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Message-ID: <ac75aeff-1fca-f46f-1043-8437ef845ff9@189.cn>
Date: Thu, 24 Mar 2022 09:48:19 +0800
From: Sui Jingfeng <15330273260@....cn>
To: Rob Herring <robh@...nel.org>
Cc: Maxime Ripard <mripard@...nel.org>,
Thomas Zimmermann <tzimmermann@...e.de>,
Roland Scheidegger <sroland@...are.com>,
Zack Rusin <zackr@...are.com>,
Christian Gmeiner <christian.gmeiner@...il.com>,
David Airlie <airlied@...ux.ie>,
Daniel Vetter <daniel@...ll.ch>,
Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
Dan Carpenter <dan.carpenter@...cle.com>,
Krzysztof Kozlowski <krzk@...nel.org>,
Andrey Zhizhikin <andrey.zhizhikin@...ca-geosystems.com>,
Sam Ravnborg <sam@...nborg.org>,
"David S . Miller" <davem@...emloft.net>,
Jiaxun Yang <jiaxun.yang@...goat.com>,
Lucas Stach <l.stach@...gutronix.de>,
Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Ilia Mirkin <imirkin@...m.mit.edu>,
Qing Zhang <zhangqing@...ngson.cn>,
suijingfeng <suijingfeng@...ngson.cn>,
linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org,
devicetree@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH v11 5/7] dt-bindings: display: Add Loongson display
controller
On 2022/3/23 21:03, Rob Herring wrote:
> On Wed, Mar 23, 2022 at 11:38:55AM +0800, Sui Jingfeng wrote:
>> On 2022/3/23 04:55, Rob Herring wrote:
>>> On Tue, Mar 22, 2022 at 10:33:45AM +0800, Sui Jingfeng wrote:
>>>> On 2022/3/22 07:20, Rob Herring wrote:
>>>>> On Tue, Mar 22, 2022 at 12:29:14AM +0800, Sui Jingfeng wrote:
>>>>>> From: suijingfeng <suijingfeng@...ngson.cn>
>>>>>>
>>>>> Needs a commit message.
>>>>>
>>>>>> Signed-off-by: suijingfeng <suijingfeng@...ngson.cn>
>>>>>> Signed-off-by: Sui Jingfeng <15330273260@....cn>
>>>>> Same person? Don't need both emails.
>>>> Yes, suijingfeng@...ngson.cn is my company's email. But it can not be used
>>>> to send patches to dri-devel,
>>>>
>>>> when send patches with this email, the patch will not be shown on patch
>>>> works.
>>>>
>>>> Emails are either blocked or got rejected by loongson's mail server. It
>>>> can only receive emails
>>>>
>>>> from you and other people, but not dri-devel. so have to use my personal
>>>> email(15330273260@....cn) to send patches.
>>>>
>>>>>> ---
>>>>>> .../loongson/loongson,display-controller.yaml | 230 ++++++++++++++++++
>>>>>> 1 file changed, 230 insertions(+)
>>>>>> create mode 100644 Documentation/devicetree/bindings/display/loongson/loongson,display-controller.yaml
>>>>>>
>>>>>> diff --git a/Documentation/devicetree/bindings/display/loongson/loongson,display-controller.yaml b/Documentation/devicetree/bindings/display/loongson/loongson,display-controller.yaml
>>>>>> new file mode 100644
>>>>>> index 000000000000..7be63346289e
>>>>>> --- /dev/null
>>>>>> +++ b/Documentation/devicetree/bindings/display/loongson/loongson,display-controller.yaml
>>>>>> @@ -0,0 +1,230 @@
>>>>>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>>>>>> +%YAML 1.2
>>>>>> +---
>>>>>> +$id: http://devicetree.org/schemas/display/loongson/loongson,display-controller.yaml#
>>>>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>>>>> +
>>>>>> +title: Loongson LS7A1000/LS2K1000/LS2K0500 Display Controller Device Tree Bindings
>>>>>> +
>>>>>> +maintainers:
>>>>>> + - Sui Jingfeng <suijingfeng@...ngson.cn>
>>>>>> +
>>>>>> +description: |+
>>>>>> +
>>>>>> + Loongson display controllers are simple which require scanout buffers
>>>>>> + to be physically contiguous. LS2K1000/LS2K0500 is a SOC, only system
>>>>>> + memory is available. LS7A1000/LS7A2000 is bridge chip which is equipped
>>>>>> + with a dedicated video RAM which is 64MB or more, precise size can be
>>>>>> + read from the PCI BAR 2 of the GPU device(0x0014:0x7A15) in the bridge
>>>>>> + chip.
>>>>>> +
>>>>>> + LSDC has two display pipes, each way has a DVO interface which provide
>>>>>> + RGB888 signals, vertical & horizontal synchronisations, data enable and
>>>>>> + the pixel clock. LSDC has two CRTC, each CRTC is able to scanout from
>>>>>> + 1920x1080 resolution at 60Hz. Each CRTC has two FB address registers.
