Len Brown wrote:
diff --git a/drivers/dma/ioat_dma.c b/drivers/dma/ioat_dma.c
index bc8c6e3..f8396ca 100644
--- a/drivers/dma/ioat_dma.c
+++ b/drivers/dma/ioat_dma.c
@@ -171,6 +171,9 @@ static int ioat_dma_enumerate_channels(struct ioatdma_device *device)
xfercap_scale = readb(device->reg_base + IOAT_XFERCAP_OFFSET);
xfercap = (xfercap_scale == 0 ? -1 : (1UL << xfercap_scale));
+#if CONFIG_I7300_IDLE_IOAT_CHANNEL
+ device->common.chancnt--;
+#endif
I still think this lone decrement looks fishy. Can there please be some
explanation how it exactly relates to the i7300 idle driver, where the
matching increment is, etc.?
+config I7300_IDLE
+ tristate "Intel chipset idle power saving driver"
It would be probably good to mention the word memory here.
+ select I7300_IDLE_IOAT_CHANNEL
+ depends on X86_64
+ help
+ Enable idle power savings with certain Intel server chipsets.
And here too.
+ The chipset must have I/O AT support, such as the Intel 7300.
+ The power savings depends on the type and quantity of DRAM devices.
+static int debug;
+module_param_named(debug, debug, uint, 0644);
+MODULE_PARM_DESC(debug, "Enable debug printks in this driver");
+#define dprintk(fmt, arg...) \
+ do { if (debug) printk(KERN_INFO I7300_PRINT fmt, ##arg); } while (0)
2.6.28 just got a new dynamic printk facility, which could be used.
+
+/*
+ * Value to set THRTLOW to when initiating throttling
+ * 0 = No throttling
+ * 1 = Throttle when > 4 activations per eval window (Maximum throttling)
+ * 2 = Throttle when > 8 activations
+ * 168 = Throttle when > 168 activations (Minimum throttling)
+ */
+#define MAX_THRTLWLIMIT 168
+static uint i7300_idle_thrtlowlm = 1;
+module_param_named(thrtlwlimit, i7300_idle_thrtlowlm, uint, 0644);
Just imagining how someone would pronounce this parameter @) Will they
get damages when their tongue ends up in a knot?
+static cpumask_t idle_cpumask;
Would it make sense to cache align this field? I could imagine
it false sharing with some frequently written variable could be quite
bad.
+ writeb(IOAT_CHANCMD_RESET, ioat_chanbase + IOAT1_CHANCMD_OFFSET);
+ writeb(IOAT_CHANCMD_START, ioat_chanbase + IOAT1_CHANCMD_OFFSET);
+
+ udelay(1000);
+
+ chan_sts = readq(ioat_chanbase + IOAT1_CHANSTS_OFFSET) &
+ IOAT_CHANSTS_DMA_TRANSFER_STATUS;
Wouldn't it be better to poll here instead of udelay?
+ /* Wait for a while for the channel to halt before releasing */
+ for (i = 0; i < 10; i++) {
+ writeb(IOAT_CHANCMD_RESET,
+ ioat_chanbase + IOAT1_CHANCMD_OFFSET);
+
+ chan_sts = readq(ioat_chanbase + IOAT1_CHANSTS_OFFSET) &
+ IOAT_CHANSTS_DMA_TRANSFER_STATUS;
+
+ if (chan_sts != IOAT_CHANSTS_DMA_TRANSFER_STATUS_ACTIVE) {
+ writew(0, ioat_chanbase + IOAT_CHANCTRL_OFFSET);
+ break;
+ }
+ udelay(1000);
Same here.
+ spin_lock_irqsave(&i7300_idle_lock, flags);
This lock still scares me. In the worst case with very frequent
idle frequencies this could bounce around a lot.
It would be better to only invoke it less frequently,
i.e. when the driver determines there is a long idle
time coming up.
+/* Check for known platforms with I/O-AT */
+static int __init i7300_idle_platform_probe(void)
+{
+ int i;
+
+ fbd_dev = pci_get_bus_and_slot(MEMCTL_BUS, MEMCTL_DEVFN)
Is there a specific reason you cannot match this by pci vendor/devid
like all standard drivers do?
If there is a good reason add a comment.
;
+static void __exit i7300_idle_exit(void)
+{
+ idle_notifier_unregister(&i7300_idle_nb);
I still think this needs some kind of idle synchronization.
-Andi
--
To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
