Commit 93cd1bb4 authored by Marc Zyngier's avatar Marc Zyngier Committed by Lorenzo Pieralisi
Browse files

PCI: rcar: Don't allocate extra memory for the MSI capture address 

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.

Since the rcar platform already has a requirement that this
address should be in the first 4GB of the physical address space,
use the controller's own base address as the capture address.

Link: https://lore.kernel.org/r/20210330151145.997953-3-maz@kernel.org


Tested-by: default avatarYoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Signed-off-by: default avatarLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: default avatarYoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
parent 2c99e55f

drivers/pci/controller/pcie-rcar-host.c

+7 −11
Original line number Diff line number Diff line
@@ -36,7 +36,6 @@ struct rcar_msi { 
	DECLARE_BITMAP(used, INT_PCI_MSI_NR);

	struct irq_domain *domain;

	struct msi_controller chip;

	unsigned long pages;

	struct mutex lock;

	int irq1;

	int irq2;
@@ -680,14 +679,15 @@ static void rcar_pcie_unmap_msi(struct rcar_pcie_host *host) 
static void rcar_pcie_hw_enable_msi(struct rcar_pcie_host *host)

{

	struct rcar_pcie *pcie = &host->pcie;

	struct rcar_msi *msi = &host->msi;

	unsigned long base;

	struct device *dev = pcie->dev;

	struct resource res;



	/* setup MSI data target */

	base = virt_to_phys((void *)msi->pages);

	if (WARN_ON(of_address_to_resource(dev->of_node, 0, &res)))

		return;



	rcar_pci_write_reg(pcie, lower_32_bits(base) | MSIFE, PCIEMSIALR);

	rcar_pci_write_reg(pcie, upper_32_bits(base), PCIEMSIAUR);

	/* setup MSI data target */

	rcar_pci_write_reg(pcie, lower_32_bits(res.start) | MSIFE, PCIEMSIALR);

	rcar_pci_write_reg(pcie, upper_32_bits(res.start), PCIEMSIAUR);



	/* enable all MSI interrupts */

	rcar_pci_write_reg(pcie, 0xffffffff, PCIEMSIIER);
@@ -735,7 +735,6 @@ static int rcar_pcie_enable_msi(struct rcar_pcie_host *host) 
	}



	/* setup MSI data target */

	msi->pages = __get_free_pages(GFP_KERNEL | GFP_DMA32, 0);

	rcar_pcie_hw_enable_msi(host);



	return 0;
@@ -748,7 +747,6 @@ static int rcar_pcie_enable_msi(struct rcar_pcie_host *host) 
static void rcar_pcie_teardown_msi(struct rcar_pcie_host *host)

{

	struct rcar_pcie *pcie = &host->pcie;

	struct rcar_msi *msi = &host->msi;



	/* Disable all MSI interrupts */

	rcar_pci_write_reg(pcie, 0, PCIEMSIIER);
@@ -756,8 +754,6 @@ static void rcar_pcie_teardown_msi(struct rcar_pcie_host *host) 
	/* Disable address decoding of the MSI interrupt, MSIFE */

	rcar_pci_write_reg(pcie, 0, PCIEMSIALR);



	free_pages(msi->pages, 0);



	rcar_pcie_unmap_msi(host);

}