diff options
Diffstat (limited to 'target/linux/generic/backport-4.14/085-v4.16-0001-i2c-gpio-Enable-working-over-slow-can_sleep-GPIOs.patch')
| -rw-r--r-- | target/linux/generic/backport-4.14/085-v4.16-0001-i2c-gpio-Enable-working-over-slow-can_sleep-GPIOs.patch | 84 |
1 files changed, 0 insertions, 84 deletions
diff --git a/target/linux/generic/backport-4.14/085-v4.16-0001-i2c-gpio-Enable-working-over-slow-can_sleep-GPIOs.patch b/target/linux/generic/backport-4.14/085-v4.16-0001-i2c-gpio-Enable-working-over-slow-can_sleep-GPIOs.patch deleted file mode 100644 index ead6675e0b..0000000000 --- a/target/linux/generic/backport-4.14/085-v4.16-0001-i2c-gpio-Enable-working-over-slow-can_sleep-GPIOs.patch +++ /dev/null @@ -1,84 +0,0 @@ -From f11a04464ae57e8db1bb7634547842b43e36a898 Mon Sep 17 00:00:00 2001 -From: =?UTF-8?q?Jan=20Kundr=C3=A1t?= <jan.kundrat@cesnet.cz> -Date: Fri, 22 Dec 2017 22:47:16 +0100 -Subject: i2c: gpio: Enable working over slow can_sleep GPIOs -MIME-Version: 1.0 -Content-Type: text/plain; charset=UTF-8 -Content-Transfer-Encoding: 8bit - -"Slow" GPIOs (usually those connected over an SPI or an I2C bus) are, -well, slow in their operation. It is generally a good idea to avoid -using them for time-critical operation, but sometimes the hardware just -sucks, and the software has to cope. In addition to that, the I2C bus -itself does not actually define any strict timing limits; the bus is -free to go all the way down to DC. The timeouts (and therefore the -slowest acceptable frequency) are present only in SMBus. - -The `can_sleep` is IMHO a wrong concept to use here. My SPI-to-quad-UART -chip (MAX14830) is connected via a 26MHz SPI bus, and it happily drives -SCL at 200kHz (5µs pulses) during my benchmarks. That's faster than the -maximal allowed speed of the traditional I2C. - -The previous version of this code did not really block operation over -slow GPIO pins, anyway. Instead, it just resorted to printing a warning -with a backtrace each time a GPIO pin was accessed, thereby slowing -things down even more. - -Finally, it's not just me. A similar patch was originally submitted in -2015 [1]. - -[1] https://patchwork.ozlabs.org/patch/450956/ - -Signed-off-by: Jan Kundrát <jan.kundrat@cesnet.cz> -Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> -Signed-off-by: Wolfram Sang <wsa@the-dreams.de> ---- - drivers/i2c/busses/i2c-gpio.c | 11 +++++++---- - 1 file changed, 7 insertions(+), 4 deletions(-) - ---- a/drivers/i2c/busses/i2c-gpio.c -+++ b/drivers/i2c/busses/i2c-gpio.c -@@ -44,7 +44,7 @@ static void i2c_gpio_setsda_val(void *da - { - struct i2c_gpio_platform_data *pdata = data; - -- gpio_set_value(pdata->sda_pin, state); -+ gpio_set_value_cansleep(pdata->sda_pin, state); - } - - /* Toggle SCL by changing the direction of the pin. */ -@@ -68,21 +68,21 @@ static void i2c_gpio_setscl_val(void *da - { - struct i2c_gpio_platform_data *pdata = data; - -- gpio_set_value(pdata->scl_pin, state); -+ gpio_set_value_cansleep(pdata->scl_pin, state); - } - - static int i2c_gpio_getsda(void *data) - { - struct i2c_gpio_platform_data *pdata = data; - -- return gpio_get_value(pdata->sda_pin); -+ return gpio_get_value_cansleep(pdata->sda_pin); - } - - static int i2c_gpio_getscl(void *data) - { - struct i2c_gpio_platform_data *pdata = data; - -- return gpio_get_value(pdata->scl_pin); -+ return gpio_get_value_cansleep(pdata->scl_pin); - } - - static int of_i2c_gpio_get_pins(struct device_node *np, -@@ -175,6 +175,9 @@ static int i2c_gpio_probe(struct platfor - memcpy(pdata, dev_get_platdata(&pdev->dev), sizeof(*pdata)); - } - -+ if (gpiod_cansleep(gpio_to_desc(pdata->sda_pin)) || gpiod_cansleep(gpio_to_desc(pdata->scl_pin))) -+ dev_warn(&pdev->dev, "Slow GPIO pins might wreak havoc into I2C/SMBus bus timing"); -+ - if (pdata->sda_is_open_drain) { - gpio_direction_output(pdata->sda_pin, 1); - bit_data->setsda = i2c_gpio_setsda_val; |