Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754452AbbHYAsS (ORCPT ); Mon, 24 Aug 2015 20:48:18 -0400 Received: from comal.ext.ti.com ([198.47.26.152]:58314 "EHLO comal.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751990AbbHYAsQ (ORCPT ); Mon, 24 Aug 2015 20:48:16 -0400 Message-ID: <55DBBB3F.6030205@ti.com> Date: Mon, 24 Aug 2015 19:47:59 -0500 From: "Franklin S Cooper Jr." User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.8.0 MIME-Version: 1.0 To: Dmitry Torokhov CC: , , , , , , , Subject: Re: [PATCH] Input: edt-ft5x06 - Switch to newer gpio framework References: <1440184112-11061-1-git-send-email-fcooper@ti.com> <20150824194113.GE22442@dtor-ws> <55DB7514.7030009@ti.com> <20150824200126.GF22442@dtor-ws> <55DB7BA4.5010905@ti.com> <55DB7D4F.4090004@ti.com> <20150824205624.GG22442@dtor-ws> <55DB97AF.5020905@ti.com> <20150825001755.GH22442@dtor-ws> In-Reply-To: <20150825001755.GH22442@dtor-ws> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8457 Lines: 171 On 08/24/2015 07:17 PM, Dmitry Torokhov wrote: > On Mon, Aug 24, 2015 at 05:16:15PM -0500, Franklin S Cooper Jr. wrote: >> >> On 08/24/2015 03:56 PM, Dmitry Torokhov wrote: >>> On Mon, Aug 24, 2015 at 03:23:43PM -0500, Franklin S Cooper Jr. wrote: >>>> On 08/24/2015 03:16 PM, Franklin S Cooper Jr. wrote: >>>>> On 08/24/2015 03:01 PM, Dmitry Torokhov wrote: >>>>>> On Mon, Aug 24, 2015 at 02:48:36PM -0500, Franklin S Cooper Jr. wrote: >>>>>>> On 08/24/2015 02:41 PM, Dmitry Torokhov wrote: >>>>>>>> On Fri, Aug 21, 2015 at 02:08:32PM -0500, Franklin S Cooper Jr wrote: >>>>>>>>> The current/old gpio framework used doesn't properly listen to >>>>>>>>> ACTIVE_LOW and ACTIVE_HIGH flags. The newer gpio framework takes into >>>>>>>>> account these flags when setting gpio values. >>>>>>>>> >>>>>>>>> Also use gpiod_set_value_cansleep since wake and reset pins can be >>>>>>>>> provided by bus based io expanders. >>>>>>>>> >>>>>>>>> Signed-off-by: Franklin S Cooper Jr >>>>>>>>> --- >>>>>>>>> .../bindings/input/touchscreen/edt-ft5x06.txt | 4 +- >>>>>>>>> drivers/input/touchscreen/edt-ft5x06.c | 115 +++++++-------------- >>>>>>>>> include/linux/input/edt-ft5x06.h | 4 +- >>>>>>>>> 3 files changed, 43 insertions(+), 80 deletions(-) >>>>>>>>> >>>>>>>>> diff --git a/Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.txt b/Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.txt >>>>>>>>> index 76db967..9330d4d 100644 >>>>>>>>> --- a/Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.txt >>>>>>>>> +++ b/Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.txt >>>>>>>>> @@ -50,6 +50,6 @@ Example: >>>>>>>>> pinctrl-0 = <&edt_ft5x06_pins>; >>>>>>>>> interrupt-parent = <&gpio2>; >>>>>>>>> interrupts = <5 0>; >>>>>>>>> - reset-gpios = <&gpio2 6 1>; >>>>>>>>> - wake-gpios = <&gpio4 9 0>; >>>>>>>>> + reset-gpios = <&gpio2 6 GPIO_ACTIVE_LOW>; >>>>>>>>> + wake-gpios = <&gpio4 9 GPIO_ACTIVE_HIGH>; >>>>>>>>> }; >>>>>>>>> diff --git a/drivers/input/touchscreen/edt-ft5x06.c b/drivers/input/touchscreen/edt-ft5x06.c >>>>>>>>> index 394b1de..6b128b3 100644 >>>>>>>>> --- a/drivers/input/touchscreen/edt-ft5x06.c >>>>>>>>> +++ b/drivers/input/touchscreen/edt-ft5x06.c >>>>>>>>> @@ -91,9 +91,9 @@ struct edt_ft5x06_ts_data { >>>>>>>>> u16 num_x; >>>>>>>>> u16 num_y; >>>>>>>>> >>>>>>>>> - int reset_pin; >>>>>>>>> - int irq_pin; >>>>>>>>> - int wake_pin; >>>>>>>>> + struct gpio_desc *reset_pin; >>>>>>>>> + struct gpio_desc *wake_pin; >>>>>>>>> + struct gpio_desc *irq_pin; >>>>>>>>> >>>>>>>>> #if defined(CONFIG_DEBUG_FS) >>>>>>>>> struct dentry *debug_dir; >>>>>>>>> @@ -755,36 +755,14 @@ edt_ft5x06_ts_teardown_debugfs(struct edt_ft5x06_ts_data *tsdata) >>>>>>>>> static int edt_ft5x06_ts_reset(struct i2c_client *client, >>>>>>>>> struct edt_ft5x06_ts_data *tsdata) >>>>>>>>> { >>>>>>>>> - int error; >>>>>>>>> - >>>>>>>>> - if (gpio_is_valid(tsdata->wake_pin)) { >>>>>>>>> - error = devm_gpio_request_one(&client->dev, >>>>>>>>> - tsdata->wake_pin, GPIOF_OUT_INIT_LOW, >>>>>>>>> - "edt-ft5x06 wake"); >>>>>>>>> - if (error) { >>>>>>>>> - dev_err(&client->dev, >>>>>>>>> - "Failed to request GPIO %d as wake pin, error %d\n", >>>>>>>>> - tsdata->wake_pin, error); >>>>>>>>> - return error; >>>>>>>>> - } >>>>>>>>> - >>>>>>>>> + if (tsdata->wake_pin) { >>>>>>>>> msleep(5); >>>>>>>>> - gpio_set_value(tsdata->wake_pin, 1); >>>>>>>>> + gpiod_set_value_cansleep(tsdata->wake_pin, 1); >>>>>>>>> } >>>>>>>>> - if (gpio_is_valid(tsdata->reset_pin)) { >>>>>>>>> - /* this pulls reset down, enabling the low active reset */ >>>>>>>>> - error = devm_gpio_request_one(&client->dev, >>>>>>>>> - tsdata->reset_pin, GPIOF_OUT_INIT_LOW, >>>>>>>>> - "edt-ft5x06 reset"); >>>>>>>>> - if (error) { >>>>>>>>> - dev_err(&client->dev, >>>>>>>>> - "Failed to request GPIO %d as reset pin, error %d\n", >>>>>>>>> - tsdata->reset_pin, error); >>>>>>>>> - return error; >>>>>>>>> - } >>>>>>>>> >>>>>>>>> + if (tsdata->reset_pin) { >>>>>>>>> msleep(5); >>>>>>>>> - gpio_set_value(tsdata->reset_pin, 1); >>>>>>>>> + gpiod_set_value_cansleep(tsdata->reset_pin, 1); >>>>>>>> So this leaves the reset pin active. How exactly was this tested? >>>>>>> Normally if the output gpio connected to the reset pin is ACTIVE_HIGH then this will take the tsc out of reset since >>>>>>> the reset pin is active low. However, I have a board that has an inverter between the gpio and reset pin. So if I leave >>>>>>> the gpio as ACTIVE_HIGH then the inverter would cause the reset pin to go low which will keep it in reset. So instead >>>>>>> I set the gpio to ACTIVE_LOW which gives me the expected result. >>>>>> I do not really care about particular board. Assuming that polarity of >>>>>> the GPIO in DTS is specified correctly the effect of: >>>>>> >>>>>> gpiod_set_value_cansleep(tsdata->reset_pin, 1); >>>>>> >>>>>> is reset pin being _active_, i.e. the chip is staying in reset state. >>>>> Setting the reset pin to 1/high will take the tsc out of reset. Setting the pin to 0/low will put the tsc into reset mode. >>> It seems you are not quite getting gpiod API. Consider: >>> >>> For gpios described as GPIO_ACTIVE_LOW: >>> >>> gpiod_set_value_cansleep(gpio, 1) => GPIO is LOW >>> gpiod_set_value_cansleep(gpio, 0) => GPIO is HIGH >>> >>> For gpios described as GPIO_ACTIVE_HIGH: >>> >>> gpiod_set_value_cansleep(gpio, 1) => GPIO is HIGH >>> gpiod_set_value_cansleep(gpio, 0) => GPIO is LOW >>> >>> IOW with gpiod API 1 means logical active and can be either HIGH or LOW, >>> depending on GPIO definition in DTS. >>> >>>>>> By the way, both reset and wake pins are active low according to the >>>>>> data sheet I found. >>>>> Your right. Reset and wake are both active low. However, that part of the code is trying to get the tsc out of reset which is >>>>> why its setting the value to 1. Setting the pin to 1 was being done even before my patch. >>>>> >>>>> What has changed was removing the below line which puts the tsc in reset. >>>>> >>>>> error = devm_gpio_request_one(&client->dev, tsdata->reset_pin, GPIOF_OUT_INIT_LOW,"edt-ft5x06 reset"); >>>>> >>>>> However, the above line isn't needed since when I request the gpio I already configured it as an output >>>>> with a default value of 0. >>> So the old sequence resulted in GPIO going XXX->0->1 which brought the >>> chip into reset and out of it. With the sequence you have, assuming >>> that the GPIO is described as GPIO_ACTIVE_LOW (to match data sheet), >> I'm not setting the GPIO_ACTIVE_LOW to match the datasheet. I'm setting it to ACTIVE_LOW because >> of the inverter that is between the gpio and reset pin makes it "appear" as if the gpio is ACTIVE_LOW. > If the "normal" behavior (according to the data sheet) is active low and > you have an invertor, then your DTS should be GPIO_ACTIVE_HIGH. And > people with hardware that does not have invertor will use > GPIO_ACTIVE_LOW. And the driver should work with both settings. > >>> we'll be getting XXX->1->0: >>> >>> devm_gpiod_get_optional(&client->dev, "reset", GPIOD_OUT_LOW) => >>> GPIO is *HIGH* >>> >>> gpiod_set_value_cansleep(gpio, 1) => GPIO is *LOW* >> So everything you stated is exactly what I wanted and expected when you take into account the inverter will invert the gpio signal before >> it reaches the reset pin. > I do not want to take into account invertor, that is what DTS polarity > flag for. Regular setup for this touchscreen - GPIO_ACTIVE_LOW, setup > with invertor - GPIO_ACTIVE_HIGH. From the driver perspective you should > be leaving the power on/reset function with reset and wake GPIOs > *inactive* (as in gpiod_set_value_cansleep(gpio, 0)). Ok. I was talking to someone about this and I believe I understand what your saying. So essentially the set_value call before my patch was based on voltage while the new gpio is based on logic. So the solution would be to change gpiod_set_value_cansleep to 0. Then my hardware inverted GPIO signal will be set to GPIO_ACTIVE_HIGH in dt. I can then tweak all the DTS files currently using this driver in mainline to reflect this change. > > Thanks. > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/