TxSkipPatched: iso_xmit_cycle_skip.patch

ieee1394-2.6.22-14-rt-1/iso.h

@@ -123 +123 @@
-
-        /* how many times the buffer has overflowed or underflowed */
-        atomic_t overflows;
+        /* how many cycles were skipped for a given context */
+        atomic_t skips;
-
-        /* Current number of bytes lost in discarded packets */
-        int bytes_discarded;

ieee1394-2.6.22-14-rt-1/ohci1394.c

@@ -1882 +1882 @@
-        struct dma_prog_region prog;
-        struct ohci1394_iso_tasklet task;
-        int task_active;
+        int last_cycle;
+        atomic_t skips;
-
-        u32 ContextControlSet;
-        u32 ContextControlClear;
@@ -1918 +1920 @@
-        iso->hostdata = xmit;
-        xmit->ohci = iso->host->hostdata;
-        xmit->task_active = 0;
+        xmit->last_cycle = -1;
+        atomic_set(&iso->skips, 0);
-
-        dma_prog_region_init(&xmit->prog);
-
@@ -2015 +2019 @@
-                /* parse cycle */
-                cycle = le32_to_cpu(cmd->output_last.status) & 0x1FFF;
-
+                if (xmit->last_cycle > -1) {
+                        int cycle_diff = cycle - xmit->last_cycle;
+                        int skip;
+                        
+                        // unwrap
+                        if(cycle_diff < 0) {
+                                cycle_diff += 8000;
+                                if(cycle_diff < 0) {
+                                        PRINT(KERN_ERR,
+                                                "bogus cycle diff %d\n", cycle_diff);
+                                }
+                        }
+                        
+                        skip = cycle_diff - 1;
+                        if(skip > 0) {
+                                DBGMSG("skipped %d cycles without packet loss", skip);
+                                atomic_add(skip, &iso->skips);
+                        }
+                }
+                xmit->last_cycle = cycle;
+
-                /* tell the subsystem the packet has gone out */
-                hpsb_iso_packet_sent(iso, cycle, event != 0x11);
-
@@ -2102 +2127 @@
-        prev->output_last.branchAddress = cpu_to_le32(
-                dma_prog_region_offset_to_bus(&xmit->prog, sizeof(struct iso_xmit_cmd) * next_i) | 3);
-
+        /* link the skip address to this descriptor itself
+           this causes a context to skip a cycle whenever lost cycles
+           or FIFO overruns occur, without dropping the data at that point
+           the application should then decide whether this is an error condition
+           or not. Some protocols can deal with this by dropping some rate-matching
+           padding packets
+        */
+        next->output_more_immediate.branchAddress = prev->output_last.branchAddress;
+
-        /* disable interrupt, unless required by the IRQ interval */
-        if (prev_i % iso->irq_interval) {
-                prev->output_last.control &= cpu_to_le32(~(3 << 20)); /* no interrupt */

ieee1394-2.6.22-14-rt-1/raw1394.c

@@ -2507 +2507 @@
-static void raw1394_iso_fill_status(struct hpsb_iso *iso,
-                                    struct raw1394_iso_status *stat)
-{
+        int overflows = atomic_read(&iso->overflows);
+        int skips = atomic_read(&iso->skips);
-        stat->config.data_buf_size = iso->buf_size;
-        stat->config.buf_packets = iso->buf_packets;
-        stat->config.channel = iso->channel;
-        stat->config.speed = iso->speed;
-        stat->config.irq_interval = iso->irq_interval;
-        stat->n_packets = hpsb_iso_n_ready(iso);
-atomic_read(&iso->overflows
+((skips & 0xFFFF) << 16) | ((overflows & 0xFFFF)
-        stat->xmit_cycle = iso->xmit_cycle;
-}
-
@@ -2588 +2590 @@
-
-        /* reset overflow counter */
-        atomic_set(&iso->overflows, 0);
+        /* reset skip counter */
+        atomic_set(&iso->skips, 0);
-
-        return 0;
-}