[PATCH] cxl: disable the lazy approach for irqs in POWERVM environment.

[Benjamin Herrenschmidt]

On Thu, 2018-03-22 at 17:37 +0100, Christophe Lombard wrote:
> The cxl driver cannot disable the interrupt at the device level and has
> to use disable_irq[_nosync] instead.
> To avoid the implementation of the lazy optimisation (the interrupt is
> marked disabled, but the hardware is left unmasked), we can disable it,
> for a particular irq line, by calling
> 'irq_set_status_flags(irq, IRQ_DISABLE_UNLAZY)'.

Why do you need that ? What's wrong with the lazy approach ? It makes
disable_irq/enable_irq faster...

You shouldn't need that unless your device is generating a *LOT* of
irqs while disabled.

> Signed-off-by: Christophe Lombard <clombard at linux.vnet.ibm.com>
> ---
>  drivers/misc/cxl/guest.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/misc/cxl/guest.c b/drivers/misc/cxl/guest.c
> index f58b4b6c..dc476e1 100644
> --- a/drivers/misc/cxl/guest.c
> +++ b/drivers/misc/cxl/guest.c
> @@ -389,6 +389,7 @@ static void disable_afu_irqs(struct cxl_context *ctx)
>  		hwirq = ctx->irqs.offset[r];
>  		for (i = 0; i < ctx->irqs.range[r]; hwirq++, i++) {
>  			virq = irq_find_mapping(NULL, hwirq);
> +			irq_set_status_flags(virq, IRQ_DISABLE_UNLAZY);
>  			disable_irq(virq);
>  		}
>  	}