[PATCH 1/6] irqchip: add the Alpine MSIX interrupt controller

Marc Zyngier
2016-02-08T10:32:08Z

On 08/02/16 10:26, Antoine Tenart wrote:
>>> +static int alpine_msix_init(struct device_node *node,
>>> + struct device_node *parent)
>>> +{
>>> + struct alpine_msix_data *priv;
>>> + struct resource res;
>>> + int ret;
>>> +
>>> + priv = kzalloc(sizeof(*priv), GFP_KERNEL);
>>> + if (!priv)
>>> + return -ENOMEM;
>>> +
>>> + spin_lock_init(&priv->msi_map_lock);
>>> +
>>> + ret = of_address_to_resource(node, 0, &res);
>>> + if (ret) {
>>> + pr_err("Failed to allocate resource\n");
>>> + goto err_priv;
>>> + }
>>> +
>>> + priv->addr_high = upper_32_bits((u64)res.start);
>>> + priv->addr_low = lower_32_bits(res.start) + ALPINE_MSIX_SPI_TARGET_CLUSTER0;
>>
>> This is a bit odd. If you always set bit 16, why isn't that reflected in
>> the base address coming from the DT?
>
> The 20 least significant bits of addr_low provide direct information
> regarding the interrupt destination, so I thought it would be clearer
> to have this explicitly in the driver so that we know what those bits
> mean.

So what is this information? TARGET_CLUSTER0 is not very expressive, and
doesn't show what the alternatives are. Could you please elaborate a bit
on that front?

Thanks,

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