Re: [PATCH V2] can: usb: f81604: add Fintek F81604 support

[Peter Hong <peter_hong@xxxxxxxxxxxxx>]

Hi Vincent,

Vincent MAILHOL 於 2023/3/21 下午 11:50 寫道:
> > +static netdev_tx_t f81604_start_xmit(struct sk_buff *skb,
> > +                                    struct net_device *netdev)
> > +{
> > +       struct can_frame *cf = (struct can_frame *)skb->data;
> > +       struct f81604_port_priv *priv = netdev_priv(netdev);
> > +       struct net_device_stats *stats = &netdev->stats;
> > +       int status;
> > +       u8 *ptr;
> > +       u32 id;
> > +
> > +       if (can_dropped_invalid_skb(netdev, skb))
> > +               return NETDEV_TX_OK;
> > +
> > +       netif_stop_queue(netdev);
> > +
> > +       ptr = priv->bulk_write_buffer;
> > +       memset(ptr, 0, F81604_DATA_SIZE);
> > +
> > +       ptr[0] = F81604_CMD_DATA;
> > +       ptr[1] = min_t(u8, cf->can_dlc & 0xf, 8);
> > +
> > +       if (cf->can_id & CAN_EFF_FLAG) {
> > +               id = (cf->can_id & CAN_ERR_MASK) << 3;
> > +               ptr[1] |= F81604_EFF_BIT;
> > +               ptr[2] = (id >> 24) & 0xff;
> > +               ptr[3] = (id >> 16) & 0xff;
> > +               ptr[4] = (id >> 8) & 0xff;
> > +               ptr[5] = (id >> 0) & 0xff;
> > +               memcpy(&ptr[6], cf->data, ptr[1]);
> Rather than manipulating an opaque u8 array, please declare a
> structure with explicit names.

I had try to declare a struct like below and refactoring code :

struct f81604_bulk_data {
    u8 cmd;
    u8 dlc;

    union {
        struct {
            u8 id1, id2;
            u8 data[CAN_MAX_DLEN];
        } sff;

        struct {
            u8 id1, id2, id3, id4;
            u8 data[CAN_MAX_DLEN];
        } eff;
    };
} __attribute__((packed));

This struct can used in TX/RX bulk in/out. Is it ok?

> +static int f81604_prepare_urbs(struct net_device *netdev)
> +{
> +       static const u8 bulk_in_addr[F81604_MAX_DEV] = { 0x82, 0x84 };
> +       static const u8 bulk_out_addr[F81604_MAX_DEV] = { 0x01, 0x03 };
> +       static const u8 int_in_addr[F81604_MAX_DEV] = { 0x81, 0x83 };
> +       struct f81604_port_priv *priv = netdev_priv(netdev);
> +       int id = netdev->dev_id;
> +       int i;
> +
> +       /* initialize to NULL for error recovery */
> +       for (i = 0; i < F81604_MAX_RX_URBS; ++i)
> +               priv->read_urb[i] = NULL;
> priv was allocated with devm_kzalloc() so it should already be zeroed,
> right? What is the purpose of this loop?

This operation due to following condition:
    f81604_open() -> f81604_close() -> f81604_open() failed.

We had used  devm_kzalloc() in f81604_probe(), so first f81604_open() all
pointers are NULL. But after f81604_close() then f81604_open() second
times, the URB pointers are not NULLed, it'll makes error on 2nd 
f81604_open()
with fail.

> > +/* Called by the usb core when driver is unloaded or device is removed */
> > +static void f81604_disconnect(struct usb_interface *intf)
> > +{
> > +       struct f81604_priv *priv = usb_get_intfdata(intf);
> > +       int i;
> > +
> > +       for (i = 0; i < F81604_MAX_DEV; ++i) {
> > +               if (!priv->netdev[i])
> > +                       continue;
> > +
> > +               unregister_netdev(priv->netdev[i]);
> > +               free_candev(priv->netdev[i]);
> > +       }
>   i> +}

Is typo here?

Thanks.