Unverified Commit f3a29640 authored by Ajay Agarwal's avatar Ajay Agarwal Committed by Krzysztof Wilczyński
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PCI: dwc: Strengthen the MSI address allocation logic 

There can be platforms that do not use/have 32-bit DMA addresses.
The current implementation of 32-bit IOVA allocation can fail for
such platforms, eventually leading to the probe failure.

Try to allocate a 32-bit msi_data. If this allocation fails,
attempt a 64-bit address allocation. Please note that if the
64-bit MSI address is allocated, then the EPs supporting 32-bit
MSI address only will not work.

Link: https://lore.kernel.org/linux-pci/20240221153840.1789979-1-ajayagarwal@google.com


Tested-by: default avatarWill McVicker <willmcvicker@google.com>
Signed-off-by: default avatarAjay Agarwal <ajayagarwal@google.com>
Signed-off-by: default avatarKrzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: default avatarManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: default avatarSerge Semin <fancer.lancer@gmail.com>
Reviewed-by: default avatarWill McVicker <willmcvicker@google.com>
parent 6613476e

drivers/pci/controller/dwc/pcie-designware-host.c

+13 −8
Original line number Diff line number Diff line
@@ -328,7 +328,7 @@ static int dw_pcie_msi_host_init(struct dw_pcie_rp *pp) 
	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);

	struct device *dev = pci->dev;

	struct platform_device *pdev = to_platform_device(dev);

	u64 *msi_vaddr;

	u64 *msi_vaddr = NULL;

	int ret;

	u32 ctrl, num_ctrls;
@@ -379,16 +379,21 @@ static int dw_pcie_msi_host_init(struct dw_pcie_rp *pp) 
	 * memory.

	 */

	ret = dma_set_coherent_mask(dev, DMA_BIT_MASK(32));

	if (ret)

		dev_warn(dev, "Failed to set DMA mask to 32-bit. Devices with only 32-bit MSI support may not work properly\n");

	if (!ret)

		msi_vaddr = dmam_alloc_coherent(dev, sizeof(u64), &pp->msi_data,

						GFP_KERNEL);



	if (!msi_vaddr) {

		dev_warn(dev, "Failed to allocate 32-bit MSI address\n");

		dma_set_coherent_mask(dev, DMA_BIT_MASK(64));

		msi_vaddr = dmam_alloc_coherent(dev, sizeof(u64), &pp->msi_data,

						GFP_KERNEL);

		if (!msi_vaddr) {

		dev_err(dev, "Failed to alloc and map MSI data\n");

			dev_err(dev, "Failed to allocate MSI address\n");

			dw_pcie_free_msi(pp);

			return -ENOMEM;

		}

	}



	return 0;

}