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X-IronPort-AV: E=McAfee;i="6600,9927,10990"; a="13267305" X-IronPort-AV: E=Sophos;i="6.06,175,1705392000"; d="scan'208";a="13267305" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmvoesa105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Feb 2024 23:43:42 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10990"; a="827300778" X-IronPort-AV: E=Sophos;i="6.06,175,1705392000"; d="scan'208";a="827300778" Received: from turnipsi.fi.intel.com (HELO kekkonen.fi.intel.com) ([10.237.72.44]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Feb 2024 23:43:34 -0800 Received: from kekkonen.localdomain (localhost [127.0.0.1]) by kekkonen.fi.intel.com (Postfix) with ESMTP id B6E6511F855; Wed, 21 Feb 2024 09:43:31 +0200 (EET) Date: Wed, 21 Feb 2024 07:43:31 +0000 From: "sakari.ailus@linux.intel.com" To: Zhi Mao =?utf-8?B?KOavm+aZuik=?= Cc: "heiko@sntech.de" , "linux-mediatek@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "yunkec@chromium.org" , "robh+dt@kernel.org" , "dan.scally@ideasonboard.com" , Shengnan Wang =?utf-8?B?KOeOi+Wco+eUtyk=?= , "hdegoede@redhat.com" , "linux-media@vger.kernel.org" , "gerald.loacker@wolfvision.net" , "linus.walleij@linaro.org" , "andy.shevchenko@gmail.com" , Yaya Chang =?utf-8?B?KOW8tembhea4hSk=?= , "jacopo.mondi@ideasonboard.com" , "mchehab@kernel.org" , "jernej.skrabec@gmail.com" , Project_Global_Chrome_Upstream_Group , "tomi.valkeinen@ideasonboard.com" , "10572168@qq.com" <10572168@qq.com>, "hverkuil-cisco@xs4all.nl" , "bingbu.cao@intel.com" , "krzysztof.kozlowski+dt@linaro.org" , "conor+dt@kernel.org" , "matthias.bgg@gmail.com" , "laurent.pinchart@ideasonboard.com" , "linux-arm-kernel@lists.infradead.org" , "angelogioacchino.delregno@collabora.com" , "devicetree@vger.kernel.org" , "macromorgan@hotmail.com" Subject: Re: [PATCH v4 2/2] media: i2c: Add GC08A3 image sensor driver Message-ID: References: <20240204061538.2105-1-zhi.mao@mediatek.com> <20240204061538.2105-3-zhi.mao@mediatek.com> <20240206184542.GE2827@pendragon.ideasonboard.com> <598f62bbb55157eec1e23dd1dbc307fea3851b21.camel@mediatek.com> <20240220030104.GF20376@pendragon.ideasonboard.com> <115698c0c549e747026cc8841a3bd571533f8e6f.camel@mediatek.com> <063fa9763efb1570295cfef385829714dd5e42cf.camel@mediatek.com> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <063fa9763efb1570295cfef385829714dd5e42cf.camel@mediatek.com> Hi Zhi, On Wed, Feb 21, 2024 at 02:37:27AM +0000, Zhi Mao (毛智) wrote: > Hi Laurent & sakari, > > Thanks for your feedback. > > On Tue, 2024-02-20 at 07:25 +0000, sakari.ailus@linux.intel.com wrote: > > > > External email : Please do not click links or open attachments until > > you have verified the sender or the content. > > Hi Zhi, > > > > On Tue, Feb 20, 2024 at 05:45:54AM +0000, Zhi Mao (毛智) wrote: > > > Hi Laurent, > > > > > > Thanks for you reply. > > > I'd like to ask for advice about how to contrl "reset-pin", please > > > check the below comments. > > > > > > On Tue, 2024-02-20 at 05:01 +0200, Laurent Pinchart wrote: > > > > > > > > External email : Please do not click links or open attachments > > until > > > > you have verified the sender or the content. > > > > Hi Zhi, > > > > > > > > On Tue, Feb 20, 2024 at 02:12:26AM +0000, Zhi Mao (毛智) wrote: > > > > > On Tue, 2024-02-06 at 20:45 +0200, Laurent Pinchart wrote: > > > > > > On Sun, Feb 04, 2024 at 02:15:38PM +0800, Zhi Mao wrote: > > > > > > > Add a V4L2 sub-device driver for Galaxycore GC08A3 image > > > > sensor. > > > > > > > > > > > > > > Signed-off-by: Zhi Mao > > > > > > > --- > > > > > > > drivers/media/i2c/Kconfig | 10 + > > > > > > > drivers/media/i2c/Makefile | 1 + > > > > > > > drivers/media/i2c/gc08a3.c | 1448 > > > > ++++++++++++++++++++++++++++++++++++ > > > > > > > 3 files changed, 1459 insertions(+) > > > > > > > create mode 100644 drivers/media/i2c/gc08a3.c > > > > > > > > [snip] > > > > > > > > > > > diff --git a/drivers/media/i2c/gc08a3.c > > > > b/drivers/media/i2c/gc08a3.c > > > > > > > new file mode 100644 > > > > > > > index 000000000000..3fc7fffb815c > > > > > > > --- /dev/null > > > > > > > +++ b/drivers/media/i2c/gc08a3.c > > > > > > > @@ -0,0 +1,1448 @@ > > > > > > > > [snip] > > > > > > > > > > > +static int gc08a3_power_on(struct device *dev) > > > > > > > +{ > > > > > > > +struct i2c_client *client = to_i2c_client(dev); > > > > > > > +struct v4l2_subdev *sd = i2c_get_clientdata(client); > > > > > > > +struct gc08a3 *gc08a3 = to_gc08a3(sd); > > > > > > > +int ret; > > > > > > > + > > > > > > > +ret = > > regulator_bulk_enable(ARRAY_SIZE(gc08a3_supply_name), > > > > > > > + gc08a3->supplies); > > > > > > > +if (ret < 0) { > > > > > > > +dev_err(gc08a3->dev, "failed