On Sun, Jun 09, 2024 at 01:32:38PM +0100, Marc Zyngier wrote: > On Sat, 08 Jun 2024 10:01:52 +0100, > Manivannan Sadhasivam <mani@xxxxxxxxxx> wrote: > > > > On Mon, Dec 11, 2023 at 04:52:54PM +0800, Jianjun Wang wrote: > > > Use dmam_alloc_coherent() to allocate the MSI address, instead of using > > > virt_to_phys(). > > > > What is the reason for this change? So now PCIE_MSI_VECTOR becomes unused? > > More importantly, this is yet another example of the DW reference > driver nonsense, where memory is allocated for *MSI*, while the whole > point of MSIs is that it is a write that doesn't target memory, making > any form of RAM allocation absolutely pointless. > > This silly approach has been cargo-culted for years, and while I > caught a few in my time, you can't beat copy-paste. > > IMO, this patch is only making things worse instead of fixing things. Probably partly my fault. I think there are two pieces here: 1) allocating the MSI address 2) computing the PCI bus address I don't know how to do 1), but I do encourage people not to use virt_to_phys() for 2), since (in general) CPU physical addresses are not the same as PCI bus addresses.