>>>>>> +
>>>>>> + For LS7A1000, there are 4 dedicated GPIOs whose control register is
>>>>>> + located at the DC register space. They are used to emulate two way i2c,
>>>>>> + One for DVO0, another for DVO1.
>>>>>> +
>>>>>> + LS2K1000 and LS2K0500 SoC grab i2c adapter from other module, either
>>>>>> + general purpose GPIO emulated i2c or hardware i2c in the SoC.
>>>>>> +
>>>>>> + LSDC's display pipeline have several components as below description,
>>>>>> +
>>>>>> + The display controller in LS7A1000:
>>>>>> + ___________________ _________
>>>>>> + | -------| | |
>>>>>> + | CRTC0 --> | DVO0 ----> Encoder0 ---> Connector0 ---> | Monitor |
>>>>>> + | _ _ -------| ^ ^ |_________|
>>>>>> + | | | | | -------| | |
>>>>>> + | |_| |_| | i2c0 <--------+-------------+
>>>>>> + | -------|
>>>>>> + | DC IN LS7A1000 |
>>>>>> + | _ _ -------|
>>>>>> + | | | | | | i2c1 <--------+-------------+
>>>>>> + | |_| |_| -------| | | _________
>>>>>> + | -------| | | | |
>>>>>> + | CRTC1 --> | DVO1 ----> Encoder1 ---> Connector1 ---> | Panel |
>>>>>> + | -------| |_________|
>>>>>> + |___________________|
>>>>>> +
>>>>>> + Simple usage of LS7A1000 with LS3A4000 CPU:
>>>>>> +
>>>>>> + +------+ +-----------------------------------+
>>>>>> + | DDR4 | | +-------------------+ |
>>>>>> + +------+ | | PCIe Root complex | LS7A1000 |
>>>>>> + || MC0 | +--++---------++----+ |
>>>>>> + +----------+ HT 3.0 | || || |
>>>>>> + | LS3A4000 |<-------->| +---++---+ +--++--+ +---------+ +------+
>>>>>> + | CPU |<-------->| | GC1000 | | LSDC |<-->| DDR3 MC |<->| VRAM |
>>>>>> + +----------+ | +--------+ +-+--+-+ +---------+ +------+
>>>>>> + || MC1 +---------------|--|----------------+
>>>>>> + +------+ | |
>>>>>> + | DDR4 | +-------+ DVO0 | | DVO1 +------+
>>>>>> + +------+ VGA <--|ADV7125|<--------+ +-------->|TFP410|--> DVI/HDMI
>>>>>> + +-------+ +------+
>>>>>> +
>>>>>> + The display controller in LS2K1000/LS2K0500:
>>>>>> + ___________________ _________
>>>>>> + | -------| | |
>>>>>> + | CRTC0 --> | DVO0 ----> Encoder0 ---> Connector0 ---> | Monitor |
>>>>>> + | _ _ -------| ^ ^ |_________|
>>>>>> + | | | | | | | |
>>>>>> + | |_| |_| | +------+ |
>>>>>> + | <---->| i2c0 |<---------+
>>>>>> + | DC IN LS2K1000 | +------+
>>>>>> + | _ _ | +------+
>>>>>> + | | | | | <---->| i2c1 |----------+
>>>>>> + | |_| |_| | +------+ | _________
>>>>>> + | -------| | | | |
>>>>>> + | CRTC1 --> | DVO1 ----> Encoder1 ---> Connector1 ---> | Panel |
>>>>>> + | -------| |_________|
>>>>>> + |___________________|
>>>>>> +
>>>>>> +properties:
>>>>>> + $nodename:
>>>>>> + pattern: "^display-controller@[0-9a-f],[0-9a-f]$"
>>>>>> +
>>>>>> + compatible:
>>>>>> + oneOf:
>>>>>> + - items:
>>>>>> + - enum:
>>>>>> + - loongson,ls7a1000-dc
>>>>>> + - loongson,ls2k1000-dc
>>>>>> + - loongson,ls2k0500-dc
>>>>>> +
>>>>>> + reg:
>>>>>> + maxItems: 1
>>>>>> +
>>>>>> + interrupts:
>>>>>> + maxItems: 1
>>>>>> +
>>>>>> + '#address-cells':
>>>>>> + const: 1
>>>>>> +
>>>>>> + '#size-cells':
>>>>>> + const: 0
>>>>>> +
>>>>>> + i2c-gpio@0:
>>>>>> + description: |
>>>>>> + Built-in GPIO emulate i2c exported for external display bridge
>>>>> If you have i2c-gpio, that belongs at the DT top-level, not here.
