linux-kernel - Re: [PATCH 1/6] irqchip: add the Alpine MSIX interrupt controller

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Message-ID: <20160208141754.GG4117@kwain>
Date:	Mon, 8 Feb 2016 15:17:54 +0100
From:	Antoine Tenart <antoine.tenart@...e-electrons.com>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Antoine Tenart <antoine.tenart@...e-electrons.com>,
	jason@...edaemon.net, marc.zyngier@....com,
	tsahee@...apurnalabs.com, rshitrit@...apurnalabs.com,
	thomas.petazzoni@...e-electrons.com,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/6] irqchip: add the Alpine MSIX interrupt controller

Thomas,

On Mon, Feb 08, 2016 at 11:31:47AM +0100, Thomas Gleixner wrote:
> On Mon, 8 Feb 2016, Antoine Tenart wrote:
> > +static int alpine_msix_set_affinity(struct irq_data *irq_data,
> > +				    const struct cpumask *mask, bool force)
> > +{
> > +	int ret;
> > +
> > +	ret = irq_chip_set_affinity_parent(irq_data, mask, force);
> > +	return ret == IRQ_SET_MASK_OK ? IRQ_SET_MASK_OK_DONE : ret;
> 
> What's the point of this exercise? Why can't you just set the affinity
> callback to irq_chip_set_affinity_parent() ?

That's what done in irq-gic-v2m.c. Besides that, I see no point. I'll
update for v2.

> > +static struct irq_chip alpine_msix_irq_chip = {
> > +	.name			= "MSIx",
> > +	.irq_mask		= alpine_msix_mask_msi_irq,
> > +	.irq_unmask		= alpine_msix_unmask_msi_irq,
> > +	.irq_eoi		= irq_chip_eoi_parent,
> > +	.irq_set_affinity	= alpine_msix_set_affinity,
> > +};
> > +
> > +static int alpine_msix_allocate_sgi(struct alpine_msix_data *priv, int num_req)
> > +{
> > +	int first, i;
> > +
> > +	spin_lock(&priv->msi_map_lock);
> > +
> > +	first = bitmap_find_next_zero_area(priv->msi_map, priv->num_spis, 0,
> > +					   num_req, 0);
> > +	if (first >= priv->num_spis) {
> > +		spin_unlock(&priv->msi_map_lock);
> > +		return -ENOSPC;
> > +	}
> > +
> > +	for (i = 0; i < num_req; i++)
> > +		set_bit(first + i, priv->msi_map);
> 
>   bitmap_set() ??

Indeed, that's better :)

> > +	spin_unlock(&priv->msi_map_lock);
> > +
> > +	return priv->spi_first + first;
> > +}
> > +
> > +static void alpine_msix_free_sgi(struct alpine_msix_data *priv, unsigned sgi,
> > +				 int num_req)
> > +{
> > +	int i, first;
> > +
> > +	first = sgi - priv->spi_first;
> > +
> > +	spin_lock(&priv->msi_map_lock);
> > +
> > +	for (i = 0; i < num_req; i++)
> > +		clear_bit(first + i, priv->msi_map);
> 
>   bitmap_clear() ??

Ditto.

Antoine

-- 
Antoine Ténart, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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