On Tue, Nov 21, 2023 at 02:05:56PM -0800, Stanislav Kinsburskii wrote: > On Tue, Nov 21, 2023 at 03:37:55PM -0600, Bjorn Helgaas wrote: > > On Mon, Nov 20, 2023 at 03:40:33PM -0800, Stanislav Kinsburskii wrote: > > > Explicitly cast __iomem pointer to const void* with __force to fix the > > > following warning: > > > > > > warning: incorrect type in argument 1 (different address spaces) > > > expected void const volatile *address > > > got void [noderef] __iomem * > > > > I have two questions about this: > > > > 1) There's no other use of __force in drivers/pci, so I don't know > > what's special about pcie-mediatek.c. There should be a way to fix > > the types so it's not needed. > > __force suppreses the following sparse warning: > > warning: cast removes address space '__iomem' of expression I'm suggesting that the cast is a band-aid that covers up a type mismatch, and there shouldn't be a mismatch in the first place. > > 2) virt_to_phys() is not quite right to begin with because what we > > want is a *bus* address, not the CPU physical address we get from > > virt_to_phys(). Obviously the current platforms that use this must > > not apply any offset between bus and CPU physical addresses, but > > it's not something we should rely on. > > > > There are only three drivers (pci-aardvark.c, pcie-xilinx.c, and > > this one) that use virt_to_phys(), and they're all slightly wrong > > here. > > > > The *_compose_msi_msg() methods could use a little more consistency > > across the board. > > Could you elaborate on what do you suggest? > Should virt_to_phys() be simply removed? The DMA API (Documentation/core-api/dma-api.rst) is the usual way to get bus addresses, since an MSI is basically a DMA on the PCI bus. https://lore.kernel.org/linux-pci/20230914203146.GA77870@bhelgaas/ Nobody is very motivated to fix these, I guess ;) I sort of hate to just throw in a cast to shut up the warning because it doesn't really solve the problem. > > > Signed-off-by: Stanislav Kinsburskii <skinsburskii@xxxxxxxxxxxxxxxxxxx> > > > --- > > > drivers/pci/controller/pcie-mediatek.c | 4 ++-- > > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > > > diff --git a/drivers/pci/controller/pcie-mediatek.c b/drivers/pci/controller/pcie-mediatek.c > > > index 66a8f73296fc..27f0f79810a1 100644 > > > --- a/drivers/pci/controller/pcie-mediatek.c > > > +++ b/drivers/pci/controller/pcie-mediatek.c > > > @@ -397,7 +397,7 @@ static void mtk_compose_msi_msg(struct irq_data *data, struct msi_msg *msg) > > > phys_addr_t addr; > > > > > > /* MT2712/MT7622 only support 32-bit MSI addresses */ > > > - addr = virt_to_phys(port->base + PCIE_MSI_VECTOR); > > > + addr = virt_to_phys((__force const void *)port->base + PCIE_MSI_VECTOR); > > > msg->address_hi = 0; > > > msg->address_lo = lower_32_bits(addr); > > > > > > @@ -520,7 +520,7 @@ static void mtk_pcie_enable_msi(struct mtk_pcie_port *port) > > > u32 val; > > > phys_addr_t msg_addr; > > > > > > - msg_addr = virt_to_phys(port->base + PCIE_MSI_VECTOR); > > > + msg_addr = virt_to_phys((__force const void *)port->base + PCIE_MSI_VECTOR); > > > val = lower_32_bits(msg_addr); > > > writel(val, port->base + PCIE_IMSI_ADDR);
