linux-kernel - Re: [PATCH 02/35] irqchip/gic-v3-its: Factor out wait_for

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Date:   Tue, 24 Sep 2019 09:58:56 +0100
From:   Andrew Murray <andrew.murray@....com>
To:     Marc Zyngier <maz@...nel.org>
Cc:     kvmarm@...ts.cs.columbia.edu, linux-kernel@...r.kernel.org,
        Eric Auger <eric.auger@...hat.com>,
        James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Subject: Re: [PATCH 02/35] irqchip/gic-v3-its: Factor out wait_for_syncr
 primitive

On Mon, Sep 23, 2019 at 07:25:33PM +0100, Marc Zyngier wrote:
> Waiting for a redistributor to have performed an operation is a
> common thing to do, and the idiom is already spread around.
> As we're going to make even more use of this, let's have a primitive
> that does just that.
> 
> Signed-off-by: Marc Zyngier <maz@...nel.org>

Reviewed-by: Andrew Murray <andrew.murray@....com>

> ---
>  drivers/irqchip/irq-gic-v3-its.c | 15 +++++++++------
>  1 file changed, 9 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
> index 62e54f1a248b..58cb233cf138 100644
> --- a/drivers/irqchip/irq-gic-v3-its.c
> +++ b/drivers/irqchip/irq-gic-v3-its.c
> @@ -1075,6 +1075,12 @@ static void lpi_write_config(struct irq_data *d, u8 clr, u8 set)
>  		dsb(ishst);
>  }
>  
> +static void wait_for_syncr(void __iomem *rdbase)
> +{
> +	while (gic_read_lpir(rdbase + GICR_SYNCR) & 1)
> +		cpu_relax();
> +}
> +
>  static void lpi_update_config(struct irq_data *d, u8 clr, u8 set)
>  {
>  	struct its_device *its_dev = irq_data_get_irq_chip_data(d);
> @@ -2757,8 +2763,7 @@ static void its_vpe_db_proxy_move(struct its_vpe *vpe, int from, int to)
>  
>  		rdbase = per_cpu_ptr(gic_rdists->rdist, from)->rd_base;
>  		gic_write_lpir(vpe->vpe_db_lpi, rdbase + GICR_CLRLPIR);
> -		while (gic_read_lpir(rdbase + GICR_SYNCR) & 1)
> -			cpu_relax();
> +		wait_for_syncr(rdbase);
>  
>  		return;
>  	}
> @@ -2914,8 +2919,7 @@ static void its_vpe_send_inv(struct irq_data *d)
>  
>  		rdbase = per_cpu_ptr(gic_rdists->rdist, vpe->col_idx)->rd_base;
>  		gic_write_lpir(vpe->vpe_db_lpi, rdbase + GICR_INVLPIR);
> -		while (gic_read_lpir(rdbase + GICR_SYNCR) & 1)
> -			cpu_relax();
> +		wait_for_syncr(rdbase);
>  	} else {
>  		its_vpe_send_cmd(vpe, its_send_inv);
>  	}
> @@ -2957,8 +2961,7 @@ static int its_vpe_set_irqchip_state(struct irq_data *d,
>  			gic_write_lpir(vpe->vpe_db_lpi, rdbase + GICR_SETLPIR);
>  		} else {
>  			gic_write_lpir(vpe->vpe_db_lpi, rdbase + GICR_CLRLPIR);
> -			while (gic_read_lpir(rdbase + GICR_SYNCR) & 1)
> -				cpu_relax();
> +			wait_for_syncr(rdbase);
>  		}
>  	} else {
>  		if (state)
> -- 
> 2.20.1
>