diff options
| author | Aaron Durbin <adurbin@chromium.org> | 2014-07-21 22:11:29 -0500 |
|---|---|---|
| committer | Marc Jones <marc.jones@se-eng.com> | 2015-03-13 00:17:09 +0100 |
| commit | 44f465d21cad78c87c32b916f72e1bff2ef532a0 (patch) | |
| tree | 680ea7fe809c7994d3db75c12bb35dad21966b90 /src/soc/nvidia | |
| parent | 7ddb5f76feea37ed055f2eede944c2971214e2f2 (diff) | |
tegra132: fix Rx FIFO underruns with slower SPI clock
The SPI controller operates on packets which can be variable
length up to 32-bit packets. It also has the ability to be
put in packed or unpacked mode w.r.t each packet. i.e. does
a single fifo register hold >= 1 packet. The current programming
uses 8-bit packets in unpacked mode which means 4 fifo slots
are used for a 32-bit DMA transfter. As the AHB can only operate
on a minimum of 32-bit bursts the triggers need to be programmed
correctly so that there is room for a full 32-bit DMA transaction.
Previously faster SPI clocks just made things magically work.
BUG=chrome-os-partner:30779
BRANCH=None
TEST=Built and booted through coreboot with 20MHz SPI clock.
Original-Change-Id: I3f1cd4dddcea9514327b2363ed450a527db7e1fe
Original-Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/208862
Original-Reviewed-by: Tom Warren <twarren@nvidia.com>
Original-Reviewed-by: Furquan Shaikh <furquan@chromium.org>
Original-Commit-Queue: Furquan Shaikh <furquan@chromium.org>
(cherry picked from commit d9864228a2479e412d7e0d2221fe536f78329acd)
Signed-off-by: Marc Jones <marc.jones@se-eng.com>
Change-Id: I61c145f35e1f889d4f83f3dfea049bfd347c1196
Reviewed-on: http://review.coreboot.org/8649
Tested-by: build bot (Jenkins)
Reviewed-by: Furquan Shaikh <furquan@google.com>
Diffstat (limited to 'src/soc/nvidia')
| -rw-r--r-- | src/soc/nvidia/tegra132/spi.c | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/src/soc/nvidia/tegra132/spi.c b/src/soc/nvidia/tegra132/spi.c index f1be207ced..973bdc94ea 100644 --- a/src/soc/nvidia/tegra132/spi.c +++ b/src/soc/nvidia/tegra132/spi.c @@ -530,10 +530,24 @@ static void tegra_spi_dma_start(struct tegra_spi_channel *spi) */ setbits_le32(&spi->regs->trans_status, SPI_STATUS_RDY); - if (spi->dma_out) + /* + * The DMA triggers have units of packets. As each packet is currently + * 1 byte the triggers need to be set to 4 packets (0b01) to match + * the AHB 32-bit (4 byte) tranfser. Otherwise the FIFO errors can + * occur. + */ + if (spi->dma_out) { + clrsetbits_le32(&spi->regs->dma_ctl, + SPI_DMA_CTL_TX_TRIG_MASK << SPI_DMA_CTL_TX_TRIG_SHIFT, + 1 << SPI_DMA_CTL_TX_TRIG_SHIFT); setbits_le32(&spi->regs->command1, SPI_CMD1_TX_EN); - if (spi->dma_in) + } + if (spi->dma_in) { + clrsetbits_le32(&spi->regs->dma_ctl, + SPI_DMA_CTL_RX_TRIG_MASK << SPI_DMA_CTL_RX_TRIG_SHIFT, + 1 << SPI_DMA_CTL_RX_TRIG_SHIFT); setbits_le32(&spi->regs->command1, SPI_CMD1_RX_EN); + } /* * To avoid underrun conditions, enable APB DMA before SPI DMA for |