[26/65] B43: Handle DMA RX descriptor underrun

Steven Rostedt
2013-06-03T22:21:09Z

[-- Attachment #1: 0026-B43-Handle-DMA-RX-descriptor-underrun.patch --]
[-- Type: text/plain, Size: 5813 bytes --]

3.6.11.5 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Thommy Jakobsson <thommyj@gmail.com>

[ Upstream commit 73b82bf0bfbf58e6ff328d3726934370585f6e78 ]

Add handling of rx descriptor underflow. This fixes a fault that could
happen on slow machines, where data is received faster than the CPU can
handle. In such a case the device will use up all rx descriptors and
refuse to send any more data before confirming that it is ok. This
patch enables necessary interrupt to discover such a situation and will
handle them by dropping everything in the ring buffer.

Reviewed-by: Michael Buesch <m@bues.ch>
Signed-off-by: Thommy Jakobsson <thommyj@gmail.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
drivers/net/wireless/b43/dma.c | 19 +++++++++++++++++
drivers/net/wireless/b43/dma.h | 4 +++-
drivers/net/wireless/b43/main.c | 43 ++++++++++++++++-----------------------
3 files changed, 40 insertions(+), 26 deletions(-)

diff --git a/drivers/net/wireless/b43/dma.c b/drivers/net/wireless/b43/dma.c
index 92768d304..ba0738a 100644
--- a/drivers/net/wireless/b43/dma.c
+++ b/drivers/net/wireless/b43/dma.c
@@ -1730,6 +1730,25 @@ drop_recycle_buffer:
sync_descbuffer_for_device(ring, dmaaddr, ring->rx_buffersize);
}

+void b43_dma_handle_rx_overflow(struct b43_dmaring *ring)
+{
+ int current_slot, previous_slot;
+
+ B43_WARN_ON(ring->tx);
+
+ /* Device has filled all buffers, drop all packets and let TCP
+ * decrease speed.
+ * Decrement RX index by one will let the device to see all slots
+ * as free again
+ */
+ /*
+ *TODO: How to increase rx_drop in mac80211?
+ */
+ current_slot = ring->ops->get_current_rxslot(ring);
+ previous_slot = prev_slot(ring, current_slot);
+ ring->ops->set_current_rxslot(ring, previous_slot);
+}
+
void b43_dma_rx(struct b43_dmaring *ring)
{
const struct b43_dma_ops *ops = ring->ops;
diff --git a/drivers/net/wireless/b43/dma.h b/drivers/net/wireless/b43/dma.h
index 315b96e..68d5e0c 100644
--- a/drivers/net/wireless/b43/dma.h
+++ b/drivers/net/wireless/b43/dma.h
@@ -9,7 +9,7 @@
/* DMA-Interrupt reasons. */
#define B43_DMAIRQ_FATALMASK ((1 << 10) | (1 << 11) | (1 << 12) \
| (1 << 14) | (1 << 15))
-#define B43_DMAIRQ_NONFATALMASK (1 << 13)
+#define B43_DMAIRQ_RDESC_UFLOW (1 << 13)
#define B43_DMAIRQ_RX_DONE (1 << 16)

/*** 32-bit DMA Engine. ***/
@@ -295,6 +295,8 @@ int b43_dma_tx(struct b43_wldev *dev,
void b43_dma_handle_txstatus(struct b43_wldev *dev,
const struct b43_txstatus *status);

+void b43_dma_handle_rx_overflow(struct b43_dmaring *ring);
+
void b43_dma_rx(struct b43_dmaring *ring);

void b43_dma_direct_fifo_rx(struct b43_wldev *dev,
diff --git a/drivers/net/wireless/b43/main.c b/drivers/net/wireless/b43/main.c
index 46d9d4e..54ecf96 100644
--- a/drivers/net/wireless/b43/main.c
+++ b/drivers/net/wireless/b43/main.c
@@ -1895,30 +1895,18 @@ static void b43_do_interrupt_thread(struct b43_wldev *dev)
}
}

