From 814dae031d08d40d34c0403a54d6e659baf0ae71 Mon Sep 17 00:00:00 2001 From: Paul Fulghum Date: Tue, 22 Jul 2008 11:22:14 +0100 Subject: synclink_gt: add rx DMA buffer fill level control Add run time control for receive DMA buffer fill level to allow application to control receive latency when using stream oriented serial protocols that pass receive data to application only after a DMA buffer fills. This was previously a compile time option, but run time control is needed when application changes data rate (and latency requirements) or uses different data rates on different ports. Signed-off-by: Paul Fulghum Signed-off-by: Andrew Morton Signed-off-by: Alan Cox Signed-off-by: Linus Torvalds --- drivers/char/synclink_gt.c | 42 +++++++++++++++++++++++++++--------------- 1 file changed, 27 insertions(+), 15 deletions(-) (limited to 'drivers') diff --git a/drivers/char/synclink_gt.c b/drivers/char/synclink_gt.c index c8bc69c97d1..5ffdb364ea4 100644 --- a/drivers/char/synclink_gt.c +++ b/drivers/char/synclink_gt.c @@ -303,7 +303,7 @@ struct slgt_info { u32 idle_mode; u32 max_frame_size; /* as set by device config */ - unsigned int raw_rx_size; + unsigned int rbuf_fill_level; unsigned int if_mode; /* device status */ @@ -2676,8 +2676,29 @@ static int tx_abort(struct slgt_info *info) static int rx_enable(struct slgt_info *info, int enable) { unsigned long flags; - DBGINFO(("%s rx_enable(%d)\n", info->device_name, enable)); + unsigned int rbuf_fill_level; + DBGINFO(("%s rx_enable(%08x)\n", info->device_name, enable)); spin_lock_irqsave(&info->lock,flags); + /* + * enable[31..16] = receive DMA buffer fill level + * 0 = noop (leave fill level unchanged) + * fill level must be multiple of 4 and <= buffer size + */ + rbuf_fill_level = ((unsigned int)enable) >> 16; + if (rbuf_fill_level) { + if ((rbuf_fill_level > DMABUFSIZE) || (rbuf_fill_level % 4)) + return -EINVAL; + info->rbuf_fill_level = rbuf_fill_level; + rx_stop(info); /* restart receiver to use new fill level */ + } + + /* + * enable[1..0] = receiver enable command + * 0 = disable + * 1 = enable + * 2 = enable or force hunt mode if already enabled + */ + enable &= 3; if (enable) { if (!info->rx_enabled) rx_start(info); @@ -3444,7 +3465,7 @@ static struct slgt_info *alloc_dev(int adapter_num, int port_num, struct pci_dev info->magic = MGSL_MAGIC; INIT_WORK(&info->task, bh_handler); info->max_frame_size = 4096; - info->raw_rx_size = DMABUFSIZE; + info->rbuf_fill_level = DMABUFSIZE; info->port.close_delay = 5*HZ/10; info->port.closing_wait = 30*HZ; init_waitqueue_head(&info->status_event_wait_q); @@ -4447,16 +4468,7 @@ static void free_rbufs(struct slgt_info *info, unsigned int i, unsigned int last while(!done) { /* reset current buffer for reuse */ info->rbufs[i].status = 0; - switch(info->params.mode) { - case MGSL_MODE_RAW: - case MGSL_MODE_MONOSYNC: - case MGSL_MODE_BISYNC: - set_desc_count(info->rbufs[i], info->raw_rx_size); - break; - default: - set_desc_count(info->rbufs[i], DMABUFSIZE); - } - + set_desc_count(info->rbufs[i], info->rbuf_fill_level); if (i == last) done = 1; if (++i == info->rbuf_count) @@ -4563,7 +4575,7 @@ check_again: DBGBH(("%s rx frame status=%04X size=%d\n", info->device_name, status, framesize)); - DBGDATA(info, info->rbufs[start].buf, min_t(int, framesize, DMABUFSIZE), "rx"); + DBGDATA(info, info->rbufs[start].buf, min_t(int, framesize, info->rbuf_fill_level), "rx"); if (framesize) { if (!(info->params.crc_type & HDLC_CRC_RETURN_EX)) { @@ -4583,7 +4595,7 @@ check_again: info->icount.rxok++; while(copy_count) { - int partial_count = min(copy_count, DMABUFSIZE); + int partial_count = min_t(int, copy_count, info->rbuf_fill_level); memcpy(p, info->rbufs[i].buf, partial_count); p += partial_count; copy_count -= partial_count; -- cgit v1.2.3