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

From: [email-masked] (Eric Auger)
Date: Tue, 11 Aug 2015 11:42:50 +0200

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.
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));
> +	}
>  }
>  
>  static int gic_set_type(struct irq_data *d, unsigned int type)
>