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From: Vidya Sagar <vidyas@nvidia.com>
To: <jingoohan1@gmail.com>, <gustavo.pimentel@synopsys.com>,
	<lorenzo.pieralisi@arm.com>, <bhelgaas@google.com>,
	<robh@kernel.org>, <treding@nvidia.com>, <jonathanh@nvidia.com>
Cc: <linux-pci@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<kthota@nvidia.com>, <mmaddireddy@nvidia.com>,
	<vidyas@nvidia.com>, <sagar.tv@gmail.com>
Subject: [PATCH] PCI: dwc: Set 32-bit DMA mask for MSI target address allocation
Date: Tue, 17 Nov 2020 22:23:12 +0530	[thread overview]
Message-ID: <20201117165312.25847-1-vidyas@nvidia.com> (raw)

Set DMA mask to 32-bit while allocating the MSI target address so that
the address is usable for both 32-bit and 64-bit MSI capable devices.
Throw a warning if it fails to set the mask to 32-bit to alert that
devices that are only 32-bit MSI capable may not work properly.

Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
---
Given the other patch that I've pushed to the MSI sub-system
http://patchwork.ozlabs.org/project/linux-pci/patch/20201117145728.4516-1-vidyas@nvidia.com/
which is going to catch any mismatch between MSI capability (32-bit) of the
device and system's inability to allocate the required MSI target address,
I'm not sure how much sense is this patch going to be make. But, I can
certainly say that if the memory allocation mechanism gives the addresses
from 64-bit pool by default, this patch at least makes sure that MSI target
address is allocated from 32-bit pool.

 drivers/pci/controller/dwc/pcie-designware-host.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index 44c2a6572199..e6a230eddf66 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -388,6 +388,14 @@ int dw_pcie_host_init(struct pcie_port *pp)
 							    dw_chained_msi_isr,
 							    pp);
 
+			ret = dma_set_mask(pci->dev, DMA_BIT_MASK(32));
+			if (!ret) {
+				dev_warn(pci->dev,
+					 "Failed to set DMA mask to 32-bit. "
+					 "Devices with only 32-bit MSI support"
+					 " may not work properly\n");
+			}
+
 			pp->msi_data = dma_map_single_attrs(pci->dev, &pp->msi_msg,
 						      sizeof(pp->msi_msg),
 						      DMA_FROM_DEVICE,
-- 
2.17.1


             reply	other threads:[~2020-11-17 16:53 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-17 16:53 Vidya Sagar [this message]
2020-12-03  5:02 ` [PATCH] PCI: dwc: Set 32-bit DMA mask for MSI target address allocation Vidya Sagar
2020-12-07 20:32 ` Robin Murphy
2020-12-10 11:48 ` Lorenzo Pieralisi

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