[media] gspca_xirlink_cit: various usb bandwidth allocation improvements / fixes

The following usb bandwidth allocation changes were made to the ibm netcam
pro code:
- Don't restart negotiation at max packet size on stop0, as that gets called
  by gspca_main during negotiation. Move this to sd_isoc_init.
- Don't ask for full bandwidth when running at 160x120, that does not need
  full bandwidth
- Make minimum acceptable bandwidth depend upon resolution

[mchehab@redhat.com: Fix CodingStyle problems at switch statements]
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

diff --git a/drivers/media/video/gspca/xirlink_cit.c b/drivers/media/video/gspca/xirlink_cit.c
index 8715577..daeda2c 100644 (file)
--- a/drivers/media/video/gspca/xirlink_cit.c
+++ b/drivers/media/video/gspca/xirlink_cit.c
@@ -2769,16 +2769,55 @@ static int sd_start(struct gspca_dev *gspca_dev)
        return 0;
 }
 
+static int sd_isoc_init(struct gspca_dev *gspca_dev)
+{
+       struct usb_host_interface *alt;
+       int max_packet_size;
+
+       switch (gspca_dev->width) {
+       case 160:
+               max_packet_size = 450;
+               break;
+       case 176:
+               max_packet_size = 600;
+               break;
+       default:
+               max_packet_size = 1022;
+               break;
+       }
+
+       /* Start isoc bandwidth "negotiation" at max isoc bandwidth */
+       alt = &gspca_dev->dev->config->intf_cache[0]->altsetting[1];
+       alt->endpoint[0].desc.wMaxPacketSize = cpu_to_le16(max_packet_size);
+
+       return 0;
+}
+
 static int sd_isoc_nego(struct gspca_dev *gspca_dev)
 {
-       int ret, packet_size;
+       int ret, packet_size, min_packet_size;
        struct usb_host_interface *alt;
 
+       switch (gspca_dev->width) {
+       case 160:
+               min_packet_size = 200;
+               break;
+       case 176:
+               min_packet_size = 266;
+               break;
+       default:
+               min_packet_size = 400;
+               break;
+       }
+
        alt = &gspca_dev->dev->config->intf_cache[0]->altsetting[1];
        packet_size = le16_to_cpu(alt->endpoint[0].desc.wMaxPacketSize);
-       packet_size -= 100;
-       if (packet_size < 300)
+       if (packet_size <= min_packet_size)
                return -EIO;
+
+       packet_size -= 100;
+       if (packet_size < min_packet_size)
+               packet_size = min_packet_size;
        alt->endpoint[0].desc.wMaxPacketSize = cpu_to_le16(packet_size);
 
        ret = usb_set_interface(gspca_dev->dev, gspca_dev->iface, 1);
@@ -2796,15 +2835,12 @@ static void sd_stopN(struct gspca_dev *gspca_dev)
 static void sd_stop0(struct gspca_dev *gspca_dev)
 {
        struct sd *sd = (struct sd *) gspca_dev;
-       struct usb_host_interface *alt;
 
        /* We cannot use gspca_dev->present here as that is not set when
           sd_init gets called and we get called from sd_init */
        if (!gspca_dev->dev)
                return;
 
-       alt = &gspca_dev->dev->config->intf_cache[0]->altsetting[1];
-
        switch (sd->model) {
        case CIT_MODEL0:
                /* HDG windows does this, but it causes the cams autogain to
@@ -2859,10 +2895,6 @@ static void sd_stop0(struct gspca_dev *gspca_dev)
                   restarting the stream after this */
                /* cit_write_reg(gspca_dev, 0x0000, 0x0112); */
                cit_write_reg(gspca_dev, 0x00c0, 0x0100);
-
-               /* Start isoc bandwidth "negotiation" at max isoc bandwith
-                  next stream start */
-               alt->endpoint[0].desc.wMaxPacketSize = cpu_to_le16(1022);
                break;
        }
 }
@@ -3179,6 +3211,7 @@ static const struct sd_desc sd_desc_isoc_nego = {
        .config = sd_config,
        .init = sd_init,
        .start = sd_start,
+       .isoc_init = sd_isoc_init,
        .isoc_nego = sd_isoc_nego,
        .stopN = sd_stopN,
        .stop0 = sd_stop0,