[PATCH 16/16] ARM: imx: enable SPARSE_IRQ for imx platform

[Shawn Guo]

On Mon, Jun 18, 2012 at 04:48:53PM +0800, Dong Aisheng wrote:
> On Thu, Jun 14, 2012 at 01:59:47PM +0800, Shawn Guo wrote:
> > As all irqchips on imx have been changed to allocate their irq_descs,
> > and all unneeded mach/irqs.h inclusions on imx have been cleaned up,
> > now it's time to select SPARSE_IRQ for imx/mxc.
> > 
> > The SPARSE_IRQ support forces irqs allocation starting from 16.  All
> > those static irq number definition for SoCs need to shift 16 to keep
> > non-DT boot works.
> > 
> It seems shift 16 is to get the correct linux virt irq, right?
Yes.

> If yes, i do not like this approach very much since it's an implicit way
> based on users know how legacy irqdomain works internally.
> 
I do not quite follow on this.  Users do not need to know how legacy
irqdomain works internally.  They are still using those static MX*_INT_*
macros.  All they need to know is there is a 16 shift between hardware
irq and Linux irq number when they look at /proc/interrupts.

> Ideally i would see we keep the code as before that still using hw irqs
> for device resource definition, but convert to linux virt irq in a standard
> irqdomain map way when adding devices by calling imx_add_platform_device.
> 
What's the point of hiding this irq number conversion in
imx_add_platform_device?  The irq number used in resource definition
should simply just be Linux irq.  Doing what you suggest here will
only confuse users when they look at /proc/interrupts and those static
IRQ definitions.

BTW, not all the platform_devices are added by calling
imx_add_platform_device on imx.

Regards,
Shawn