[PATCH 4/5] PCI: dwc: Convert eDMA channels detection to being optional

[Serge Semin]

DW HDMA controller channels can't be auto-detected. Thus there is no way
but to rely on the HDMA-capable platform drivers having the number of
channels specified. In order to permit that convert the
dw_pcie_edma_find_chan() method to executing the DMA Ctrl CSR-based number
of channels detection procedure only if no channels amount was specified,
otherwise just sanity check the specified values.

Signed-off-by: Serge Semin <fancer.lancer@xxxxxxxxx>
---
 drivers/pci/controller/dwc/pcie-designware.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
index 2243ffeb95b5..4d53a71ab1b4 100644
--- a/drivers/pci/controller/dwc/pcie-designware.c
+++ b/drivers/pci/controller/dwc/pcie-designware.c
@@ -933,12 +933,20 @@ static int dw_pcie_edma_find_chan(struct dw_pcie *pci)
 {
 	u32 val;
 
-	val = dw_pcie_readl_dma(pci, PCIE_DMA_CTRL);
+	if (!pci->edma.ll_wr_cnt && !pci->edma.ll_rd_cnt) {
+		if (pci->edma.mf == EDMA_MF_HDMA_NATIVE)
+			return -EINVAL;
+
+		val = dw_pcie_readl_dma(pci, PCIE_DMA_CTRL);
 
-	pci->edma.ll_wr_cnt = FIELD_GET(PCIE_DMA_NUM_WR_CHAN, val);
-	pci->edma.ll_rd_cnt = FIELD_GET(PCIE_DMA_NUM_RD_CHAN, val);
+		pci->edma.ll_wr_cnt = FIELD_GET(PCIE_DMA_NUM_WR_CHAN, val);
+		pci->edma.ll_rd_cnt = FIELD_GET(PCIE_DMA_NUM_RD_CHAN, val);
+	}
 
-	/* Sanity check the channels count if the mapping was incorrect */
+	/*
+	 * Sanity check the channels count in case if the mapping was
+	 * incorrectly detected/specified by the glue-driver.
+	 */
 	if (!pci->edma.ll_wr_cnt || pci->edma.ll_wr_cnt > EDMA_MAX_WR_CH ||
 	    !pci->edma.ll_rd_cnt || pci->edma.ll_rd_cnt > EDMA_MAX_RD_CH)
 		return -EINVAL;
-- 
2.43.0


--vqp52he5ger5zlrw
Content-Type: text/x-patch; charset=us-ascii
Content-Disposition: attachment;
	filename="0005-PCI-dwc-Drop-DW_PCIE_CAP_EDMA_UNROLL-flag.patch"