. I just commented few nits inline. With those
addressed, you can have my:
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Thanks,
Mani
> Signed-off-by: Loic Poulain <loic.poulain@...aro.org>
> ---
> v2: - rebase on net-next
> - remove useless skb_linearize
> - check error type on mhi_queue return
> - rate limited errors
> - Schedule RX refill only on 'low' buf level
> - SET_NETDEV_DEV in probe
> - reorder device remove sequence
> v3: - Stop channels on net_register error
> - Remove useles parentheses
> - Add driver .owner
> v4: - prevent potential cpu hog in rx-refill loop
> - Access mtu via READ_ONCE
> v5: - Fix access to u64 stats
> v6: - Stop TX queue earlier if queue is full
> - Preventing 'abnormal' NETDEV_TX_BUSY path
> v7: - Stop dl/ul cb operations on channel resetting
> v8: - remove premature comment about TX threading gain
> - check rx_queued to determine queuing limits
> - fix probe error path (unified goto usage)
>
> drivers/net/Kconfig | 7 ++
> drivers/net/Makefile | 1 +
> drivers/net/mhi_net.c | 313 ++++++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 321 insertions(+)
> create mode 100644 drivers/net/mhi_net.c
>
> diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
> index 1368d1d..11a6357 100644
> --- a/drivers/net/Kconfig
> +++ b/drivers/net/Kconfig
> @@ -426,6 +426,13 @@ config VSOCKMON
> mostly intended for developers or support to debug vsock issues. If
> unsure, say N.
>
> +config MHI_NET
> + tristate "MHI network driver"
> + depends on MHI_BUS
> + help
> + This is the network driver for MHI. It can be used with
network driver for MHI bus.
> + QCOM based WWAN modems (like SDX55). Say Y or M.
> +
> endif # NET_CORE
>
> config SUNGEM_PHY
> diff --git a/drivers/net/Makefile b/drivers/net/Makefile
> index 94b6080..8312037 100644
> --- a/drivers/net/Makefile
> +++ b/drivers/net/Makefile
> @@ -34,6 +34,7 @@ obj-$(CONFIG_GTP) += gtp.o
> obj-$(CONFIG_NLMON) += nlmon.o
> obj-$(CONFIG_NET_VRF) += vrf.o
> obj-$(CONFIG_VSOCKMON) += vsockmon.o
> +obj-$(CONFIG_MHI_NET) += mhi_net.o
>
> #
> # Networking Drivers
> diff --git a/drivers/net/mhi_net.c b/drivers/net/mhi_net.c
> new file mode 100644
> index 0000000..4ba146d
> --- /dev/null
> +++ b/drivers/net/mhi_net.c
> @@ -0,0 +1,313 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/* MHI Network driver - Network over MHI
Network over MHI bus.
> + *
> + * Copyright (C) 2020 Linaro Ltd <loic.poulain@...aro.org>
> + */
> +
> +#include <linux/if_arp.h>
> +#include <linux/mhi.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/module.h>
> +#include <linux/netdevice.h>
> +#include <linux/skbuff.h>
> +#include <linux/u64_stats_sync.h>
> +
> +#define MIN_MTU ETH_MIN_MTU
> +#define MAX_MTU 0xffff
> +#define DEFAULT_MTU 16384
Please add a prefix to avoid namespace issues in future...
> +
> +struct mhi_net_stats {
> + u64_stats_t rx_packets;
> + u64_stats_t rx_bytes;
> + u64_stats_t rx_errors;
> + u64_stats_t rx_dropped;
> + u64_stats_t tx_packets;
> + u64_stats_t tx_bytes;
> + u64_stats_t tx_errors;
> + u64_stats_t tx_dropped;
> + atomic_t rx_queued;
> + struct u64_stats_sync tx_syncp;
> + struct u64_stats_sync rx_syncp;
> +};
> +
> +struct mhi_net_dev {
> + struct mhi_device *mdev;
> + struct net_device *ndev;
> + struct delayed_work rx_refill;
> + struct mhi_net_stats stats;
> + u32 rx_queue_sz;
> +};
> +
[...]
> +static void mhi_net_rx_refill_work(struct work_struct *work)
> +{
> + struct mhi_net_dev *mhi_netdev = container_of(work, struct mhi_net_dev,
> + rx_refill.work);
> + struct net_device *ndev = mhi_netdev->ndev;
> + struct mhi_device *mdev = mhi_netdev->mdev;
> + int size = READ_ONCE(ndev->mtu);
> + struct sk_buff *skb;
> + int err;
> +
> + do {
> + skb = netdev_alloc_skb(ndev, size);
> + if (unlikely(!skb))
> + break;
> +
> + err = mhi_queue_skb(mdev, DMA_FROM_DEVICE, skb, size, MHI_EOT);
> + if (unlikely(err)) {
> + net_err_ratelimited("%s: Failed to queue RX buf (%d)\n",
> + ndev->name, err);
> + kfree_skb(skb);
> + break;
> + }
> +
> + /* Do not hog the CPU if rx buffers are completed faster than
> + * queued (unlikely).
s/completed/consumed
> + */
> + cond_resched();
> + } while (atomic_inc_return(&mhi_netdev->stats.rx_queued) < mhi_netdev->rx_queue_sz);
> +
> + /* If we're still starved of rx buffers, reschedule later */
> + if (unlikely(!atomic_read(&mhi_netdev->stats.rx_queued)))
> + schedule_delayed_work(&mhi_netdev->rx_refill, HZ / 2);
> +}
> +
> +static int mhi_net_probe(struct mhi_device *mhi_dev,
> + const struct mhi_device_id *id)
> +{
> + const char *netname = (char *)id->driver_data;
> + struct mhi_net_dev *mhi_netdev;
> + struct net_device *ndev;
> + struct device *dev = &mhi_dev->dev;
> + int err;
Since this is a networking driver, please stick to reverse xmas tree order for
local variables.
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