On 2014/9/25 18:38, Thomas Gleixner wrote:

On Thu, 25 Sep 2014, Yijing Wang wrote:

quoted

Introduce weak arch_find_msi_chip() to find the match msi_chip.
Currently, MSI chip associates pci bus to msi_chip. Because in
ARM platform, there may be more than one MSI controller in system.
Associate pci bus to msi_chip help pci device to find the match
msi_chip and setup MSI/MSI-X irq correctly. But in other platform,
like in x86. we only need one MSI chip, because all device use
the same MSI address/data and irq etc. So it's no need to associate
pci bus to MSI chip, just use a arch function, arch_find_msi_chip()
to return the MSI chip for simplicity. The default weak
arch_find_msi_chip() used in ARM platform, find the MSI chip
by pci bus.

This is really backwards. On one hand you try to get rid of the weak
arch functions zoo and then you invent new ones for no good
reason. Why can't x86 store the chip in the pci bus?

Hi Thomas, I introduced this weak function , because I thought all platforms
except arm always have only one msi chip, and I hoped to provide a simplest
solution, less code changes. I consider several solutions to associate msi chip
and PCI device. In my reply to Thierry in first reply,
http://marc.info/?l=linux-pci&m=141169658208255&w=2
Could you give me some advices ?

Thanks!
Yijing.

Looking deeper, I'm questioning the whole notion of different
msi_chips. Are this really different MSI controllers with a different
feature set or are this defacto multiple instances of the same
controller which just need a different data set?

Thanks,

	tglx

.

-- 
Thanks!
Yijing