On 06/02/2015 11:55 AM, Fu Wei wrote:
+static irqreturn_t sbsa_gwdt_interrupt(int irq, void *dev_id)
+{
+ struct sbsa_gwdt *gwdt = (struct sbsa_gwdt *)dev_id;
+ struct watchdog_device *wdd = &gwdt->wdd;
+
+ if (wdd->pretimeout)
+ /* The pretimeout is valid, go panic */
+ panic("SBSA Watchdog pre-timeout");
+ else
+ /* We don't use pretimeout, trigger WS1 now*/
+ sbsa_gwdt_set_wcv(wdd, 0);
I don't like this.
If so, what is your idea ,if pretimeout == 0?
If pretimeout == 0, then WCV should be set to timeout/2. The WS0
timeout will occur after timeout/2 seconds, and the driver will ignore
it in the interrupt handler. Then after another timeout/2 seconds, WS1
will timeout and the system will reset.
the reason of using WCV as (timout - pretimeout): it can provide the
longer timeout period,
(1)If we use WOR, it can only provide 10s @ 400MHz(max).
as Guenter said earlier, the default timer out for most watchdog will
be 30s, so I think 10s limit will be a little short
(2)we can always program WCV just like ping.
(3)if a timeout arrives, WOR will be use, so use it as pretimeout, but
we still can make this pretimeout longer by programming WCV(I don't
think it's necessary)
I understand that, but like I said, I think pretimeout will be rarely
used, and so the driver should work best with pre-timeout enabled.
The triggering of the hardware reset should never depend
on an interrupt being handled properly.
if this fail, system reset in 1S, because WOR == (1s)
You should always program WCV
correctly in advance. This is especially true since pre-timeout will
probably rarely be used.
always programming WCV is doable. But I absolutely can not agree "
pre-timeout will probably rarely be used"
If so, SBSA watchdog is just a normal watchdog,
So what? What's wrong with that? Users don't have any control over
which watchdog hardware is on the SOC, and they don't care. They will
use the same watchdog software as they do on x86.
Users *want* a normal watchdog. Pre-timeout is only supported on time
watchdog hardware, so no one will standardize on it. ARM servers
supposed to be interchangeable with x86 servers. Customers are not
going to do anything special on an ARM server that they don't do on an
x86 server. I've been working in the ARM server industry for over two
years, and that's why everyone says.
This use case just
makes this HW useless.
If so, go to use SP805.
you still don't see the importance of this warning and pretimeout to a
real server.
If the software of a real server goes wrong, then you just directly restart it ,
never try to sync/protect the current data, never try to figure out
what is wrong with it.
I don't think that is a good server software.
And that is exactly why my driver treats WS0 as the real timeout, and
WS1 as a "backup" timeout. When WS0 expires, the system tries to do a
"polite" reset. If that doesn't work, then WS1 will do a hard reset.
This also allows me to have a timeout that's twice as long as your
driver, so my timeout occurs in WS0, not WS1.
At least, I don't thinks " pre-timeout will probably rarely be used"
is a good idea for a server.
in another word, in a server ,pre-timeout should always be used.
Except that few servers today support pre-timeout, so customers won't
depend on it.
You should probably do this *after* calling platform_get_irq_byname().
it just dose (pdev->) dev->driver_data = gwdt
If we got gwdt, we can do that.
But maybe I miss something(or a rule of usage), so please let know
why this has to be called *after* calling platform_get_irq_byname().
It's just so that you can avoid calling kzalloc() if the
platform_get_irq_byname() fails. It's not important.
I think I don't need to print "watchdog", dev_warn(dev, has help us on this.
If you do so , the message will be "watchdog: watchdog0: watchdog is
already enabled"
Ok.
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