From 1896d17f916819b8b5d145b4feef77109e78c435 Mon Sep 17 00:00:00 2001 From: Yoshihiro Shimoda Date: Wed, 18 Oct 2023 17:56:22 +0900 Subject: PCI: dwc: Add EDMA_UNROLL capability flag MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Renesas R-Car Gen4 PCIe controllers have an unexpected register value in the eDMA CTRL register. So, add a new capability flag "EDMA_UNROLL" which would force the unrolled eDMA mapping for the problematic device. Suggested-by: Serge Semin Link: https://lore.kernel.org/linux-pci/20231018085631.1121289-7-yoshihiro.shimoda.uh@renesas.com Signed-off-by: Yoshihiro Shimoda Signed-off-by: Krzysztof Wilczyński Reviewed-by: Manivannan Sadhasivam Reviewed-by: Serge Semin --- drivers/pci/controller/dwc/pcie-designware.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'drivers/pci/controller/dwc/pcie-designware.c') diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c index 2b60d20dfdf5..1f900be94556 100644 --- a/drivers/pci/controller/dwc/pcie-designware.c +++ b/drivers/pci/controller/dwc/pcie-designware.c @@ -887,8 +887,14 @@ static int dw_pcie_edma_find_chip(struct dw_pcie *pci) * Indirect eDMA CSRs access has been completely removed since v5.40a * thus no space is now reserved for the eDMA channels viewport and * former DMA CTRL register is no longer fixed to FFs. + * + * Note that Renesas R-Car S4-8's PCIe controllers for unknown reason + * have zeros in the eDMA CTRL register even though the HW-manual + * explicitly states there must FFs if the unrolled mapping is enabled. + * For such cases the low-level drivers are supposed to manually + * activate the unrolled mapping to bypass the auto-detection procedure. */ - if (dw_pcie_ver_is_ge(pci, 540A)) + if (dw_pcie_ver_is_ge(pci, 540A) || dw_pcie_cap_is(pci, EDMA_UNROLL)) val = 0xFFFFFFFF; else val = dw_pcie_readl_dbi(pci, PCIE_DMA_VIEWPORT_BASE + PCIE_DMA_CTRL); -- cgit v1.2.3