[PATCH v2] riscv: Kconfig: do not select PCI_MSI if CONIFG_PCI is enabled

[Christoph Hellwig]

On Wed, Jul 21, 2021 at 11:39:12AM +0800, Vincent Chen wrote:
> The CONFIG_PCI_MSI is used to allow device drivers to enable MSI. The MSI
> enables a device to generate an interrupt using an inbound Memory Write
> on its PCI bus instead of asserting a device IRQ pin. The whole mechanism
> needs support from the PCI controller or generic interrupt controller and
> the corresponding software driver.
> 
> The RISC-V Kconfig file actively selects the PCI_MSI  if users enable
> CONFIG_PCI. However, the RISC-V specification does not require every RISC-V
> platform shall have MSI support. In other words, Kconfig enables CONFIG_PCI
> to allow PCI devices to use MSI, but due to lack of MSI support, the kernel
> may not have any function to deal with the MSI from PCI devices. When this
> case happens, it leads to the following warning message displayed in
> booting a v5.10~v5.12 kernel.

So make sure the runtime detection works fine.  An x86 kernel with
CONFIG_PCI_MSI also works on non-MSI systems.

NAK to this patch.