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authorChristoph Lameter <clameter@sgi.com>2007-05-16 22:10:55 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-05-17 05:23:03 -0700
commiteefaca9c3246f3daf56e7ed02987f79abcee7087 (patch)
tree1eac21979f536f7a08ae77d4b59f1c615eef5b94 /fs/stat.c
parentade3aff25fb2dce76e2a9b53e1334bd0a174f739 (diff)
downloadlinux-eefaca9c3246f3daf56e7ed02987f79abcee7087.tar.gz
SLUB: slabinfo fixes
Align the output of % with K/M/G of sizes. Check for empty NUMA information to avoid segfault on !NUMA. -r should work directly not only if we match a single slab without additional options. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/stat.c')
0 files changed, 0 insertions, 0 deletions
generated by cgit 1.2.3-korg (git 2.43.0) at 2025-12-09 06:25:03 +0000
BCM2835_DMA_INT to the CS register to acknowledge the interrupt. This clears the ACTIVE flag, so the newly issued descriptor is paused in the middle of the transaction. Because channel->desc is not NULL, the IRQ thread finalizes the descriptor and tries to start the next one. I see two possible solutions: The first is to call synchronize_irq() in bcm2835_dma_issue_pending() to wait until the IRQ thread has finished before issuing a new descriptor. The downside of this approach is unnecessary latency if clients desire rapidly terminating and re-issuing descriptors and don't have any use for an IRQ callback. (The SPI TX DMA channel is a case in point.) A better alternative is to make the IRQ thread recognize that it has missed descriptors and avoid finalizing the newly issued descriptor. So first of all, set the ACTIVE flag when acknowledging the interrupt. This keeps a newly issued descriptor running. If the descriptor was finished, the channel remains idle despite the ACTIVE flag being set. However the ACTIVE flag can then no longer be used to check whether the channel is idle, so instead check whether the register containing the current control block address is zero and finalize the current descriptor only if so. That way, there is no impact on latency and throughput if the client doesn't care for the interrupt: Only minimal additional overhead is introduced for non-cyclic descriptors as one further MMIO read is necessary per interrupt to check for idleness of the channel. Cyclic descriptors are sped up slightly by removing one MMIO write per interrupt. Fixes: 96286b576690 ("dmaengine: Add support for BCM2835") Signed-off-by: Lukas Wunner <lukas@wunner.de> Cc: stable@vger.kernel.org # v3.14+ Cc: Frank Pavlic <f.pavlic@kunbus.de> Cc: Martin Sperl <kernel@martin.sperl.org> Cc: Florian Meier <florian.meier@koalo.de> Cc: Clive Messer <clive.m.messer@gmail.com> Cc: Matthias Reichl <hias@horus.com> Tested-by: Stefan Wahren <stefan.wahren@i2se.com> Acked-by: Florian Kauer <florian.kauer@koalo.de> Signed-off-by: Vinod Koul <vkoul@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat
-rw-r--r--drivers/dma/bcm2835-dma.c33
1 files changed, 18 insertions, 15 deletions
diff --git a/drivers/dma/bcm2835-dma.c b/drivers/dma/bcm2835-dma.c
index 6204cc32d09c50..e5e37583967de7 100644
--- a/drivers/dma/bcm2835-dma.c
+++ b/drivers/dma/bcm2835-dma.c
@@ -421,7 +421,12 @@ static int bcm2835_dma_abort(void __iomem *chan_base)
long int timeout = 10000;
cs = readl(chan_base + BCM2835_DMA_CS);
- if (!(cs & BCM2835_DMA_ACTIVE))
+
+ /*
+ * A zero control block address means the channel is idle.
+ * (The ACTIVE flag in the CS register is not a reliable indicator.)
+ */
+ if (!readl(chan_base + BCM2835_DMA_ADDR))
return 0;
/* Write 0 to the active bit - Pause the DMA */
@@ -485,8 +490,15 @@ static irqreturn_t bcm2835_dma_callback(int irq, void *data)
spin_lock_irqsave(&c->vc.lock, flags);
- /* Acknowledge interrupt */
- writel(BCM2835_DMA_INT, c->chan_base + BCM2835_DMA_CS);
+ /*
+ * Clear the INT flag to receive further interrupts. Keep the channel
+ * active in case the descriptor is cyclic or in case the client has
+ * already terminated the descriptor and issued a new one. (May happen
+ * if this IRQ handler is threaded.) If the channel is finished, it
+ * will remain idle despite the ACTIVE flag being set.
+ */
+ writel(BCM2835_DMA_INT | BCM2835_DMA_ACTIVE,
+ c->chan_base + BCM2835_DMA_CS);
d = c->desc;
@@ -494,11 +506,7 @@ static irqreturn_t bcm2835_dma_callback(int irq, void *data)
if (d->cyclic) {
/* call the cyclic callback */
vchan_cyclic_callback(&d->vd);
-
- /* Keep the DMA engine running */
- writel(BCM2835_DMA_ACTIVE,
- c->chan_base + BCM2835_DMA_CS);
- } else {
+ } else if (!readl(c->chan_base + BCM2835_DMA_ADDR)) {
vchan_cookie_complete(&c->desc->vd);
bcm2835_dma_start_desc(c);
}
@@ -806,11 +814,7 @@ static int bcm2835_dma_terminate_all(struct dma_chan *chan)
list_del_init(&c->node);
spin_unlock(&d->lock);
- /*
- * Stop DMA activity: we assume the callback will not be called
- * after bcm_dma_abort() returns (even if it does, it will see
- * c->desc is NULL and exit.)
- */
+ /* stop DMA activity */
if (c->desc) {
bcm2835_dma_desc_free(&c->desc->vd);
c->desc = NULL;
@@ -818,8 +822,7 @@ static int bcm2835_dma_terminate_all(struct dma_chan *chan)
/* Wait for stopping */
while (--timeout) {
- if (!(readl(c->chan_base + BCM2835_DMA_CS) &
- BCM2835_DMA_ACTIVE))
+ if (!readl(c->chan_base + BCM2835_DMA_ADDR))
break;
cpu_relax();
generated by cgit 1.2.3-korg (git 2.43.0) at 2025-12-09 06:25:01 +0000