From: Tomasz Figa <tfiga@chromium.org>
To: Sakari Ailus <sakari.ailus@linux.intel.com>
Cc: "Mark Rutland" <mark.rutland@arm.com>,
"Nicolas Boichat" <drinkcat@chromium.org>,
"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
srv_heupstream <srv_heupstream@mediatek.com>,
linux-devicetree <devicetree@vger.kernel.org>,
"Linus Walleij" <linus.walleij@linaro.org>,
"Shengnan Wang (王圣男)" <shengnan.wang@mediatek.com>,
"Bartosz Golaszewski" <bgolaszewski@baylibre.com>,
"Sj Huang" <sj.huang@mediatek.com>,
"Rob Herring" <robh+dt@kernel.org>,
"moderated list:ARM/Mediatek SoC support"
<linux-mediatek@lists.infradead.org>,
"Dongchun Zhu" <dongchun.zhu@mediatek.com>,
"Louis Kuo" <louis.kuo@mediatek.com>,
"Matthias Brugger" <matthias.bgg@gmail.com>,
"Cao Bing Bu" <bingbu.cao@intel.com>,
matrix.zhu@aliyun.com,
"Mauro Carvalho Chehab" <mchehab@kernel.org>,
"list@263.net:IOMMU DRIVERS <iommu@lists.linux-foundation.org>,
Joerg Roedel <joro@8bytes.org>,
" <linux-arm-kernel@lists.infradead.org>,
"Linux Media Mailing List" <linux-media@vger.kernel.org>
Subject: Re: [V7, 1/2] media: dt-bindings: media: i2c: Document OV02A10 bindings
Date: Thu, 7 May 2020 16:25:01 +0200 [thread overview]
Message-ID: <CAAFQd5DgDk57MCc4vE9VmifZYjtO_SUFss+vc8W-28SFHbKDrA@mail.gmail.com> (raw)
In-Reply-To: <20200507141147.GF9190@paasikivi.fi.intel.com>
On Thu, May 7, 2020 at 4:12 PM Sakari Ailus
<sakari.ailus@linux.intel.com> wrote:
>
> Hi Tomasz, Dongchun,
>
> On Thu, May 07, 2020 at 03:50:40PM +0200, Tomasz Figa wrote:
> > Hi Sakari and Dongchun,
> >
> > On Thu, May 7, 2020 at 3:00 PM Dongchun Zhu <dongchun.zhu@mediatek.com> wrote:
> > >
> > > Hi Sakari,
> > >
> > > Thanks for the review.
> > >
> > > On Wed, 2020-05-06 at 14:21 +0300, Sakari Ailus wrote:
> > > > Hi Dongchun,
> > > >
> > > > On Tue, May 05, 2020 at 10:17:18PM +0800, Dongchun Zhu wrote:
> > > > > Hi Sakari,
> > > > >
> > > > > Thanks for the review.
> > > > >
> > > > > On Tue, 2020-05-05 at 10:04 +0300, Sakari Ailus wrote:
> > > > > > Hi Dongchun,
> > > > > >
> > > > > > On Thu, Apr 30, 2020 at 04:09:23PM +0800, Dongchun Zhu wrote:
> > > > > > > Add DT bindings documentation for Omnivision OV02A10 image sensor.
> > > > > > >
> > > > > > > Signed-off-by: Dongchun Zhu <dongchun.zhu@mediatek.com>
> > > > > > > ---
> > > > > > > .../bindings/media/i2c/ovti,ov02a10.yaml | 148 +++++++++++++++++++++
> > > > > > > MAINTAINERS | 7 +
> > > > > > > 2 files changed, 155 insertions(+)
> > > > > > > create mode 100644 Documentation/devicetree/bindings/media/i2c/ovti,ov02a10.yaml
> > > > > > >
> > > > > > > diff --git a/Documentation/devicetree/bindings/media/i2c/ovti,ov02a10.yaml b/Documentation/devicetree/bindings/media/i2c/ovti,ov02a10.yaml
> > > > > > > new file mode 100644
> > > > > > > index 0000000..2be4bd2
> > > > > > > --- /dev/null
> > > > > > > +++ b/Documentation/devicetree/bindings/media/i2c/ovti,ov02a10.yaml
> > > > > > > @@ -0,0 +1,148 @@
> > > > > > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > > > > > > +# Copyright (c) 2020 MediaTek Inc.
> > > > > > > +%YAML 1.2
> > > > > > > +---
> > > > > > > +$id: http://devicetree.org/schemas/media/i2c/ovti,ov02a10.yaml#
> > > > > > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > > > > > +
> > > > > > > +title: Omnivision OV02A10 CMOS Sensor Device Tree Bindings
> > > > > > > +
> > > > > > > +maintainers:
> > > > > > > + - Dongchun Zhu <dongchun.zhu@mediatek.com>
> > > > > > > +
> > > > > > > +description: |-
> > > > > > > + The Omnivision OV02A10 is a low-cost, high performance, 1/5-inch, 2 megapixel
> > > > > > > + image sensor, which is the latest production derived from Omnivision's CMOS
> > > > > > > + image sensor technology. Ihis chip supports high frame rate speeds up to 30fps
> > > > > > > + @ 1600x1200 (UXGA) resolution transferred over a 1-lane MIPI interface. The
> > > > > > > + sensor output is available via CSI-2 serial data output.
