Re: [PATCH 1/1] Add strong pullup emulation to w1-gpio master driver.

[Evgeniy Polyakov <zbr@ioremap.net>]

Hi

11.11.2013, 18:37, "Evgeny Boger" <eugenyboger@gmail.com>:
>  Strong pullup is emulated by driving pin logic high after write command when
>  using tri-state push-pull GPIO.
>
> Signed-off-by: Evgeny Boger <boger@contactless.ru>
> ---
>  drivers/w1/masters/w1-gpio.c | 22 ++++++++++++++++++++++
>  drivers/w1/w1_int.c          | 12 ------------
>  include/linux/w1-gpio.h      |  1 +
>  3 files changed, 23 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/w1/masters/w1-gpio.c b/drivers/w1/masters/w1-gpio.c
> index f54ece2..cb7f89b 100644
> --- a/drivers/w1/masters/w1-gpio.c
> +++ b/drivers/w1/masters/w1-gpio.c
> @@ -18,10 +18,31 @@
>  #include <linux/of_gpio.h>
>  #include <linux/err.h>
>  #include <linux/of.h>
> +#include <linux/delay.h>
>
>  #include "../w1.h"
>  #include "../w1_int.h"
>
> +static u8 w1_gpio_set_pullup(void *data, int delay)
> +{
> + struct w1_gpio_platform_data *pdata = data;
> +
> + if (delay) {
> + pdata->pullup_duration = delay;
> + } else {
> + if (pdata->pullup_duration) {
> + gpio_direction_output(pdata->pin, 1);
> +
> + msleep(pdata->pullup_duration);

This doesn't look like a good idea - kernel will sleep for that long not doing usual w1 job

> --- a/drivers/w1/w1_int.c
> +++ b/drivers/w1/w1_int.c
> @@ -117,18 +117,6 @@ int w1_add_master_device(struct w1_bus_master *master)
>                 printk(KERN_ERR "w1_add_master_device: invalid function set\n");
>                 return(-EINVAL);
>          }
> - /* While it would be electrically possible to make a device that
> - * generated a strong pullup in bit bang mode, only hardware that
> - * controls 1-wire time frames are even expected to support a strong
> - * pullup.  w1_io.c would need to support calling set_pullup before
> - * the last write_bit operation of a w1_write_8 which it currently
> - * doesn't.
> - */
> - if (!master->write_byte && !master->touch_bit && master->set_pullup) {
> - printk(KERN_ERR "w1_add_master_device: set_pullup requires "
> - "write_byte or touch_bit, disabling\n");
> - master->set_pullup = NULL;
> - }
>

Why did you drop this check? It has nothing with w1-gpio driver