diff options
Diffstat (limited to 'drivers/spi/spi-tegra20-slink.c')
| -rw-r--r-- | drivers/spi/spi-tegra20-slink.c | 25 |
1 files changed, 10 insertions, 15 deletions
diff --git a/drivers/spi/spi-tegra20-slink.c b/drivers/spi/spi-tegra20-slink.c index 1427f343b39a..111fffc91435 100644 --- a/drivers/spi/spi-tegra20-slink.c +++ b/drivers/spi/spi-tegra20-slink.c @@ -1,19 +1,8 @@ +// SPDX-License-Identifier: GPL-2.0-only /* * SPI driver for Nvidia's Tegra20/Tegra30 SLINK Controller. * * Copyright (c) 2012, NVIDIA CORPORATION. All rights reserved. - * - * This program is free software; you can redistribute it and/or modify it - * under the terms and conditions of the GNU General Public License, - * version 2, as published by the Free Software Foundation. - * - * This program is distributed in the hope it will be useful, but WITHOUT - * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or - * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for - * more details. - * - * You should have received a copy of the GNU General Public License - * along with this program. If not, see <http://www.gnu.org/licenses/>. */ #include <linux/clk.h> @@ -717,9 +706,6 @@ static int tegra_slink_start_transfer_one(struct spi_device *spi, command2 = tspi->command2_reg; command2 &= ~(SLINK_RXEN | SLINK_TXEN); - tegra_slink_writel(tspi, command, SLINK_COMMAND); - tspi->command_reg = command; - tspi->cur_direction = 0; if (t->rx_buf) { command2 |= SLINK_RXEN; @@ -729,9 +715,18 @@ static int tegra_slink_start_transfer_one(struct spi_device *spi, command2 |= SLINK_TXEN; tspi->cur_direction |= DATA_DIR_TX; } + + /* + * Writing to the command2 register bevore the command register prevents + * a spike in chip_select line 0. This selects the chip_select line + * before changing the chip_select value. + */ tegra_slink_writel(tspi, command2, SLINK_COMMAND2); tspi->command2_reg = command2; + tegra_slink_writel(tspi, command, SLINK_COMMAND); + tspi->command_reg = command; + if (total_fifo_words > SLINK_FIFO_DEPTH) ret = tegra_slink_start_dma_based_transfer(tspi, t); else |