The patch titled
powerpc/cell spidernet low watermark
has been removed from the -mm tree. Its filename is
powerpc-cell-spidernet-low-watermark-patch.patch
This patch was dropped because it is obsolete
------------------------------------------------------
Subject: powerpc/cell spidernet low watermark
From: Linas Vepstas <linas@xxxxxxxxxxxxxx>
Implement basic low-watermark support for the transmit queue. Hardware
low-watermarks allow a properly configured kernel to continously stream data
to a device and not have to handle any interrupts at all in doing so. Correct
zero-interrupt operation can be actually observed for this driver, when the
socket buffer is made large enough.
The basic idea of a low-watermark interrupt is as follows. The device driver
queues up a bunch of packets for the hardware to transmit, and then kicks the
hardware to get it started. As the hardware drains the queue of pending,
untransmitted packets, the device driver will want to know when the queue is
almost empty, so that it can queue some more packets.
If the queue drains down to the low waterark, then an interrupt will be
generated. However, if the kernel/driver continues to add enough packets to
keep the queue partially filled, no interrupt will actually be generated, and
the hardware can continue streaming packets indefinitely in this mode.
The implementation is done by setting the DESCR_TXDESFLG flag in one of the
packets. When the hardware sees this flag, it will interrupt the device
driver. Because this flag is on a fixed packet, rather than at fixed location
in the queue, the code below needs to move the flag as more packets are queued
up. This implementation attempts to keep the flag at about 1/4 from "empty".
Signed-off-by: Linas Vepstas <linas@xxxxxxxxxxxxxx>
Signed-off-by: James K Lewis <jklewis@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
drivers/net/spider_net.c | 56 +++++++++++++++++++++++++++++++++----
drivers/net/spider_net.h | 6 ++-
2 files changed, 55 insertions(+), 7 deletions(-)
diff -puN drivers/net/spider_net.c~powerpc-cell-spidernet-low-watermark-patch drivers/net/spider_net.c
--- a/drivers/net/spider_net.c~powerpc-cell-spidernet-low-watermark-patch
+++ a/drivers/net/spider_net.c
@@ -703,6 +703,39 @@ spider_net_release_tx_descr(struct spide
dev_kfree_skb_any(skb);
}
+static void
+spider_net_set_low_watermark(struct spider_net_card *card)
+{
+ int status;
+ int cnt=0;
+ int i;
+ struct spider_net_descr *descr = card->tx_chain.tail;
+
+ /* Measure the length of the queue. */
+ while (descr != card->tx_chain.head) {
+ status = descr->dmac_cmd_status & SPIDER_NET_DESCR_NOT_IN_USE;
+ if (status == SPIDER_NET_DESCR_NOT_IN_USE)
+ break;
+ descr = descr->next;
+ cnt++;
+ }
+ if (cnt == 0)
+ return;
+
+ /* Set low-watermark 3/4th's of the way into the queue. */
+ descr = card->tx_chain.tail;
+ cnt = (cnt*3)/4;
+ for (i=0;i<cnt; i++)
+ descr = descr->next;
+
+ /* Set the new watermark, clear the old wtermark */
+ descr->dmac_cmd_status |= SPIDER_NET_DESCR_TXDESFLG;
+ if (card->low_watermark && card->low_watermark != descr)
+ card->low_watermark->dmac_cmd_status =
+ card->low_watermark->dmac_cmd_status & ~SPIDER_NET_DESCR_TXDESFLG;
+ card->low_watermark = descr;
+}
+
/**
* spider_net_release_tx_chain - processes sent tx descriptors
