Subject: [PATCH 3/6] irqchip: GICv3: Skip LPI deactivation

From: [email-masked] (Marc Zyngier)
Date: Wed, 12 Aug 2015 14:34:58 +0100

On 11/08/15 10:42, Eric Auger wrote:
> On 07/09/2015 03:19 PM, Marc Zyngier wrote:
>> Contrary to other GICv3 interrupts, LPIs do not have an active state
>> by virtue of being edge-triggered only (they only have a pending state).
>>
>> Given this, there is no point trying to deactivate them, and we can
>> skip the ICC_DIR_EL1 entierely.
>>
>> Signed-off-by: Marc Zyngier <[email-masked]>
>> ---
>>  drivers/irqchip/irq-gic-v3.c | 8 ++++++--
>>  1 file changed, 6 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
>> index 49768fc..e02592b 100644
>> --- a/drivers/irqchip/irq-gic-v3.c
>> +++ b/drivers/irqchip/irq-gic-v3.c
>> @@ -295,10 +295,14 @@ static int gic_irq_get_irqchip_state(struct irq_data *d,
>>  
>>  static void gic_eoi_irq(struct irq_data *d)
>>  {
>> -	if (static_key_true(&supports_deactivate))
>> +	if (static_key_true(&supports_deactivate)) {
>> +		/* No need to deactivate an LPI */
>> +		if (gic_irq(d) >= 8192)
> In case of EOIMode == 0, we do not call EOI. I can't understand whether
> it is an issue.

What do you mean? We definitely perform an EOI in both EOImodes...

> In 4.8.3 Properties of LPI, in 2d note it is written:
> 
> "SW must issue a write to EOI to clear the active priorities register,
> hence the CPU interface still requires an active state for LPIs, even
> through this is not necessary within the redistributor"
> 
> Eric
>> +			return;
>>  		gic_write_dir(gic_irq(d));
>> -	else
>> +	} else {
>>  		gic_write_eoir(gic_irq(d));

... right here.

Of am I missing something completely obvious?

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...