[PATCH] m68k/irq - use polled IRQ flag for MFP timer cascaded interrupts

[PATCH] m68k/irq - use polled IRQ flag for MFP timer cascaded interrupts

[Michael Schmitz]

Some Atari hardware has no capacity to raise interrupts (e.g.
network or USB adapter hardware attached via ROM port). The driver
interrupt routine is called from a timer interrupt (timer D) in
these cases, using chained device specific pseudo interrupts
(IRQ_MFP_TIMER1 ff.)

These interrupts will more often than not, return IRQ_NONE as
there is not always work for the device handler when called.
Too many unhandled interrupts will result in the interrupt
being disabled by the stuck interrupt watchdog.

As preferred option to flag interrupts as needing exclusion
from the watchdog mechanism, tglx added the IRQ_IS_POLLED flag
for use in such a case. Currently, two interrupts need to use
this flag. Add more users as needed.

This patch obsoletes the introduction of handle_polled_irq()
in the m68k tree.

Signed-off-By: Michael Schmitz <schmitz@debian.org>
---
 arch/m68k/atari/ataints.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/arch/m68k/atari/ataints.c b/arch/m68k/atari/ataints.c
index 90f7a48..3e73a63 100644
--- a/arch/m68k/atari/ataints.c
+++ b/arch/m68k/atari/ataints.c
@@ -330,9 +330,12 @@ void __init atari_init_IRQ(void)
 	sound_ym.rd_data_reg_sel = 7;
 	sound_ym.wd_data = 0xff;
 
-	m68k_setup_irq_controller(&atari_mfptimer_chip, handle_polled_irq,
+	m68k_setup_irq_controller(&atari_mfptimer_chip, handle_simple_irq,
 				  IRQ_MFP_TIMER1, 8);
 
+	irq_set_status_flags(IRQ_MFP_TIMER1, IRQ_IS_POLLED);
+	irq_set_status_flags(IRQ_MFP_TIMER2, IRQ_IS_POLLED);
+
 	/* prepare timer D data for use as poll interrupt */
 	/* set Timer D data Register - needs to be > 0 */
 	st_mfp.tim_dt_d = 254;	/* < 100 Hz */
-- 
1.7.0.4

Re: [PATCH] m68k/irq - use polled IRQ flag for MFP timer cascaded interrupts

[Geert Uytterhoeven]

On Sat, Jan 11, 2014 at 2:01 AM, Michael Schmitz <schmitzmic@gmail.com> wrote:
> Some Atari hardware has no capacity to raise interrupts (e.g.
> network or USB adapter hardware attached via ROM port). The driver
> interrupt routine is called from a timer interrupt (timer D) in
> these cases, using chained device specific pseudo interrupts
> (IRQ_MFP_TIMER1 ff.)
>
> These interrupts will more often than not, return IRQ_NONE as
> there is not always work for the device handler when called.
> Too many unhandled interrupts will result in the interrupt
> being disabled by the stuck interrupt watchdog.
>
> As preferred option to flag interrupts as needing exclusion
> from the watchdog mechanism, tglx added the IRQ_IS_POLLED flag
> for use in such a case. Currently, two interrupts need to use
> this flag. Add more users as needed.
>
> This patch obsoletes the introduction of handle_polled_irq()
> in the m68k tree.
>
> Signed-off-By: Michael Schmitz <schmitz@debian.org>

Thanks, will apply and queue for 3.14.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH] m68k/irq - use polled IRQ flag for MFP timer cascaded interrupts

[Michael Schmitz]

Andreas,

> Please add your explanation to the patch.

OK, will do.

Happy Xmas to all!

Cheers,

	Michael

>
> Andreas.
>
> -- 
> Andreas Schwab, schwab@linux-m68k.org
> GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 
> 4ED5
> "And now for something completely different."

Re: [PATCH] m68k/irq - use polled IRQ flag for MFP timer cascaded interrupts

[Andreas Schwab]

Please add your explanation to the patch.

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

Re: [PATCH] m68k/irq - use polled IRQ flag for MFP timer cascaded interrupts

[Michael Schmitz]

Geert,

forgot to reply to all last time ...

>>
>
> Missing SoB.

