On 04/08/2013 11:09 PM, Gilles Chanteperdrix wrote:
On 04/06/2013 11:43 AM, Jan Kiszka wrote:
On 2013-04-02 23:44, Gilles Chanteperdrix wrote:
On 03/27/2013 02:30 PM, Jan Kiszka wrote:
I'm wondering now why we need this differently for the I-pipe case.
Let's revisit what happens with a fasteoi normally:
- it's masked only if it's a oneshot IRQ before calling the flow handler
- it's unmasked after the flow handling if the thread was not woken up
With I-pipe we already enter handle_fasteoi_irq with the IRQ masked. The
conditions and spots to unmask are:
- from handle_fasteoi_irq if the thread wasn't woken up or we have
non-threaded or non-oneshot handling
- otherwise on end_irq from the handler thread
Do you think this is correct? If so, I do not think it matches this
patch yet.
Hi,
here is a much simpler patch:
diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index 11e75d1..a1c9918 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -421,6 +421,13 @@ static inline void preflow_handler(struct irq_desc *desc)
static inline void preflow_handler(struct irq_desc *desc) { }
#endif
+static void cond_release_fasteoi_irq(struct irq_desc *desc)
+{
+ if (desc->irq_data.chip->irq_release &&
+ !irqd_irq_disabled(&desc->irq_data) && !desc->threads_oneshot)
+ desc->irq_data.chip->irq_release(&desc->irq_data);
+}
+
/**
* handle_fasteoi_irq - irq handler for transparent controllers
* @irq: the interrupt number
@@ -463,8 +470,7 @@ handle_fasteoi_irq(unsigned int irq, struct irq_desc *desc)
#ifdef CONFIG_IPIPE
/* XXX: IRQCHIP_EOI_IF_HANDLED is ignored. */
Makes me wonder what this comment wants to tell us. That there is an
unhandled corner case or that this is intentionally ignored? I support
the latter as I-pipe already does EOI when accepting the IRQ, no? Maybe
you can clarify that line at this chance.
I have no idea where this comment come from. I do not think this flag
can be handled with the I-pipe kernel, as the EOI is sent before trying
to handle the IRQ. The only users are in arch/sparc and arch/powerpc,
maybe Philippe knows more?
Jan is right, we ignore EOI_IF_HANDLED and never send EOI from the
regular flow handler, as a consequence of doing eoi+mask when holding
the IRQ in the ipipe's flow handler.
--
Philippe.
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