* @card: adapter structure
@@ -720,6 +753,7 @@ spider_net_release_tx_chain(struct spide
{
struct spider_net_descr_chain *chain = &card->tx_chain;
int status;
+ int rc=0;
spider_net_read_reg(card, SPIDER_NET_GDTDMACCNTR);
@@ -732,8 +766,10 @@ spider_net_release_tx_chain(struct spide
break;
case SPIDER_NET_DESCR_CARDOWNED:
- if (!brutal)
- return 1;
+ if (!brutal) {
+ rc = 1;
+ goto done;
+ }
/* fallthrough, if we release the descriptors
* brutally (then we don't care about
* SPIDER_NET_DESCR_CARDOWNED) */
@@ -750,12 +786,15 @@ spider_net_release_tx_chain(struct spide
default:
card->netdev_stats.tx_dropped++;
- return 1;
+ rc = 1;
+ goto done;
}
spider_net_release_tx_descr(card);
}
-
- return 0;
+done:
+ if (rc == 1)
+ spider_net_set_low_watermark(card);
+ return rc;
}
/**
@@ -1460,6 +1499,10 @@ spider_net_interrupt(int irq, void *ptr,
spider_net_rx_irq_off(card);
netif_rx_schedule(netdev);
}
+ if (status_reg & SPIDER_NET_TXINT ) {
+ spider_net_cleanup_tx_ring(card);
+ netif_wake_queue(netdev);
+ }
if (status_reg & SPIDER_NET_ERRINT )
spider_net_handle_error_irq(card, status_reg);
@@ -1621,6 +1664,9 @@ spider_net_open(struct net_device *netde
if (spider_net_init_chain(card, &card->tx_chain, card->descr,
PCI_DMA_TODEVICE, card->tx_desc))
goto alloc_tx_failed;
+
+ card->low_watermark = NULL;
+
if (spider_net_init_chain(card, &card->rx_chain,
card->descr + card->rx_desc,
PCI_DMA_FROMDEVICE, card->rx_desc))
diff -puN drivers/net/spider_net.h~powerpc-cell-spidernet-low-watermark-patch drivers/net/spider_net.h
--- a/drivers/net/spider_net.h~powerpc-cell-spidernet-low-watermark-patch
+++ a/drivers/net/spider_net.h
@@ -47,7 +47,7 @@ extern char spider_net_driver_name[];
#define SPIDER_NET_TX_DESCRIPTORS_MIN 16
#define SPIDER_NET_TX_DESCRIPTORS_MAX 512
-#define SPIDER_NET_TX_TIMER 20
+#define SPIDER_NET_TX_TIMER (HZ/5)
#define SPIDER_NET_RX_CSUM_DEFAULT 1
@@ -209,7 +209,7 @@ extern char spider_net_driver_name[];
#define SPIDER_NET_DMA_RX_FEND_VALUE 0x00030003
/* to set TX_DMA_EN */
#define SPIDER_NET_TX_DMA_EN 0x80000000
-#define SPIDER_NET_GDTDCEIDIS 0x00000302
+#define SPIDER_NET_GDTDCEIDIS 0x00000300
#define SPIDER_NET_DMA_TX_VALUE SPIDER_NET_TX_DMA_EN | \
SPIDER_NET_GDTDCEIDIS
#define SPIDER_NET_DMA_TX_FEND_VALUE 0x00030003
@@ -349,6 +349,7 @@ enum spider_net_int2_status {
#define SPIDER_NET_DESCR_FORCE_END 0x50000000 /* used in rx and tx */
#define SPIDER_NET_DESCR_CARDOWNED 0xA0000000 /* used in rx and tx */
#define SPIDER_NET_DESCR_NOT_IN_USE 0xF0000000
+#define SPIDER_NET_DESCR_TXDESFLG 0x00800000
struct spider_net_descr {
/* as defined by the hardware */
@@ -433,6 +434,7 @@ struct spider_net_card {
struct spider_net_descr_chain tx_chain;
struct spider_net_descr_chain rx_chain;
+ struct spider_net_descr *low_watermark;
struct net_device_stats netdev_stats;
_
Patches currently in -mm which might be from linas@xxxxxxxxxxxxxx are
origin.patch
powerpc-cell-spidernet-low-watermark-patch.patch
powerpc-cell-spidernet-stop-error-printing-patch.patch
powerpc-cell-spidernet-ethtool-i-version-number-info.patch
powerpc-cell-spidernet-ethtool-i-version-number.patch
powerpc-cell-spidernet-refine-locking.patch
git-powerpc.patch
pci-error-recovery-symbios-scsi-device-driver.patch
-
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