>>>>>
>>>>>> + configuration, onitor detection and edid read back etc, for ls7a1000
>>>>>> + only. Its compatible must be lsdc,i2c-gpio-0. The reg property can be
>>>>> No, there's a defined i2c-gpio compatible already.
>>>> This is different from the i2c-gpio already defined under drivers/i2c/busses/i2c-gpio.c,
>>>> By design, my i2c-gpio is vendor specific properties, lsdc device driver create the i2c
>>>> adapter at runtime. These are 4 dedicated GPIOs whose control register is located at the
>>>> LSDC register space, not general purpose GPIOs with separate control register resource.
>>>> So i think it is the child node of display-controller@6,1, it belongs to LSDC.
>>>> It seems that put it at the DT top-level break the hierarchy and relationship.
>>> Okay, I see. Then just 'i2c' for the node names. You need a reference to
>>> i2c-controller.yaml for these nodes too.
>>>
>>> The compatible should not have an index in it.
>> OK, i will fix this at the next version. thanks.
>>>>>> + used to specify a I2c adapter bus number, if you don't specify one
>>>>>> + i2c driver core will dynamically assign a bus number. Please specify
>>>>> Bus numbers are a linux detail not relevant to DT binding.
>>>>>
>>>>>> + it only when its bus number matters. Bus number greater than 6 is safe
>>>>>> + because ls7a1000 bridge have 6 hardware I2C controller integrated.
>>>>>> +
>>>>>> + i2c-gpio@1:
>>>>>> + description: |
>>>>>> + Built-in GPIO emulate i2c exported for external display bridge
>>>>>> + configuration, onitor detection and edid read back etc, for ls7a1000
>>>>>> + only. Its compatible must be lsdc,i2c-gpio-1.
>>>>>> +
>>>>>> + ports:
>>>>>> + $ref: /schemas/graph.yaml#/properties/ports
>>>>>> +
>>>>>> + properties:
>>>>>> + port@0:
>>>>>> + $ref: /schemas/graph.yaml#/properties/port
>>>>>> + description: output port node connected with DPI panels or external encoders, with only one endpoint.
>>>>>> +
>>>>>> + port@1:
>>>>>> + $ref: /schemas/graph.yaml#/properties/port
>>>>>> + description: output port node connected with DPI panels or external encoders, with only one endpoint.
>>>>>> +
>>>>>> + required:
>>>>>> + - port@0
>>>>>> + - port@1
>>>>>> +
>>>>>> +required:
>>>>>> + - compatible
>>>>>> + - reg
>>>>>> + - interrupts
>>>>>> + - ports
>>>>>> +
>>>>>> +additionalProperties: false
>>>>>> +
>>>>>> +examples:
>>>>>> + - |
>>>>>> + #include <dt-bindings/interrupt-controller/irq.h>
>>>>>> + bus {
>>>>>> +
>>>>>> + #address-cells = <3>;
>>>>>> + #size-cells = <2>;
>>>>>> + #interrupt-cells = <2>;
>>>>>> +
>>>>>> + display-controller@6,1 {
>>>>>> + compatible = "loongson,ls7a1000-dc";
>>>>>> + reg = <0x3100 0x0 0x0 0x0 0x0>;
>>>>>> + interrupts = <28 IRQ_TYPE_LEVEL_HIGH>;
>>>>>> +
>>>>>> + #address-cells = <1>;
>>>>>> + #size-cells = <0>;
>>>>>> +
>>>>>> + i2c-gpio@0 {
>>>>>> + compatible = "lsdc,i2c-gpio-0";
>>>>>> + reg = <6>;
>>> 'reg' needs to be documented with some description of what 6 and 7
>>> represent. If they are the control register offset, then make the
>>> address translatable (use 'ranges' and define the size).
>> By design, the reg property is used to specify a I2c adapter bus number,
>> if we don't specify one, i2c driver core will dynamically assign a bus number.
>> then the nr of the i2c adapter will started from 0. I want is start from 6
>> to avoid potential conflict feature hardware I2C driver.
>>
>> Because LS7A1000 bridge chip have 6 hardware I2C controller integrated,
>> but its driver is not up-streamed yet. By default these hardware I2C controller's
>> nr is started from 0.
> Linux's numbering doesn't belong in DT. So no, you can't use 'reg' in
> that way.
Then, can i use something like lsdc,nr = <6> ?
>> Even through i2c driver core can dynamically generate a number, i still want it
>> to be fixed and keep consistent and explicit. That is, i2c6 is for display pipe 0,
>> i2c7 is for display pipe 1. This follow the convention and flexible enough.
> You may want that, but that is not how the kernel works. Specific
> numbers are not guaranteed. I'm sure you've seen this for disks, network
> interfaces, etc.
>
> Rob
2c_bit_add_numbered_bus() will guarantee it for you as long as If no
devices have pre-been declared for this bus.
you can read the comment of 2c_bit_add_numbered_bus() at
drivers/i2c/i2c-core-base.c
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