mtd: rawnand: stm32_fmc2: use dma_get_slave_caps to get DMA max burst

Use dma_get_slave_caps API to get the max burst size of a DMA channel.

For MP1 SoCs, MDMA is used and the max burst size is 128.
For MP25 SoC, DMA3 is used and the max burst size is 64.
Signed-off-by: Christophe Kerello <christophe.kerello@foss.st.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20240219140505.85794-3-christophe.kerello@foss.st.com

drivers/mtd/nand/raw/stm32_fmc2_nand.c

@@ -264,6 +264,8 @@ struct stm32_fmc2_nfc {
 	struct sg_table dma_ecc_sg;
 	u8 *ecc_buf;
 	int dma_ecc_len;
+	u32 tx_dma_max_burst;
+	u32 rx_dma_max_burst;
 
 	struct completion complete;
 	struct completion dma_data_complete;
@@ -347,20 +349,26 @@ static int stm32_fmc2_nfc_select_chip(struct nand_chip *chip, int chipnr)
 	stm32_fmc2_nfc_setup(chip);
 	stm32_fmc2_nfc_timings_init(chip);
 
-	if (nfc->dma_tx_ch && nfc->dma_rx_ch) {
+	if (nfc->dma_tx_ch) {
 		memset(&dma_cfg, 0, sizeof(dma_cfg));
-		dma_cfg.src_addr = nfc->data_phys_addr[nfc->cs_sel];
 		dma_cfg.dst_addr = nfc->data_phys_addr[nfc->cs_sel];
-		dma_cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
 		dma_cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
-		dma_cfg.src_maxburst = 32;
-		dma_cfg.dst_maxburst = 32;
+		dma_cfg.dst_maxburst = nfc->tx_dma_max_burst /
+				       dma_cfg.dst_addr_width;
 
 		ret = dmaengine_slave_config(nfc->dma_tx_ch, &dma_cfg);
 		if (ret) {
 			dev_err(nfc->dev, "tx DMA engine slave config failed\n");
 			return ret;
 		}
+	}
+
+	if (nfc->dma_rx_ch) {
+		memset(&dma_cfg, 0, sizeof(dma_cfg));
+		dma_cfg.src_addr = nfc->data_phys_addr[nfc->cs_sel];
+		dma_cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+		dma_cfg.src_maxburst = nfc->rx_dma_max_burst /
+				       dma_cfg.src_addr_width;
 
 		ret = dmaengine_slave_config(nfc->dma_rx_ch, &dma_cfg);
 		if (ret) {
@@ -1545,6 +1553,7 @@ static int stm32_fmc2_nfc_setup_interface(struct nand_chip *chip, int chipnr,
 
 static int stm32_fmc2_nfc_dma_setup(struct stm32_fmc2_nfc *nfc)
 {
+	struct dma_slave_caps caps;
 	int ret = 0;
 
 	nfc->dma_tx_ch = dma_request_chan(nfc->dev, "tx");
@@ -1557,6 +1566,11 @@ static int stm32_fmc2_nfc_dma_setup(struct stm32_fmc2_nfc *nfc)
 		goto err_dma;
 	}
 
+	ret = dma_get_slave_caps(nfc->dma_tx_ch, &caps);
+	if (ret)
+		return ret;
+	nfc->tx_dma_max_burst = caps.max_burst;
+
 	nfc->dma_rx_ch = dma_request_chan(nfc->dev, "rx");
 	if (IS_ERR(nfc->dma_rx_ch)) {
 		ret = PTR_ERR(nfc->dma_rx_ch);
@@ -1567,6 +1581,11 @@ static int stm32_fmc2_nfc_dma_setup(struct stm32_fmc2_nfc *nfc)
 		goto err_dma;
 	}
 
+	ret = dma_get_slave_caps(nfc->dma_rx_ch, &caps);
+	if (ret)
+		return ret;
+	nfc->rx_dma_max_burst = caps.max_burst;
+
 	nfc->dma_ecc_ch = dma_request_chan(nfc->dev, "ecc");
 	if (IS_ERR(nfc->dma_ecc_ch)) {
 		ret = PTR_ERR(nfc->dma_ecc_ch);