to enable regulators: %d\n", > > > > ret); > > > > > > > +return ret; > > > > > > > +} > > > > > > > + > > > > > > > +ret = clk_prepare_enable(gc08a3->xclk); > > > > > > > +if (ret < 0) { > > > > > > > +regulator_bulk_disable(ARRAY_SIZE(gc08a3_supply_name), > > > > > > > + gc08a3->supplies); > > > > > > > +dev_err(gc08a3->dev, "clk prepare enable failed\n"); > > > > > > > +return ret; > > > > > > > +} > > > > > > > + > > > > > > > +usleep_range(GC08A3_MIN_SLEEP_US, GC08A3_MAX_SLEEP_US); > > > > > > > + > > > > > > > +gpiod_set_value_cansleep(gc08a3->reset_gpio, 1); > > > > > > > > > > > > Are you asserting reset when powering on ? That sounds wrong, > > you > > > > should > > > > > > de-assert reset here (and acquire the reset gpio in probe() > > with > > > > > > GPIOD_OUT_HIGH). Drivers should use logical levels for GPIOs, > > > > setting a > > > > > > GPIO named "reset" to 1 should assert the reset signal, even > > if > > > > the > > > > > > physical signal is active low. You may have the wrong > > polarity in > > > > the > > > > > > device tree. > > > > > > > > > > According to the sensor power sequence sepc, "reset" pin should > > be > > > > pull > > > > > from low to high after "dovdd/dvdd/avdd" power on, so I follow > > this > > > > > power sequece to pull "reset" pin high in software flow. > > > > > > > > From a hardware point of view that's right, but the Linux kernel > > > > handles > > > > logical level of GPIOs. If a GPIO is named "reset", it is > > expected > > > > that > > > > calling > > > > > > > > gpiod_set_value_cansleep(gc08a3->reset_gpio, 1); > > > > > > > > will "assert" the reset signal, setting it to a logical "reset = > > > > true" > > > > level. This maps to the hardware 0V output level, as the signal > > is > > > > active-low. To achieve this, define the reset GPIO as active low > > in > > > > DT, > > > > and the GPIO framework will invert the signal for you. You should > > > > then > > > > call > > > > > > > > gpiod_set_value_cansleep(gc08a3->reset_gpio, 1); > > > > > > > > in the driver when you want to assert reset (set it to 0V), and > > > > > > > > gpiod_set_value_cansleep(gc08a3->reset_gpio, 0); > > > > > > > > when you want to deassert it (set it to 3.3V, or whatever the I/O > > > > voltage for the signal is). > > > > > > > > This way all driver use logical states, and the inversion is > > handled > > > > in > > > > DT. > > > > > > > > > > Sensor power sequence as below: > > > ------------------ > > > | | | > > > | | | > > > dvdd/avdd/dovdd -------- > > > --------- > > > | > > > | > > > reset-pin ------------- > > > > > > In order to match this power sequece, "reset-pin" contrl flow is > > below: > > > 1. config the "reset-pin" is "active-high" in DTS: > > > reset-gpios = <&pio 19 GPIO_ACTIVE_HIGH>; > > > > > > 2. image sensor driver probe function: > > > gc08a3->reset_gpio = devm_gpiod_get(dev, "reset", > > > GPIOD_OUT_LOW); //init "reset-pin" is low > > > > > > 3. image sensor driver power_on function: > > > gpiod_set_value_cansleep(gc08a3->reset_gpio, 1); //pull "reset-pin" > > > high > > > > > > so, the expect state of "reset-pin" is from low to high. > > > If I am wrong, please correct me. > > > > > > From Documentation/driver-api/gpio/consumer.rst: > > > > As a consumer should not have to care about the physical line > > level, all of the gpiod_set_value_xxx() or > > gpiod_set_array_value_xxx() functions operate with the *logical* > > value. With this they take the active low property into account. > > This means that they check whether the GPIO is configured to be > > active low, and if so, they manipulate the passed value before the > > physical line level is driven. > > > > I.e. when you want to enable reset, you set the value to 1 in the > > driver. I > > think you're now setting the value to 0 in that case. The opposite > > for > > disabling it of course. > > > After checking "Documentation/driver-api/gpio/consumer.rst": > To summarize:: > Function (example) line property physical > line > ... > gpiod_set_value(desc, 1); default (active high) high > gpiod_set_value(desc, 0); active low high > ... > > > From my understanding, it seems that "reset-pin" is using the > following(active_high) case in current code: > "gpiod_set_value(desc, 1); default (active high) high" > > Do you mean, we should use the "active_low" case: > "gpiod_set_value(desc, 0); active low high" > Code should be changed as below: > 1. config the "reset-pin" is "active-low" in DTS: > - reset-gpios = <&pio 19 GPIO_ACTIVE_LOW> > 2. image sensor driver power_on function: > - gpiod_set_value_cansleep(gc08a3->reset_gpio, 0); //pull high > Is that so? Correct. -- Regards, Sakari Ailus