- if (unlikely(merged_dma_reason & (B43_DMAIRQ_FATALMASK |
- B43_DMAIRQ_NONFATALMASK))) {
- if (merged_dma_reason & B43_DMAIRQ_FATALMASK) {
- b43err(dev->wl, "Fatal DMA error: "
- "0x%08X, 0x%08X, 0x%08X, "
- "0x%08X, 0x%08X, 0x%08X\n",
- dma_reason[0], dma_reason[1],
- dma_reason[2], dma_reason[3],
- dma_reason[4], dma_reason[5]);
- b43err(dev->wl, "This device does not support DMA "
+ if (unlikely(merged_dma_reason & (B43_DMAIRQ_FATALMASK))) {
+ b43err(dev->wl,
+ "Fatal DMA error: 0x%08X, 0x%08X, 0x%08X, 0x%08X, 0x%08X, 0x%08X\n",
+ dma_reason[0], dma_reason[1],
+ dma_reason[2], dma_reason[3],
+ dma_reason[4], dma_reason[5]);
+ b43err(dev->wl, "This device does not support DMA "
"on your system. It will now be switched to PIO.\n");
- /* Fall back to PIO transfers if we get fatal DMA errors! */
- dev->use_pio = true;
- b43_controller_restart(dev, "DMA error");
- return;
- }
- if (merged_dma_reason & B43_DMAIRQ_NONFATALMASK) {
- b43err(dev->wl, "DMA error: "
- "0x%08X, 0x%08X, 0x%08X, "
- "0x%08X, 0x%08X, 0x%08X\n",
- dma_reason[0], dma_reason[1],
- dma_reason[2], dma_reason[3],
- dma_reason[4], dma_reason[5]);
- }
+ /* Fall back to PIO transfers if we get fatal DMA errors! */
+ dev->use_pio = true;
+ b43_controller_restart(dev, "DMA error");
+ return;
}

if (unlikely(reason & B43_IRQ_UCODE_DEBUG))
@@ -1937,6 +1925,11 @@ static void b43_do_interrupt_thread(struct b43_wldev *dev)
handle_irq_noise(dev);

/* Check the DMA reason registers for received data. */
+ if (dma_reason[0] & B43_DMAIRQ_RDESC_UFLOW) {
+ if (B43_DEBUG)
+ b43warn(dev->wl, "RX descriptor underrun\n");
+ b43_dma_handle_rx_overflow(dev->dma.rx_ring);
+ }
if (dma_reason[0] & B43_DMAIRQ_RX_DONE) {
if (b43_using_pio_transfers(dev))
b43_pio_rx(dev->pio.rx_queue);
@@ -1994,7 +1987,7 @@ static irqreturn_t b43_do_interrupt(struct b43_wldev *dev)
return IRQ_NONE;

dev->dma_reason[0] = b43_read32(dev, B43_MMIO_DMA0_REASON)
- & 0x0001DC00;
+ & 0x0001FC00;
dev->dma_reason[1] = b43_read32(dev, B43_MMIO_DMA1_REASON)
& 0x0000DC00;
dev->dma_reason[2] = b43_read32(dev, B43_MMIO_DMA2_REASON)
@@ -3098,7 +3091,7 @@ static int b43_chip_init(struct b43_wldev *dev)
b43_write32(dev, 0x018C, 0x02000000);
}
b43_write32(dev, B43_MMIO_GEN_IRQ_REASON, 0x00004000);
- b43_write32(dev, B43_MMIO_DMA0_IRQ_MASK, 0x0001DC00);
+ b43_write32(dev, B43_MMIO_DMA0_IRQ_MASK, 0x0001FC00);
b43_write32(dev, B43_MMIO_DMA1_IRQ_MASK, 0x0000DC00);
b43_write32(dev, B43_MMIO_DMA2_IRQ_MASK, 0x0000DC00);
b43_write32(dev, B43_MMIO_DMA3_IRQ_MASK, 0x0001DC00);
--
1.7.10.4