[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>

1 files changed, 43 insertions, 10 deletions

diff --git a/drivers/media/video/gspca/xirlink_cit.c b/drivers/media/video/gspca/xirlink_cit.c
index 8715577bc2d8..daeda2cd9d09 100644
--- 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,