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Date: Tue, 14 Jun 2011 10:49:39 +0200
From: Oliver Neukum <oneukum@...e.de>
To: "Marius B. Kotsbak" <marius.kotsbak@...il.com>
Cc: davem@...emloft.net, netdev@...r.kernel.org,
linux-usb@...r.kernel.org, "Marius B. Kotsbak" <marius@...sbak.com>
Subject: Re: [PATCH] net/usb: Add Samsung Kalmia driver for Samsung GT-B3730
Am Samstag, 11. Juni 2011, 23:55:18 schrieb Marius B. Kotsbak:
Hi,
thanks for writing a new driver. My comments are included in the quote.
Regards
Oliver
> +static int
> +kalmia_init_and_get_ethernet_addr(struct usbnet *dev, u8 *ethernet_addr)
> +{
> + char init_msg_1[] =
> + { 0x57, 0x50, 0x04, 0x00, 0x00, 0x00, 0x00, 0x20, 0x00, 0x00,
> + 0x00, 0x00 };
> + char init_msg_2[] =
> + { 0x57, 0x50, 0x04, 0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0xf4,
> + 0x00, 0x00 };
> + char receive_buf[28];
You are doing DMA on the stack. This will fail on some architectures.
> + int status;
> +
> + status = kalmia_send_init_packet(dev, init_msg_1, sizeof(init_msg_1)
> + / sizeof(init_msg_1[0]), receive_buf, 24);
> + if (status != 0)
> + return status;
> +
> + status = kalmia_send_init_packet(dev, init_msg_2, sizeof(init_msg_2)
> + / sizeof(init_msg_2[0]), receive_buf, 28);
> + if (status != 0)
> + return status;
> +
> + memcpy(ethernet_addr, receive_buf + 10, ETH_ALEN);
> +
> + return status;
> +}
> +
> +static int
> +kalmia_bind(struct usbnet *dev, struct usb_interface *intf)
> +{
> + u8 status;
> + u8 ethernet_addr[ETH_ALEN];
> +
> + /* Don't bind to AT command interface */
> + if (intf->cur_altsetting->desc.bInterfaceClass != USB_CLASS_VENDOR_SPEC)
> + return -EINVAL;
> +
> + dev->in = usb_rcvbulkpipe(dev->udev, 0x81 & USB_ENDPOINT_NUMBER_MASK);
> + dev->out = usb_sndbulkpipe(dev->udev, 0x02 & USB_ENDPOINT_NUMBER_MASK);
> + dev->status = NULL;
> +
> + dev->net->hard_header_len += KALMIA_HEADER_LENGTH;
> + dev->hard_mtu = 1400;
> + dev->rx_urb_size = dev->hard_mtu * 10; // Found as optimal after testing
> +
> + status = kalmia_init_and_get_ethernet_addr(dev, ethernet_addr);
> +
> + if (status < 0) {
> + usb_set_intfdata(intf, NULL);
> + usb_driver_release_interface(driver_of(intf), intf);
> + return status;
Why are you doing this? What is to be undone?
> + }
> +
> + memcpy(dev->net->dev_addr, ethernet_addr, ETH_ALEN);
> + memcpy(dev->net->perm_addr, ethernet_addr, ETH_ALEN);
> +
> + return status;
> +}
> +
> +static struct sk_buff *
> +kalmia_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags)
> +{
> + struct sk_buff *skb2 = NULL;
> + u16 content_len;
> + unsigned char *header_start;
> + unsigned char ether_type_1, ether_type_2;
> + u8 remainder, padlen = 0;
> +
> + if (!skb_cloned(skb)) {
> + int headroom = skb_headroom(skb);
> + int tailroom = skb_tailroom(skb);
> +
> + if ((tailroom >= KALMIA_ALIGN_SIZE) && (headroom
> + >= KALMIA_HEADER_LENGTH))
> + goto done;
> +
> + if ((headroom + tailroom) > (KALMIA_HEADER_LENGTH
> + + KALMIA_ALIGN_SIZE)) {
> + skb->data = memmove(skb->head + KALMIA_HEADER_LENGTH,
> + skb->data, skb->len);
> + skb_set_tail_pointer(skb, skb->len);
> + goto done;
> + }
> + }
> +
> + skb2 = skb_copy_expand(skb, KALMIA_HEADER_LENGTH,
> + KALMIA_ALIGN_SIZE, flags);
> + if (!skb2)
> + return NULL;
> +
> + dev_kfree_skb_any(skb);
> + skb = skb2;
> +
> + done: header_start = skb_push(skb, KALMIA_HEADER_LENGTH);
coding style
> + ether_type_1 = header_start[KALMIA_HEADER_LENGTH + 12];
> + ether_type_2 = header_start[KALMIA_HEADER_LENGTH + 13];
> +
> + netdev_dbg(dev->net, "Sending etherType: %02x%02x", ether_type_1,
> + ether_type_2);
> +
> + /* According to empiric data for data packages */
> + header_start[0] = 0x57;
> + header_start[1] = 0x44;
> + content_len = skb->len - KALMIA_HEADER_LENGTH;
> + header_start[2] = (content_len & 0xff); /* low byte */
> + header_start[3] = (content_len >> 8); /* high byte */
Please use an endianness macro
> + header_start[4] = ether_type_1;
> + header_start[5] = ether_type_2;
> +
> + /* Align to 4 bytes by padding with zeros */
> + remainder = skb->len % KALMIA_ALIGN_SIZE;
> + if (remainder > 0) {
> + padlen = KALMIA_ALIGN_SIZE - remainder;
> + memset(skb_put(skb, padlen), 0, padlen);
> + }
> +
> + netdev_dbg(
> + dev->net,
> + "Sending package with length %i and padding %i. Header: %02x:%02x:%02x:%02x:%02x:%02x.",
> + content_len, padlen, header_start[0], header_start[1],
> + header_start[2], header_start[3], header_start[4],
> + header_start[5]);
> +
> + return skb;
> +}
> +
> +static int
> +kalmia_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
> +{
> + /*
> + * Our task here is to strip off framing, leaving skb with one
> + * data frame for the usbnet framework code to process.
