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smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=J6kx+VL8; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="J6kx+VL8" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C132EC4CEE7; Wed, 2 Jul 2025 15:02:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1751468537; bh=Ol5p1wzxA4/a7sOfr8ShQphBbuSDW4KTebkk5U0x49o=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=J6kx+VL8vrXI0hZoKqFO8JWMHZqVNvR4Vo1qPHtI1YTLMggNW8nIZdEivwAxE3QYg YsNshKAiIdu1PlZM2Sy27GgEQYKnORN4inpTo81fKUI7gTaeK0CWWEJnd+jdDlVChH yqtMmNvorl2n1lGms1ZP8FCTqrOFZtK6SvEAmLprORR8w+tPb1tA5Oo8fCwgYwDuIt odJiVPts18It7AeQeiMUQrcuFqtZeMhrtZEfv1uNLDtcjcsTwmwBnbGPlShj0VFlIw V7JOweaxlgLML7tY3Znx8O7Z4PxDNmVBiuFHXtrjPYB1ETz5Kb6jmw+RJIaJy85rlC i/VkHkJcqKtOQ== Message-ID: Date: Wed, 2 Jul 2025 17:02:11 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 6/8] dt-bindings: auxdisplay: add Titan Micro Electronics TM16XX To: =?UTF-8?Q?Jean-Fran=C3=A7ois_Lessard?= , Andy Shevchenko , Rob Herring , Krzysztof Kozlowski , Conor Dooley Cc: Geert Uytterhoeven , devicetree@vger.kernel.org, linux-leds@vger.kernel.org, linux-kernel@vger.kernel.org, =?UTF-8?Q?Andreas_F=C3=A4rber?= , Boris Gjenero , Christian Hewitt , Heiner Kallweit , Paolo Sabatino References: <20250629130002.49842-1-jefflessard3@gmail.com> <20250629130002.49842-8-jefflessard3@gmail.com> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit On 01/07/2025 05:22, Jean-François Lessard wrote: > Le 30 juin 2025 02 h 19 min 11 s HAE, Krzysztof Kozlowski a écrit : >> On 29/06/2025 14:59, Jean-François Lessard wrote: >>> Add documentation for Titanmec TM16XX and compatible LED display controllers. >>> >>> This patch is inspired by previous work from Andreas Färber and Heiner Kallweit. >> >> Please wrap commit message according to Linux coding style / submission >> process (neither too early nor over the limit): >> https://elixir.bootlin.com/linux/v6.4-rc1/source/Documentation/process/submitting-patches.rst#L597 >> >> Please do not use "This commit/patch/change", but imperative mood. See >> longer explanation here: >> https://elixir.bootlin.com/linux/v5.17.1/source/Documentation/process/submitting-patches.rst#L95 >> >>> >>> Co-developed-by: Andreas Färber >>> Co-developed-by: Heiner Kallweit >>> Signed-off-by: Jean-François Lessard >>> --- >>> .../bindings/auxdisplay/titanmec,tm16xx.yaml | 210 ++++++++++++++++++ >>> 1 file changed, 210 insertions(+) >>> create mode 100644 Documentation/devicetree/bindings/auxdisplay/titanmec,tm16xx.yaml >>> >>> diff --git a/Documentation/devicetree/bindings/auxdisplay/titanmec,tm16xx.yaml b/Documentation/devicetree/bindings/auxdisplay/titanmec,tm16xx.yaml >>> new file mode 100644 >>> index 0000000000..65c43e3ba4 >>> --- /dev/null >>> +++ b/Documentation/devicetree/bindings/auxdisplay/titanmec,tm16xx.yaml >>> @@ -0,0 +1,210 @@ >>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) >>> +%YAML 1.2 >>> +--- >>> +$id: http://devicetree.org/schemas/auxdisplay/titanmec,tm16xx.yaml# >> >> Why isn't this in leds directory? Everything below describes it as LED >> controller. >> > > TM16XX controllers are commonly used as auxiliary display drivers in consumer Android-based TV boxes for driving 7-segment and icon displays, rather than for generic LEDs. > > Previous attempts to place TM1628 drivers under LED subsystem were NAK’ed by LED maintainers, with Pavel Machek recommending drivers/auxdisplay instead (see https://lore.kernel.org/linux-devicetree/20200226130300.GB2800@duo.ucw.cz/). OK, it's fine. If you want to avoid the same question at v3, v4 and v5, please mention this in the patch changelog. ... >>> + compatible: >>> + enum: >>> + - titanmec,tm1618 >>> + - titanmec,tm1620 >>> + - titanmec,tm1628 >>> + - titanmec,tm1650 >>> + - fdhisi,fd620 >>> + - fdhisi,fd628 >>> + - fdhisi,fd650 >>> + - fdhisi,fd6551 >>> + - fdhisi,fd655 >>> + - icore,aip650 >>> + - icore,aip1618 >>> + - icore,aip1628 >>> + - princeton,pt6964 >>> + - winrise,hbs658 >> >> Several devices are compatible, so express it here and drop redundant >> entries in the driver. >> > > I understand the concern. I would appreciate your guidance since these are not always direct aliases. E.g.: > - tm1620 and fd620 varies on which bit is used for the 8th segment > - fd655 and fd650 have no titanmec counterpart > - hbs658 is similar to tm1628, yet distinct You did not get the point. I did not ask to make incompatible devices as compatible. I asked to make compatible devices compatible. Also wrap your emails to mailing list style. It's very difficult to read and respond to them. > > We could keep only known distinct implementations, that would yield to: > - titanmec,tm1618 > - titanmec,tm1620 > - titanmec,tm1628 > - titanmec,tm1650 > - fdhisi,fd620 > - fdhisi,fd650 > - fdhisi,fd6551 > - fdhisi,fd655 > - winrise,hbs658 I do not see compatibility expressed. You need front compatible and fallback. > > Which would be inconsistent for cases where vendors appear for another variant. > e.g. fdhisi,fd628 now being aliased by titanmec,tm1628 while other fdhisi variants are listed. I don't understand what that means. I don't understand what aliased means. There is no such term in DT bindings. > > Therefore I would suggest to keep fdhisi,fd628 even if implementation is the same as titanmec,tm1628. I don't understand the problem. > > icore and princeton could be dropped in favor of titanmec equivalents, at least for the variants I am aware of. Specific implementation for other variants can be let for future extension, if ever needed. No clue what you are saying here. > > How would you approach this? You have compatible devices, yes? If so, you drop irrelevant entries in device ID tables and use fallbacks in the bindings, just like roughly 80% of devices in the bindings. > >>> + >>> + reg: >>> + maxItems: 1 >>> + >>> + titanmec,digits: >>> + description: | >>> + Array of grid (row) indexes corresponding to specific wiring of digits in the display matrix. >> >> What is wiring of digits? This and other descriptions don't tell me much. >> > > Controllers use a matrix to drive LEDs. Terminology used in datasheets is: > - grids: matrix rows > - segments: matrix columns > > Board manufacturers wires display panels differently, including LEDs which are parts of 7-segments: > - “digits” refers to the ordered list of GRID indices wired to the physical 7-segment digit displays (arranged right to left) > - “segment-mapping” defines how each SEGMENT index within these grids maps to the standard 7-segment elements (a-g) > >> Wrap according to Linux coding style, so at 80. >> >>> + Defines which grid lines are connected to digit elements. >>> + $ref: /schemas/types.yaml#/definitions/uint8-array >>> + items: >>> + minimum: 0 >>> + maximum: 7 >>> + minItems: 1 >>> + maxItems: 8 >>> + >>> + titanmec,segment-mapping: >>> + description: | >> >> Do not need '|' unless you need to preserve formatting. >> >>> + Array of segment (column) indexes specifying the hardware layout mapping used for digit display. >>> + Each entry gives the segment index corresponding to a standard 7-segment element (a-g). >> >> Wrap according to Linux coding style, so at 80. >> >> This looks like duplicating the reg property. >> > > While related, this is not replicating the reg property of led child nodes. > > Each (grid,segment) combination might have a distinct role: > - part of a 7-segment: described using digits and segment-mapping properties > - individual led: described using led child nodes > >> >>> + $ref: /schemas/types.yaml#/definitions/uint8-array >>> + items: >>> + minimum: 0 >>> + maximum: 7 >>> + minItems: 7 >>> + maxItems: 7 >>> + >>> + titanmec,transposed: >>> + description: | >>> + Optional flag indicating if grids and segments are swapped compared to standard matrix orientation. >>> + This accommodates devices where segments are wired to rows and grids to columns. >>> + $ref: /schemas/types.yaml#/definitions/flag >>> + >>> + "#address-cells": >>> + const: 2 >>> + >>> + "#size-cells": >>> + const: 0 >>> + >>> +patternProperties: >>> + "^led@[0-7],[0-7]$": >> >> Why do you have two addresses? It's not used in your example. >> > > First is for the grid index, second of for the segment index. But it is not used. I really do not get why this is different than other matrix LED controllers. > >>> + $ref: /schemas/leds/common.yaml# >>> + properties: >>> + reg: >>> + description: Grid (row) and segment (column) index in the matrix of this individual LED icon >> >> Missing constraints. >> >>> + required: >>> + - reg >>> + > > Well noted. > >>> +required: >>> + - compatible >>> + - reg >>> + - titanmec,digits >>> + - titanmec,segment-mapping >>> + >>> +additionalProperties: true >> >> No, this cannot be true. Look at any other binding, look at example-schema. >> > > I got misled by "spi-3wire" which is not defined in spi-peripheral-props.yaml but only as a child node property of spi-controller.yaml. > > I wasn't sure how to implement this correctly. I have reviewed existing examples and will replace with: > > if: > properties: > compatible: > contains: > enum: > - titanmec,tm1618 > - titanmec,tm1620 > - titanmec,tm1628 > - fdhisi,fd620 > - fdhisi,fd628 > - winrise,hbs658 > then: > allOf: > - $ref: /schemas/spi/spi-peripheral-props.yaml# Why is this conditional? Are these devices with entirely different programming model? Then they usually should not be in the same binding, although depends on differences. > properties: > spi-3wire: true > required: > - spi-3wire Best regards, Krzysztof