diff options
| author | Emil Renner Berthing <kernel@esmil.dk> | 2019-04-12 12:53:20 +0200 |
|---|---|---|
| committer | Mark Brown <broonie@kernel.org> | 2019-05-08 19:32:28 +0900 |
| commit | 47300728fb213486a830565d2af49da967c9d16a (patch) | |
| tree | 5f07c2f74e4957e86fd437df0fa237e9ceb16e20 /drivers/spi | |
| parent | d5864e5bed96db7230da45463d6ae7af5b3b4399 (diff) | |
| download | linux-47300728fb213486a830565d2af49da967c9d16a.tar.bz2 | |
spi: rockchip: turn down tx dma bursts
This fixes tx and bi-directional dma transfers on rk3399-gru-kevin.
It seems the SPI fifo must have room for 2 bursts when the dma_tx_req
signal is generated or it might skip some words. This in turn makes
the rx dma channel never complete for bi-directional transfers.
Fix it by setting tx burst length to fifo_len / 4 and the dma
watermark to fifo_len / 2.
However the rk3399 TRM says (sic):
"DMAC support incrementing-address burst and fixed-address burst. But in
the case of access SPI and UART at byte or halfword size, DMAC only
support fixed-address burst and the address must be aligned to word."
So this relies on fifo_len being a multiple of 16 such that the
burst length (= fifo_len / 4) is a multiple of 4 and the addresses
will be word-aligned.
Fixes: dcfc861d24ec ("spi: rockchip: adjust dma watermark and burstlen")
Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
Signed-off-by: Mark Brown <broonie@kernel.org>
Diffstat (limited to 'drivers/spi')
| -rw-r--r-- | drivers/spi/spi-rockchip.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/spi/spi-rockchip.c b/drivers/spi/spi-rockchip.c index 3912526ead66..19f6a76f1c07 100644 --- a/drivers/spi/spi-rockchip.c +++ b/drivers/spi/spi-rockchip.c @@ -425,7 +425,7 @@ static int rockchip_spi_prepare_dma(struct rockchip_spi *rs, .direction = DMA_MEM_TO_DEV, .dst_addr = rs->dma_addr_tx, .dst_addr_width = rs->n_bytes, - .dst_maxburst = rs->fifo_len / 2, + .dst_maxburst = rs->fifo_len / 4, }; dmaengine_slave_config(master->dma_tx, &txconf); @@ -526,7 +526,7 @@ static void rockchip_spi_config(struct rockchip_spi *rs, else writel_relaxed(rs->fifo_len / 2 - 1, rs->regs + ROCKCHIP_SPI_RXFTLR); - writel_relaxed(rs->fifo_len / 2 - 1, rs->regs + ROCKCHIP_SPI_DMATDLR); + writel_relaxed(rs->fifo_len / 2, rs->regs + ROCKCHIP_SPI_DMATDLR); writel_relaxed(0, rs->regs + ROCKCHIP_SPI_DMARDLR); writel_relaxed(dmacr, rs->regs + ROCKCHIP_SPI_DMACR); |