> > > > > > > +
> > > > > > > +properties:
> > > > > > > + compatible:
> > > > > > > + const: ovti,ov02a10
> > > > > > > +
> > > > > > > + reg:
> > > > > > > + maxItems: 1
> > > > > > > +
> > > > > > > + clocks:
> > > > > > > + items:
> > > > > > > + - description: top mux camtg clock
> > > > > > > + - description: devider clock
> > > > > > > +
> > > > > > > + clock-names:
> > > > > > > + items:
> > > > > > > + - const: eclk
> > > > > > > + - const: freq_mux
> > > > > > > +
> > > > > > > + clock-frequency:
> > > > > > > + description:
> > > > > > > + Frequency of the eclk clock in Hertz.
> > > > > > > +
> > > > > > > + dovdd-supply:
> > > > > > > + description:
> > > > > > > + Definition of the regulator used as interface power supply.
> > > > > > > +
> > > > > > > + avdd-supply:
> > > > > > > + description:
> > > > > > > + Definition of the regulator used as analog power supply.
> > > > > > > +
> > > > > > > + dvdd-supply:
> > > > > > > + description:
> > > > > > > + Definition of the regulator used as digital power supply.
> > > > > > > +
> > > > > > > + powerdown-gpios:
> > > > > > > + description:
> > > > > > > + The phandle and specifier for the GPIO that controls sensor powerdown.
> > > > > > > +
> > > > > > > + reset-gpios:
> > > > > > > + description:
> > > > > > > + The phandle and specifier for the GPIO that controls sensor reset.
> > > > > > > +
> > > > > > > + rotation:
> > > > > > > + description:
> > > > > > > + Definition of the sensor's placement, valid values are 0 and 180.
> > > > > > > + allOf:
> > > > > > > + - $ref: "/schemas/types.yaml#/definitions/uint32"
> > > > > > > + - enum:
> > > > > > > + - 0 # Sensor Mounted Upright
> > > > > > > + - 180 # Sensor Mounted Upside Down
> > > > > > > +
> > > > > > > + ovti,mipi-tx-speed:
> > > > > > > + description:
> > > > > > > + Indication of MIPI transmission speed select.
> > > > > >
> > > > > > What exactly does this signify? And how do you come up with the number?
> > > > > >
> > > > >
> > > > > Apologies for not addressing this number clear.
> > > > >
> > > > > From the datasheet, P1:0xA1 register represents TX_SPEED_AREA_SEL with
> > > > > the default val: 0x03.
> > > > > The description of this RW register is as below:
> > > > > Bit[2:0]: MIPI transmission speed select.
> > > > >
> > > > > Thus the enum should be definited as [ 0, 1, 2, 3, 4, 5, 6, 7 ].
> > > > > This would be fixed in next release.
> > > > >
> > > > > In the meantime, as the default val of P1:0xA1 is 0x03, we hope to keep
> > > > > that value if there is no setting for this private property in DT.
> > > > > The caller in driver would be updated like this in next release.
> > > > > if (ov02a10->mipi_clock_tx_speed)
> > > > > ret = i2c_smbus_write_byte_data(...,...);
> > > >
> > > > How did you pick the value in the example? And why do you believe it is
> > > > specific to a platform, and not e.g. a sensor mode?
> > > >
> > >
> > > We look into P1:0XA1, one register that defines MIPI transmission speed
> > > select.
> > > From the datasheet, we can get the possible values that could be set to
> > > P1:0xA1.
> > >
> > > Actually this register is an independent of sensor mode, it is just
> > > included in sensor mode's register setting table.
> > >
> > > In addition, this private DT Property is created to fix the MIPI test
> > > failure. The register values are adjusted and verified from vendor to
> > > make sensor signal meet MIPI specification.
> > >
> >
> > In theory the value could depend on the mode, because different link
> > rate could impose different requirements for the physical interface.
> > In practice, we haven't seen any hardware that would require different
> > values for different modes.
>
> The mode (possibly in conjunction with other information available to the
> driver via V4L2 fwnode interface) precisely defines the parameters of the
> CSI-2 bus --- apart from the possible exception of the bus timing related
> parameters but this is not supported by the name of the parameter.
>
> Therefore I don't see how this parameter, which supposedly is used to
> determine the CSI-2 transmissions speed, could be board specific and thus
> belong to DT.
According to the very imprecise information I have access to, it is
not about the CSI-2 bus itself, but rather some internal parameter of
the sensor's CSI interface. Unfortunately there isn't much information
on what this value exactly controls...
Best regards,
Tomasz
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next prev parent reply other threads:[~2020-05-07 14:25 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-30 8:09 [V7, 0/2] media: i2c: Add support for OV02A10 sensor Dongchun Zhu
2020-04-30 8:09 ` [V7, 1/2] media: dt-bindings: media: i2c: Document OV02A10 bindings Dongchun Zhu
2020-05-05 7:04 ` Sakari Ailus
2020-05-05 14:17 ` Dongchun Zhu
2020-05-06 11:21 ` Sakari Ailus
2020-05-07 12:58 ` Dongchun Zhu
2020-05-07 13:50 ` Tomasz Figa
2020-05-07 14:11 ` Sakari Ailus
2020-05-07 14:25 ` Tomasz Figa [this message]
2020-05-08 6:51 ` Dongchun Zhu
2020-05-10 22:35 ` Sakari Ailus
2020-05-11 11:41 ` Dongchun Zhu
2020-07-15 14:01 ` Sakari Ailus
2020-07-16 14:57 ` Tomasz Figa
2020-07-20 2:30 ` Dongchun Zhu
2020-08-25 1:53 ` Dongchun Zhu
2020-05-05 16:15 ` Rob Herring
2020-05-07 13:02 ` Dongchun Zhu
2020-04-30 8:09 ` [V7, 2/2] media: i2c: ov02a10: Add OV02A10 image sensor driver Dongchun Zhu
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