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| author | Fabio Estevam <fabio.estevam@freescale.com> | 2013-04-09 13:06:25 +0000 |
|---|---|---|
| committer | Stefano Babic <sbabic@denx.de> | 2013-04-13 17:46:42 +0200 |
| commit | 0f1411bc8dade4472ca802f46f75714e67301bb0 (patch) | |
| tree | 38bb65f86352d2da7a20452e92076908b96f9faf /drivers/spi | |
| parent | 66300ac25b70018c81c931c981317f6ba390182d (diff) | |
| download | u-boot-imx-0f1411bc8dade4472ca802f46f75714e67301bb0.zip u-boot-imx-0f1411bc8dade4472ca802f46f75714e67301bb0.tar.gz u-boot-imx-0f1411bc8dade4472ca802f46f75714e67301bb0.tar.bz2 | |
spi: mxc_spi: Set master mode for all channels
The glitch in the SPI clock line, which commit 3cea335c34 (spi: mxc_spi: Fix spi
clock glitch durant reset) solved, is back now and itwas re-introduced by
commit d36b39bf0d (spi: mxc_spi: Fix ECSPI reset handling).
Actually the glitch is happening due to always toggling between slave mode
and master mode by configuring the CHANNEL_MODE bits in this reset function.
Since the spi driver only supports master mode, set the mode for all channels
always to master mode in order to have a stable, "glitch-free" SPI clock line.
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Diffstat (limited to 'drivers/spi')
| -rw-r--r-- | drivers/spi/mxc_spi.c | 17 |
1 files changed, 9 insertions, 8 deletions
diff --git a/drivers/spi/mxc_spi.c b/drivers/spi/mxc_spi.c index 4c19e0b..20419e6 100644 --- a/drivers/spi/mxc_spi.c +++ b/drivers/spi/mxc_spi.c @@ -137,11 +137,15 @@ static s32 spi_cfg_mxc(struct mxc_spi_slave *mxcs, unsigned int cs, return -1; } - /* Reset spi */ - reg_write(®s->ctrl, 0); - reg_write(®s->ctrl, MXC_CSPICTRL_EN); - - reg_ctrl = reg_read(®s->ctrl); + /* + * Reset SPI and set all CSs to master mode, if toggling + * between slave and master mode we might see a glitch + * on the clock line + */ + reg_ctrl = MXC_CSPICTRL_MODE_MASK; + reg_write(®s->ctrl, reg_ctrl); + reg_ctrl |= MXC_CSPICTRL_EN; + reg_write(®s->ctrl, reg_ctrl); /* * The following computation is taken directly from Freescale's code. @@ -174,9 +178,6 @@ static s32 spi_cfg_mxc(struct mxc_spi_slave *mxcs, unsigned int cs, reg_ctrl = (reg_ctrl & ~MXC_CSPICTRL_POSTDIV(0x0F)) | MXC_CSPICTRL_POSTDIV(post_div); - /* always set to master mode */ - reg_ctrl |= 1 << (cs + 4); - /* We need to disable SPI before changing registers */ reg_ctrl &= ~MXC_CSPICTRL_EN; |