PCI: endpoint: pci-epf-{mhi/test}: Move DMA initialization to EPC init callback

To maintain uniformity across EPF drivers, move DMA initialization to EPC
init callback. This will also allow us to deinit DMA during PERST# assert
in the further commits.

For EPC drivers without PERST#, DMA deinit will only happen during driver
unbind.

Link: https://lore.kernel.org/linux-pci/20240430-pci-epf-rework-v4-6-22832d0d456f@linaro.org
Tested-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Niklas Cassel <cassel@kernel.org>

Author: Mani-Sadhasivam

drivers/pci/endpoint/functions/pci-epf-mhi.c

@@ -753,6 +753,14 @@ static int pci_epf_mhi_epc_init(struct pci_epf *epf)
 	if (!epf_mhi->epc_features)
 		return -ENODATA;
 
+	if (info->flags & MHI_EPF_USE_DMA) {
+		ret = pci_epf_mhi_dma_init(epf_mhi);
+		if (ret) {
+			dev_err(dev, "Failed to initialize DMA: %d\n", ret);
+			return ret;
+		}
+	}
+
 	return 0;
 }
 
@@ -765,14 +773,6 @@ static int pci_epf_mhi_link_up(struct pci_epf *epf)
 	struct device *dev = &epf->dev;
 	int ret;
 
-	if (info->flags & MHI_EPF_USE_DMA) {
-		ret = pci_epf_mhi_dma_init(epf_mhi);
-		if (ret) {
-			dev_err(dev, "Failed to initialize DMA: %d\n", ret);
-			return ret;
-		}
-	}
-
 	mhi_cntrl->mmio = epf_mhi->mmio;
 	mhi_cntrl->irq = epf_mhi->irq;
 	mhi_cntrl->mru = info->mru;

drivers/pci/endpoint/functions/pci-epf-test.c

@@ -737,6 +737,12 @@ static int pci_epf_test_epc_init(struct pci_epf *epf)
 	bool linkup_notifier = false;
 	int ret;
 
+	epf_test->dma_supported = true;
+
+	ret = pci_epf_test_init_dma_chan(epf_test);
+	if (ret)
+		epf_test->dma_supported = false;
+
 	if (epf->vfunc_no <= 1) {
 		ret = pci_epc_write_header(epc, epf->func_no, epf->vfunc_no, header);
 		if (ret) {
@@ -883,12 +889,6 @@ static int pci_epf_test_bind(struct pci_epf *epf)
 	if (ret)
 		return ret;
 
-	epf_test->dma_supported = true;
-
-	ret = pci_epf_test_init_dma_chan(epf_test);
-	if (ret)
-		epf_test->dma_supported = false;
-
 	return 0;
 }