[PATCH v3 04/14] PCI: xilinx: Don't allocate extra memory for the MSI capture address
From: Marc Zyngier <maz@kernel.org>
Date: 2021-03-30 15:13:25
Also in:
linux-arm-kernel, linux-mediatek, linux-pci, linux-renesas-soc, linux-tegra, lkml
Subsystem:
pci native host bridge and endpoint drivers, pci subsystem, the rest · Maintainers:
Lorenzo Pieralisi, Krzysztof Wilczyński, Manivannan Sadhasivam, Bjorn Helgaas, Linus Torvalds
A long cargo-culted behaviour of PCI drivers is to allocate memory to obtain an address that is fed to the controller as the MSI capture address (i.e. the MSI doorbell). But there is no actual requirement for this address to be RAM. All it needs to be is a suitable aligned address that will *not* be DMA'd to. Use the physical address of the 'port' data structure as the MSI capture address, aligned on a 4K boundary. Tested-by: Bharat Kumar Gogada <redacted> Signed-off-by: Marc Zyngier <maz@kernel.org> --- drivers/pci/controller/pcie-xilinx.c | 18 ++++++------------ 1 file changed, 6 insertions(+), 12 deletions(-)
diff --git a/drivers/pci/controller/pcie-xilinx.c b/drivers/pci/controller/pcie-xilinx.c
index fa5baeb82653..e127a7b6e535 100644
--- a/drivers/pci/controller/pcie-xilinx.c
+++ b/drivers/pci/controller/pcie-xilinx.c@@ -94,7 +94,6 @@ * struct xilinx_pcie_port - PCIe port information * @reg_base: IO Mapped Register Base * @irq: Interrupt number - * @msi_pages: MSI pages * @dev: Device pointer * @msi_domain: MSI IRQ domain pointer * @leg_domain: Legacy IRQ domain pointer
@@ -103,7 +102,6 @@ struct xilinx_pcie_port { void __iomem *reg_base; u32 irq; - unsigned long msi_pages; struct device *dev; struct irq_domain *msi_domain; struct irq_domain *leg_domain;
@@ -274,10 +272,10 @@ static int xilinx_pcie_msi_setup_irq(struct msi_controller *chip, irq_set_msi_desc(irq, desc); - msg_addr = virt_to_phys((void *)port->msi_pages); + msg_addr = ALIGN_DOWN(virt_to_phys(port), SZ_4K); - msg.address_hi = 0; - msg.address_lo = msg_addr; + msg.address_hi = upper_32_bits(msg_addr); + msg.address_lo = lower_32_bits(msg_addr); msg.data = irq; pci_write_msi_msg(irq, &msg);
@@ -330,13 +328,9 @@ static int xilinx_pcie_enable_msi(struct xilinx_pcie_port *port) { phys_addr_t msg_addr; - port->msi_pages = __get_free_pages(GFP_KERNEL, 0); - if (!port->msi_pages) - return -ENOMEM; - - msg_addr = virt_to_phys((void *)port->msi_pages); - pcie_write(port, 0x0, XILINX_PCIE_REG_MSIBASE1); - pcie_write(port, msg_addr, XILINX_PCIE_REG_MSIBASE2); + msg_addr = ALIGN_DOWN(virt_to_phys(port), SZ_4K); + pcie_write(port, upper_32_bits(msg_addr), XILINX_PCIE_REG_MSIBASE1); + pcie_write(port, lower_32_bits(msg_addr), XILINX_PCIE_REG_MSIBASE2); return 0; }
--
2.29.2