[PATCH v7 5/9] PCI: dwc: Avoid reading a register to detect whether eDMA exists

From: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
To: lpieralisi@kernel.org, robh+dt@kernel.org, kw@linux.com,
	bhelgaas@google.com, krzk+dt@kernel.org
Cc: marek.vasut+renesas@gmail.com, linux-pci@vger.kernel.org,
	devicetree@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
	Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Subject: [PATCH v7 5/9] PCI: dwc: Avoid reading a register to detect whether eDMA exists
Date: Mon, 21 Nov 2022 21:43:56 +0900	[thread overview]
Message-ID: <20221121124400.1282768-6-yoshihiro.shimoda.uh@renesas.com> (raw)
In-Reply-To: <20221121124400.1282768-1-yoshihiro.shimoda.uh@renesas.com>

Since reading value of PCIE_DMA_VIEWPORT_BASE + PCIE_DMA_CTRL was
0x00000000 on one of SoCs (R-Car S4-8), it cannot find the eDMA.
So, directly read the eDMA register if edma.reg_base is not zero.

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
---
 drivers/pci/controller/dwc/pcie-designware.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
index 637d01807c67..2cc8584da6f4 100644
--- a/drivers/pci/controller/dwc/pcie-designware.c
+++ b/drivers/pci/controller/dwc/pcie-designware.c
@@ -836,8 +836,7 @@ static int dw_pcie_edma_find_chip(struct dw_pcie *pci)
 {
 	u32 val;
 
-	val = dw_pcie_readl_dbi(pci, PCIE_DMA_VIEWPORT_BASE + PCIE_DMA_CTRL);
-	if (val == 0xFFFFFFFF && pci->edma.reg_base) {
+	if (pci->edma.reg_base) {
 		pci->edma.mf = EDMA_MF_EDMA_UNROLL;
 
 		val = dw_pcie_readl_dma(pci, PCIE_DMA_CTRL);
@@ -845,6 +844,7 @@ static int dw_pcie_edma_find_chip(struct dw_pcie *pci)
 		pci->edma.mf = EDMA_MF_EDMA_LEGACY;
 
 		pci->edma.reg_base = pci->dbi_base + PCIE_DMA_VIEWPORT_BASE;
+		val = dw_pcie_readl_dbi(pci, PCIE_DMA_VIEWPORT_BASE + PCIE_DMA_CTRL);
 	} else {
 		return -ENODEV;
 	}
-- 
2.25.1

