From 5d0d16f135c0cb7a12e417cbe12b271524ce4d40 Mon Sep 17 00:00:00 2001 From: Benjamin Herrenschmidt Date: Tue, 8 May 2018 11:06:37 +1000 Subject: fsi/fsi-master-gpio: Sample input data on different clock phase We currently sample the input data right after we toggle the clock low, then high. The slave establishes the data on the rising edge, so this is not ideal. We should sample it on the low phase instead. This currently works because we have an extra delay, but subsequent patches will remove it. Signed-off-by: Benjamin Herrenschmidt Reviewed-by: Christopher Bostic Tested-by: Joel Stanley --- drivers/fsi/fsi-master-gpio.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) (limited to 'drivers/fsi/fsi-master-gpio.c') diff --git a/drivers/fsi/fsi-master-gpio.c b/drivers/fsi/fsi-master-gpio.c index 4295a46780cb..d6508bbad1fb 100644 --- a/drivers/fsi/fsi-master-gpio.c +++ b/drivers/fsi/fsi-master-gpio.c @@ -86,12 +86,15 @@ static void clock_toggle(struct fsi_master_gpio *master, int count) } } -static int sda_in(struct fsi_master_gpio *master) +static int sda_clock_in(struct fsi_master_gpio *master) { int in; ndelay(FSI_GPIO_STD_DLY); + gpiod_set_value(master->gpio_clk, 0); in = gpiod_get_value(master->gpio_data); + ndelay(FSI_GPIO_STD_DLY); + gpiod_set_value(master->gpio_clk, 1); return in ? 1 : 0; } @@ -126,8 +129,7 @@ static void serial_in(struct fsi_master_gpio *master, struct fsi_gpio_msg *msg, set_sda_input(master); for (bit = 0; bit < num_bits; bit++) { - clock_toggle(master, 1); - in_bit = sda_in(master); + in_bit = sda_clock_in(master); msg->msg <<= 1; msg->msg |= ~in_bit & 0x1; /* Data is active low */ } -- cgit v1.2.3