Re: designware/imx6: question regarding MSI

[Jingoo Han <jg1.han@samsung.com>]

On Thursday, January 23, 2014 5:39 AM, Jingoo Han wrote:
> 
> I’m currently playing with MSI support in pci-imx6.c using Harro Haan’s patch [*].
> 
> Are there any technical reasons why dw_pcie_msi_init cannot be called from dw_msi_setup_irq? Or rather,
> why it should not?

No, there is no special reason.
The patch (call dw_pcie_msi_init from dw_msi_setup_irq) would be
good. Thank you for your effort.

Mohit, Pratyush,
If you have different opinions, please let us know. :-)

Best regards,
Jingoo Han

> 
> I’m asking because I have a hotplug scenario where this little hack (call dw_pcie_msi_init from
> dw_msi_setup_irq) fixes a problem with MSI. I therefore need to understand whether it is a sensible
> hack or just crap, and more importantly; how it can be fixed properly.
> 
> Scenario:
> 
> (remove endpoints)
> # echo 1 > /sys/bus/pci/devices/0000:01:00.0/remove
> # echo 1 > /sys/bus/pci/devices/0000:01:00.1/remove
> 
> # take fpga in and out of reset (this will mess up the configuration space of the bridge)
> 
> (reset bridge)
> # echo 1 > /sys/bus/pci/devices/0000:00:00.0/reset
> 
> (rescan bus)
> # echo 1 > /sys/bus/pci/rescan
> 
> At this point everything works fine except MSI. With above mention hack it works like a charm.
> 
> I would be grateful if someone could shed light on this. I might have missed some important details.
> 
> 
> Best regards,
> Bjørn Erik Nilsen
> 
> [*]
> 
> From: Harro Haan <hrhaan@gmail.com>
> Date: Thu, 5 Dec 2013 14:06:37 +0100
> Subject: [PATCH 2/2] PCI: imx6: add support for MSI