Sorry, please add:

Signed-off-By: Michael Schmitz <schmitz@debian.org>

>
>> ---
>>  arch/m68k/atari/ataints.c |    5 ++++-
>>  1 files changed, 4 insertions(+), 1 deletions(-)
>>
>> diff --git a/arch/m68k/atari/ataints.c b/arch/m68k/atari/ataints.c
>> index 90f7a48..3e73a63 100644
>> --- a/arch/m68k/atari/ataints.c
>> +++ b/arch/m68k/atari/ataints.c
>> @@ -330,9 +330,12 @@ void __init atari_init_IRQ(void)
>>         sound_ym.rd_data_reg_sel = 7;
>>         sound_ym.wd_data = 0xff;
>>
>> -       m68k_setup_irq_controller(&atari_mfptimer_chip, 
>> handle_polled_irq,
>> +       m68k_setup_irq_controller(&atari_mfptimer_chip, 
>> handle_simple_irq,
>>                                   IRQ_MFP_TIMER1, 8);
>>
>> +       irq_set_status_flags(IRQ_MFP_TIMER1, IRQ_IS_POLLED);
>> +       irq_set_status_flags(IRQ_MFP_TIMER2, IRQ_IS_POLLED);
>
> Why do you set this flag for timer 2, too? Timer D is timer1, right?
>
>

The  IRQ_MFP_TIMER1 and IRQ_MFP_TIMER2 interrupts are the multiplexed 
ones. These are the only ones currently used by EtherNEC and NetUSBee 
(if someone wants to use IRQ_MFP_TIMER3 for another piece of broken 
hardware, this one would need the same flag added).

IRQ_MFP_TIMD is the real hardware interrupt driving IRQ_MFP_TIMER1 and 
IRQ_MFP_TIMER2. It always returns IRQ_HANDLED so no flag required.

Cheers,

	Michael


>
>> +
>>         /* prepare timer D data for use as poll interrupt */
>>         /* set Timer D data Register - needs to be > 0 */
>>         st_mfp.tim_dt_d = 254;  /* < 100 Hz */
>
> Gr{oetje,eeting}s,
>
>                         Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- 
> geert@linux-m68k.org
>
> In personal conversations with technical people, I call myself a 
> hacker. But
> when I'm talking to journalists I just say "programmer" or something 
> like that.
>                                 -- Linus Torvalds
> --
> To unsubscribe from this list: send the line "unsubscribe linux-m68k" 
> in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH] m68k/irq - use polled IRQ flag for MFP timer cascaded interrupts

[Michael Schmitz]

Andreas,

> What does that fix?

Hardware with no interrupt line (EtherNEC, NetUSBee) has the driver 
interrupt routine polled from the Atari timer D interrupt, which calls 
in to the driver inthandler via driver-specific chained interrupts 
IRQ_MFP_TIMER1 etc. (see patch to set up irq chip for timer D interrupt 
earlier).

These interrupts will, more often than not, return IRQ_NONE as there's 
not always any work to be done when called from the timer. Accumulation 
of unhandled interrupts then causes the handler to be disabled by the 
unhandled interrupt watchdog.

Driver maintainers have been reluctant to accept other hacks to fix 
this issue (such as declaring the driver interrupt shared, and hooking 
up a handler that just returns IRQ_HANDLED always).

Cheers,

	Michael


>
> Andreas.
>
> -- 
> Andreas Schwab, schwab@linux-m68k.org
> GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 
> 4ED5
> "And now for something completely different."
> --
> To unsubscribe from this list: send the line "unsubscribe linux-m68k" 
> in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH] m68k/irq - use polled IRQ flag for MFP timer cascaded interrupts

[Geert Uytterhoeven]

>

Missing SoB.

> ---
>  arch/m68k/atari/ataints.c |    5 ++++-
>  1 files changed, 4 insertions(+), 1 deletions(-)
>
> diff --git a/arch/m68k/atari/ataints.c b/arch/m68k/atari/ataints.c
> index 90f7a48..3e73a63 100644
> --- a/arch/m68k/atari/ataints.c
> +++ b/arch/m68k/atari/ataints.c
> @@ -330,9 +330,12 @@ void __init atari_init_IRQ(void)
>         sound_ym.rd_data_reg_sel = 7;
>         sound_ym.wd_data = 0xff;
>
> -       m68k_setup_irq_controller(&atari_mfptimer_chip, handle_polled_irq,
> +       m68k_setup_irq_controller(&atari_mfptimer_chip, handle_simple_irq,
>                                   IRQ_MFP_TIMER1, 8);
>
> +       irq_set_status_flags(IRQ_MFP_TIMER1, IRQ_IS_POLLED);
> +       irq_set_status_flags(IRQ_MFP_TIMER2, IRQ_IS_POLLED);

Why do you set this flag for timer 2, too? Timer D is timer1, right?

> +
>         /* prepare timer D data for use as poll interrupt */
>         /* set Timer D data Register - needs to be > 0 */
>         st_mfp.tim_dt_d = 254;  /* < 100 Hz */

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds