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. [kwilczynski: commit log] Link: https://lore.kernel.org/linux-pci/20230825093219.2685912-10-yoshihiro.shimoda.uh@xxxxxxxxxxx Suggested-by: Serge Semin <fancer.lancer@xxxxxxxxx> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx> Signed-off-by: Krzysztof Wilczyński <kwilczynski@xxxxxxxxxx> Reviewed-by: Serge Semin <fancer.lancer@xxxxxxxxx> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx> --- drivers/pci/controller/dwc/pcie-designware.c | 8 +++++++- drivers/pci/controller/dwc/pcie-designware.h | 5 +++-- 2 files changed, 10 insertions(+), 3 deletions(-) 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); diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h index 6189884b4efa..e10f7e18b13a 100644 --- a/drivers/pci/controller/dwc/pcie-designware.h +++ b/drivers/pci/controller/dwc/pcie-designware.h @@ -51,8 +51,9 @@ /* DWC PCIe controller capabilities */ #define DW_PCIE_CAP_REQ_RES 0 -#define DW_PCIE_CAP_IATU_UNROLL 1 -#define DW_PCIE_CAP_CDM_CHECK 2 +#define DW_PCIE_CAP_EDMA_UNROLL 1 +#define DW_PCIE_CAP_IATU_UNROLL 2 +#define DW_PCIE_CAP_CDM_CHECK 3 #define dw_pcie_cap_is(_pci, _cap) \ test_bit(DW_PCIE_CAP_ ## _cap, &(_pci)->caps) -- 2.25.1
