From: Alejandro Tafalla <atafalla@dnyon.com> To: "Péter Ujfalusi" <peter.ujfalusi@linux.intel.com> Cc: Liam Girdwood <lgirdwood@gmail.com>, Mark Brown <broonie@kernel.org>, Andy Shevchenko <andy.shevchenko@gmail.com>, devicetree@vger.kernel.org, alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org, Takashi Iwai <tiwai@suse.com>, Rob Herring <robh+dt@kernel.org> Subject: Re: [PATCH v3 1/2] ASoC: max98927: Handle reset gpio when probing i2c Date: Sat, 04 Sep 2021 01:22:26 +0200 [thread overview] Message-ID: <5503823.DvuYhMxLoT@alexpc> (raw) In-Reply-To: <80973391-4579-e14b-6def-ed81f367a4a5@linux.intel.com> On 3/9/21 11:20 Péter Ujfalusi wrote: > > If this is a 'reset' pin then it's ACTIVE state is when it places the > device to _reset_. > GPIOD_OUT_LOW == Deasserted state of the GPIO line. > > If the reset pin should be pulled low for reset (GPIO_ACTIVE_LOW) and > you want the device initially in reset then you need GPIOD_OUT_HIGH, > because: > GPIOD_OUT_HIGH == Asserted state of the GPIO line. > > Same goes for the gpiod_set_value_cansleep(): > 0 - deasserted > 1 = asserted > > and this all depends on how the gpio is defined in DT > (GPIO_ACTIVE_LOW/HIGH), which depends on how the documentation refers to > the pin... > > reset pin: > low to keep the device in reset, high to release it from reset: > GPIO_ACTIVE_LOW > gpiod_set_value_cansleep(0) to enable > gpiod_set_value_cansleep(1) to disable > > > enable pin: > high to enable the part, low to disable > GPIO_ACTIVE_HIGH > gpiod_set_value_cansleep(1) to enable > gpiod_set_value_cansleep(0) to disable > > In both cases > electrical 0: reset/disable > electrical 1: enable I'll change it to be consistent in the next version. Thank you for the explanation. > > + if (IS_ERR(reset_gpio)) { > > + ret = PTR_ERR(reset_gpio); > > + return dev_err_probe(&i2c->dev, ret, "failed to request GPIO reset > > pin"); + } > > + > > + if (reset_gpio) { > > + usleep_range(8000, 10000); > > + gpiod_set_value_cansleep(reset_gpio, 1); > > + usleep_range(1000, 5000); > > + } > > + > > You might want to put the device to reset on remove at minimum. Okay, thanks. -- Alejandro Tafalla
WARNING: multiple messages have this Message-ID (diff)
From: Alejandro Tafalla <atafalla@dnyon.com> To: "Péter Ujfalusi" <peter.ujfalusi@linux.intel.com> Cc: devicetree@vger.kernel.org, alsa-devel@alsa-project.org, Takashi Iwai <tiwai@suse.com>, Liam Girdwood <lgirdwood@gmail.com>, Rob Herring <robh+dt@kernel.org>, linux-kernel@vger.kernel.org, Andy Shevchenko <andy.shevchenko@gmail.com>, Mark Brown <broonie@kernel.org> Subject: Re: [PATCH v3 1/2] ASoC: max98927: Handle reset gpio when probing i2c Date: Sat, 04 Sep 2021 01:22:26 +0200 [thread overview] Message-ID: <5503823.DvuYhMxLoT@alexpc> (raw) In-Reply-To: <80973391-4579-e14b-6def-ed81f367a4a5@linux.intel.com> On 3/9/21 11:20 Péter Ujfalusi wrote: > > If this is a 'reset' pin then it's ACTIVE state is when it places the > device to _reset_. > GPIOD_OUT_LOW == Deasserted state of the GPIO line. > > If the reset pin should be pulled low for reset (GPIO_ACTIVE_LOW) and > you want the device initially in reset then you need GPIOD_OUT_HIGH, > because: > GPIOD_OUT_HIGH == Asserted state of the GPIO line. > > Same goes for the gpiod_set_value_cansleep(): > 0 - deasserted > 1 = asserted > > and this all depends on how the gpio is defined in DT > (GPIO_ACTIVE_LOW/HIGH), which depends on how the documentation refers to > the pin... > > reset pin: > low to keep the device in reset, high to release it from reset: > GPIO_ACTIVE_LOW > gpiod_set_value_cansleep(0) to enable > gpiod_set_value_cansleep(1) to disable > > > enable pin: > high to enable the part, low to disable > GPIO_ACTIVE_HIGH > gpiod_set_value_cansleep(1) to enable > gpiod_set_value_cansleep(0) to disable > > In both cases > electrical 0: reset/disable > electrical 1: enable I'll change it to be consistent in the next version. Thank you for the explanation. > > + if (IS_ERR(reset_gpio)) { > > + ret = PTR_ERR(reset_gpio); > > + return dev_err_probe(&i2c->dev, ret, "failed to request GPIO reset > > pin"); + } > > + > > + if (reset_gpio) { > > + usleep_range(8000, 10000); > > + gpiod_set_value_cansleep(reset_gpio, 1); > > + usleep_range(1000, 5000); > > + } > > + > > You might want to put the device to reset on remove at minimum. Okay, thanks. -- Alejandro Tafalla
next prev parent reply other threads:[~2021-09-03 23:22 UTC|newest] Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-09-03 1:49 [PATCH v3 0/2] Add reset-gpios handling for max98927 Alejandro 2021-09-03 1:49 ` Alejandro 2021-09-03 1:49 ` [PATCH v3 1/2] ASoC: max98927: Handle reset gpio when probing i2c Alejandro 2021-09-03 1:49 ` Alejandro 2021-09-03 8:18 ` Andy Shevchenko 2021-09-03 8:18 ` Andy Shevchenko 2021-09-03 15:52 ` Alejandro Tafalla 2021-09-03 15:52 ` Alejandro Tafalla 2021-09-03 9:20 ` Péter Ujfalusi 2021-09-03 9:20 ` Péter Ujfalusi 2021-09-03 23:22 ` Alejandro Tafalla [this message] 2021-09-03 23:22 ` Alejandro Tafalla 2021-09-03 1:49 ` [PATCH v3 2/2] dt-bindings: sound: max98927: Add reset-gpios optional property Alejandro 2021-09-03 1:49 ` Alejandro 2021-09-03 17:41 ` Rob Herring 2021-09-03 17:41 ` Rob Herring 2021-09-03 17:58 ` Alejandro Tafalla 2021-09-03 17:58 ` Alejandro Tafalla 2021-09-03 8:16 ` [PATCH v3 0/2] Add reset-gpios handling for max98927 Andy Shevchenko 2021-09-03 8:16 ` Andy Shevchenko 2021-09-03 16:02 ` Alejandro Tafalla 2021-09-03 16:02 ` Alejandro Tafalla
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