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Message-ID: <20241029215159.1975844-1-chris.packham@alliedtelesis.co.nz>
Date: Wed, 30 Oct 2024 10:51:59 +1300
From: Chris Packham <chris.packham@...iedtelesis.co.nz>
To: broonie@...nel.org,
miquel.raynal@...tlin.com
Cc: linux-spi@...r.kernel.org,
linux-mtd@...ts.infradead.org,
linux-kernel@...r.kernel.org,
Chris Packham <chris.packham@...iedtelesis.co.nz>
Subject: [PATCH] spi: spi-mem: rtl-snand: Correctly handle DMA transfers
The RTL9300 has some limitations on the maximum DMA transfers possible.
For reads this is 2080 bytes (520*4) for writes this is 520 bytes. Deal
with this by splitting transfers into appropriately sized parts. Also
ensure that we are using the correct buffer when doing DMA writes.
Fixes: 42d20a6a61b8 ("spi: spi-mem: Add Realtek SPI-NAND controller")
Signed-off-by: Chris Packham <chris.packham@...iedtelesis.co.nz>
---
drivers/spi/spi-realtek-rtl-snand.c | 51 +++++++++++++++++++----------
1 file changed, 34 insertions(+), 17 deletions(-)
diff --git a/drivers/spi/spi-realtek-rtl-snand.c b/drivers/spi/spi-realtek-rtl-snand.c
index 23c42c8469e4..50b3240641e8 100644
--- a/drivers/spi/spi-realtek-rtl-snand.c
+++ b/drivers/spi/spi-realtek-rtl-snand.c
@@ -231,19 +231,25 @@ static int rtl_snand_xfer(struct rtl_snand *snand, int cs, const struct spi_mem_
static int rtl_snand_dma_xfer(struct rtl_snand *snand, int cs, const struct spi_mem_op *op)
{
+ unsigned int pos, nbytes;
int ret;
dma_addr_t buf_dma;
enum dma_data_direction dir;
- u32 trig;
+ u32 trig, len, maxlen;
+ void *buf;
ret = rtl_snand_xfer_head(snand, cs, op);
if (ret)
goto out_deselect;
if (op->data.dir == SPI_MEM_DATA_IN) {
+ maxlen = 2080;
+ buf = op->data.buf.in;
dir = DMA_FROM_DEVICE;
trig = 0;
} else if (op->data.dir == SPI_MEM_DATA_OUT) {
+ maxlen = 520;
+ buf = op->data.buf.out;
dir = DMA_TO_DEVICE;
trig = 1;
} else {
@@ -251,7 +257,7 @@ static int rtl_snand_dma_xfer(struct rtl_snand *snand, int cs, const struct spi_
goto out_deselect;
}
- buf_dma = dma_map_single(snand->dev, op->data.buf.in, op->data.nbytes, dir);
+ buf_dma = dma_map_single(snand->dev, buf, op->data.nbytes, dir);
ret = dma_mapping_error(snand->dev, buf_dma);
if (ret)
goto out_deselect;
@@ -264,26 +270,37 @@ static int rtl_snand_dma_xfer(struct rtl_snand *snand, int cs, const struct spi_
if (ret)
goto out_unmap;
- reinit_completion(&snand->comp);
+ pos = 0;
+ len = op->data.nbytes;
- ret = regmap_write(snand->regmap, SNAFDRSAR, buf_dma);
- if (ret)
- goto out_disable_int;
+ while (pos < len) {
+ nbytes = len - pos;
+ if (nbytes > maxlen)
+ nbytes = maxlen;
- ret = regmap_write(snand->regmap, SNAFDLR,
- CMR_WID(op->data.buswidth) | (op->data.nbytes & 0xffff));
- if (ret)
- goto out_disable_int;
+ reinit_completion(&snand->comp);
- ret = regmap_write(snand->regmap, SNAFDTR, trig);
- if (ret)
- goto out_disable_int;
+ ret = regmap_write(snand->regmap, SNAFDRSAR, buf_dma + pos);
+ if (ret)
+ goto out_disable_int;
- if (!wait_for_completion_timeout(&snand->comp, usecs_to_jiffies(20000)))
- ret = -ETIMEDOUT;
+ pos += nbytes;
- if (ret)
- goto out_disable_int;
+ ret = regmap_write(snand->regmap, SNAFDLR,
+ CMR_WID(op->data.buswidth) | nbytes);
+ if (ret)
+ goto out_disable_int;
+
+ ret = regmap_write(snand->regmap, SNAFDTR, trig);
+ if (ret)
+ goto out_disable_int;
+
+ if (!wait_for_completion_timeout(&snand->comp, usecs_to_jiffies(20000)))
+ ret = -ETIMEDOUT;
+
+ if (ret)
+ goto out_disable_int;
+ }
out_disable_int:
regmap_update_bits(snand->regmap, SNAFCFR, SNAFCFR_DMA_IE, 0);
--
2.47.0
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