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Commit 73b82bf0 authored by Thommy Jakobsson's avatar Thommy Jakobsson Committed by John W. Linville
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B43: Handle DMA RX descriptor underrun 



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: default avatarMichael Buesch <m@bues.ch>
Signed-off-by: default avatarThommy Jakobsson <thommyj@gmail.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent db178340

drivers/net/wireless/b43/dma.c

+19 −0
Original line number Diff line number Diff line
@@ -1733,6 +1733,25 @@ static void dma_rx(struct b43_dmaring *ring, int *slot) 
	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;

drivers/net/wireless/b43/dma.h

+3 −1
Original line number Diff line number Diff line
@@ -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,

drivers/net/wireless/b43/main.c

+18 −25
Original line number Diff line number Diff line
@@ -1902,12 +1902,9 @@ 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",

	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]);
@@ -1918,15 +1915,6 @@ static void b43_do_interrupt_thread(struct b43_wldev *dev) 
		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]);

		}

	}



	if (unlikely(reason & B43_IRQ_UCODE_DEBUG))

		handle_irq_ucode_debug(dev);
@@ -1944,6 +1932,11 @@ 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);
@@ -2001,7 +1994,7 @@ 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)
@@ -3130,7 +3123,7 @@ 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);