PCI: dwc: Fix scheduling while atomic issues

When programming the inbound/outbound ATUs, we call usleep_range() after
each checking PCIE_ATU_ENABLE bit. Unfortunately, the ATU programming
can be executed in atomic context:

inbound ATU programming could be called through
pci_epc_write_header()
  =>dw_pcie_ep_write_header()
    =>dw_pcie_prog_inbound_atu()

outbound ATU programming could be called through
pci_bus_read_config_dword()
  =>dw_pcie_rd_conf()
    =>dw_pcie_prog_outbound_atu()

Fix this issue by calling mdelay() instead.

Fixes: f8aed6ec624f ("PCI: dwc: designware: Add EP mode support")
Fixes: d8bbeb39fbf3 ("PCI: designware: Wait for iATU enable")
Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
[lorenzo.pieralisi@arm.com: commit log update]
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com>

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

@@ -135,7 +135,7 @@ static void dw_pcie_prog_outbound_atu_unroll(struct dw_pcie *pci, int index,
 		if (val & PCIE_ATU_ENABLE)
 			return;
 
-		usleep_range(LINK_WAIT_IATU_MIN, LINK_WAIT_IATU_MAX);
+		mdelay(LINK_WAIT_IATU);
 	}
 	dev_err(pci->dev, "Outbound iATU is not being enabled\n");
 }
@@ -178,7 +178,7 @@ void dw_pcie_prog_outbound_atu(struct dw_pcie *pci, int index, int type,
 		if (val & PCIE_ATU_ENABLE)
 			return;
 
-		usleep_range(LINK_WAIT_IATU_MIN, LINK_WAIT_IATU_MAX);
+		mdelay(LINK_WAIT_IATU);
 	}
 	dev_err(pci->dev, "Outbound iATU is not being enabled\n");
 }
@@ -236,7 +236,7 @@ static int dw_pcie_prog_inbound_atu_unroll(struct dw_pcie *pci, int index,
 		if (val & PCIE_ATU_ENABLE)
 			return 0;
 
-		usleep_range(LINK_WAIT_IATU_MIN, LINK_WAIT_IATU_MAX);
+		mdelay(LINK_WAIT_IATU);
 	}
 	dev_err(pci->dev, "Inbound iATU is not being enabled\n");
 
@@ -282,7 +282,7 @@ int dw_pcie_prog_inbound_atu(struct dw_pcie *pci, int index, int bar,
 		if (val & PCIE_ATU_ENABLE)
 			return 0;
 
-		usleep_range(LINK_WAIT_IATU_MIN, LINK_WAIT_IATU_MAX);
+		mdelay(LINK_WAIT_IATU);
 	}
 	dev_err(pci->dev, "Inbound iATU is not being enabled\n");
 

drivers/pci/controller/dwc/pcie-designware.h

@@ -26,8 +26,7 @@
 
 /* Parameters for the waiting for iATU enabled routine */
 #define LINK_WAIT_MAX_IATU_RETRIES	5
-#define LINK_WAIT_IATU_MIN		9000
-#define LINK_WAIT_IATU_MAX		10000
+#define LINK_WAIT_IATU			9
 
 /* Synopsys-specific PCIe configuration registers */
 #define PCIE_PORT_LINK_CONTROL		0x710