Re: [PATCH 6/7] mtd: nand: sunxi: add support for DMA assisted operations
From: Boris Brezillon <hidden>
Date: 2016-03-17 14:06:28
Also in:
linux-arm-kernel, linux-media, linux-spi, lkml
On Tue, 8 Mar 2016 12:15:14 +0100 Boris Brezillon [off-list ref] wrote:
quoted hunk ↗ jump to hunk
The sunxi NAND controller is able to pipeline ECC operations only when operated in DMA mode, which improves a lot NAND throughput while keeping CPU usage low. Signed-off-by: Boris Brezillon <boris.brezillon-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org> --- drivers/mtd/nand/sunxi_nand.c | 301 +++++++++++++++++++++++++++++++++++++++++- 1 file changed, 297 insertions(+), 4 deletions(-)diff --git a/drivers/mtd/nand/sunxi_nand.c b/drivers/mtd/nand/sunxi_nand.c index 07c3af7..7ba285e 100644 --- a/drivers/mtd/nand/sunxi_nand.c +++ b/drivers/mtd/nand/sunxi_nand.c
[...]
+static int sunxi_nfc_hw_ecc_write_page_dma(struct mtd_info *mtd,
+ struct nand_chip *chip,
+ const u8 *buf,
+ int oob_required,
+ int page)
+{
+ struct nand_chip *nand = mtd_to_nand(mtd);
+ struct sunxi_nfc *nfc = to_sunxi_nfc(nand->controller);
+ struct nand_ecc_ctrl *ecc = &nand->ecc;
+ struct sg_table sgt;
+ int ret, i;
+
+ ret = sunxi_nfc_wait_cmd_fifo_empty(nfc);
+ if (ret)
+ return ret;
+
+ ret = sunxi_nfc_dma_op_prepare(mtd, buf, ecc->size, ecc->steps,
+ DMA_TO_DEVICE, &sgt);
+ if (ret)
+ goto pio_fallback;
+
+ for (i = 0; i < ecc->steps; i++) {
+ const u8 *oob = nand->oob_poi + (i * (ecc->bytes + 4));
+
+ sunxi_nfc_hw_ecc_set_prot_oob_bytes(mtd, oob, i, !i, page);
+ }
+
+ sunxi_nfc_hw_ecc_enable(mtd);
+ sunxi_nfc_randomizer_config(mtd, page, false);
+ sunxi_nfc_randomizer_enable(mtd);
+
+ writel((NAND_CMD_RNDIN << 8) | NAND_CMD_PAGEPROG,
+ nfc->regs + NFC_REG_RCMD_SET);
+
+ dma_async_issue_pending(nfc->dmac);
+
+ writel(NFC_PAGE_OP | NFC_DATA_SWAP_METHOD |
+ NFC_DATA_TRANS | NFC_ACCESS_DIR,
+ nfc->regs + NFC_REG_CMD);
+
+ ret = sunxi_nfc_wait_events(nfc, NFC_CMD_INT_FLAG, true, 0);
+ if (ret)
+ dmaengine_terminate_all(nfc->dmac);
+
+ sunxi_nfc_randomizer_disable(mtd);
+ sunxi_nfc_hw_ecc_disable(mtd);
+
+ sunxi_nfc_dma_op_cleanup(mtd, DMA_FROM_DEVICE, &sgt);Should be DMA_TO_DEVICE here ^
+ + if (ret) + return ret; + + if (oob_required || (chip->options & NAND_NEED_SCRAMBLING)) + /* TODO: use DMA to transfer extra OOB bytes ? */ + sunxi_nfc_hw_ecc_write_extra_oob(mtd, chip->oob_poi, + NULL, page); + + return 0; + +pio_fallback: + return sunxi_nfc_hw_ecc_write_page(mtd, chip, buf, oob_required, page); +}
-- Boris Brezillon, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com