> + */
> + const u8 HEADER_END_OF_USB_PACKET[] =
> + { 0x57, 0x5a, 0x00, 0x00, 0x08, 0x00 };
> + const u8 EXPECTED_UNKNOWN_HEADER_1[] =
> + { 0x57, 0x43, 0x1e, 0x00, 0x15, 0x02 };
> + const u8 EXPECTED_UNKNOWN_HEADER_2[] =
> + { 0x57, 0x50, 0x0e, 0x00, 0x00, 0x00 };
What does the compiler do to this declaration?
> + u8 i = 0;
Why not int?
> +
> + /* incomplete header? */
> + if (skb->len < KALMIA_HEADER_LENGTH)
> + return 0;
> +
> + do {
> + struct sk_buff *skb2 = NULL;
> + u8 *header_start;
> + u16 usb_packet_length, ether_packet_length;
> + int is_last;
> +
> + header_start = skb->data;
> +
> + if (unlikely(header_start[0] != 0x57 || header_start[1] != 0x44)) {
> + if (!memcmp(header_start, EXPECTED_UNKNOWN_HEADER_1,
> + sizeof(EXPECTED_UNKNOWN_HEADER_1)) || !memcmp(
> + header_start, EXPECTED_UNKNOWN_HEADER_2,
> + sizeof(EXPECTED_UNKNOWN_HEADER_2))) {
> + netdev_dbg(
> + dev->net,
> + "Received expected unknown frame header: %02x:%02x:%02x:%02x:%02x:%02x. Package length: %i\n",
> + header_start[0], header_start[1],
> + header_start[2], header_start[3],
> + header_start[4], header_start[5],
> + skb->len - KALMIA_HEADER_LENGTH);
> + }
> + else {
> + netdev_err(
> + dev->net,
> + "Received unknown frame header: %02x:%02x:%02x:%02x:%02x:%02x. Package length: %i\n",
> + header_start[0], header_start[1],
> + header_start[2], header_start[3],
> + header_start[4], header_start[5],
> + skb->len - KALMIA_HEADER_LENGTH);
> + return 0;
> + }
> + }
> + else
> + netdev_dbg(
> + dev->net,
> + "Received header: %02x:%02x:%02x:%02x:%02x:%02x. Package length: %i\n",
> + header_start[0], header_start[1], header_start[2],
> + header_start[3], header_start[4], header_start[5],
> + skb->len - KALMIA_HEADER_LENGTH);
> +
> + /* subtract start header and end header */
> + usb_packet_length = skb->len - (2 * KALMIA_HEADER_LENGTH);
> + ether_packet_length = header_start[2] + (header_start[3] << 8);
Please use an endianness macro
> + skb_pull(skb, KALMIA_HEADER_LENGTH);
> +
> + /* Some small packets misses end marker */
> + if (usb_packet_length < ether_packet_length) {
> + ether_packet_length = usb_packet_length
> + + KALMIA_HEADER_LENGTH;
> + is_last = true;
> + }
> + else {
> + netdev_dbg(dev->net, "Correct package length #%i", i
> + + 1);
> +
> + is_last = (memcmp(skb->data + ether_packet_length,
> + HEADER_END_OF_USB_PACKET,
> + sizeof(HEADER_END_OF_USB_PACKET)) == 0);
> + if (!is_last) {
> + header_start = skb->data + ether_packet_length;
> + netdev_dbg(
> + dev->net,
> + "End header: %02x:%02x:%02x:%02x:%02x:%02x. Package length: %i\n",
> + header_start[0], header_start[1],
> + header_start[2], header_start[3],
> + header_start[4], header_start[5],
> + skb->len - KALMIA_HEADER_LENGTH);
> + }
> + }
> +
> + if (is_last) {
> + skb2 = skb;
> + }
> + else {
> + skb2 = skb_clone(skb, GFP_ATOMIC);
> + if (unlikely(!skb2))
> + return 0;
> + }
> +
> + skb_trim(skb2, ether_packet_length);
> +
> + if (is_last) {
> + return 1;
> + }
> + else {
> + usbnet_skb_return(dev, skb2);
> + skb_pull(skb, ether_packet_length);
> + }
> +
> + i++;
> + }
> + while (skb->len);
> +
> + return 1;
> +}
> +
> +static const struct driver_info kalmia_info = {
> + .description = "Samsung Kalmia LTE USB dongle",
> + .flags = FLAG_WWAN,
> + .bind = kalmia_bind,
> + .rx_fixup = kalmia_rx_fixup,
> + .tx_fixup = kalmia_tx_fixup
> +};
> +
> +/*-------------------------------------------------------------------------*/
> +
> +static const struct usb_device_id products[] = {
> + /* The unswitched USB ID, to get the module auto loaded: */
> + { USB_DEVICE(0x04e8, 0x689a) },
Why is this needed? Doesn't the switch trigger an autoload?
> + /* The stick swithed into modem (by e.g. usb_modeswitch): */
> + { USB_DEVICE(0x04e8, 0x6889),
> + .driver_info = (unsigned long) &kalmia_info, },
> + { /* EMPTY == end of list */} };
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