From: "Noralf Trønnes" <noralf@tronnes.org>
To: Rob Herring <robh+dt@kernel.org>
Cc: maxime@cerno.tech, thierry.reding@gmail.com, sam@ravnborg.org,
dave.stevenson@raspberrypi.com, david@lechnology.com,
devicetree@vger.kernel.org, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH 1/3] dt-bindings: display: add bindings for MIPI DBI compatible SPI panels
Date: Mon, 24 Jan 2022 18:04:33 +0100 [thread overview]
Message-ID: <73d6d94b-bde1-4d8e-ed36-eeb2ad2534d4@tronnes.org> (raw)
In-Reply-To: <CAL_JsqLiw42zfaRPmszs2bmGbAcL5STSTVUtP0PyWnm=CaG8ug@mail.gmail.com>
Den 24.01.2022 17.42, skrev Rob Herring:
> On Mon, Jan 24, 2022 at 10:28 AM Noralf Trønnes <noralf@tronnes.org> wrote:
>>
>>
>>
>> Den 24.01.2022 17.08, skrev Rob Herring:
>>> On Sun, Jan 23, 2022 at 11:25 AM Noralf Trønnes <noralf@tronnes.org> wrote:
>>>>
>>>> Add binding for MIPI DBI compatible SPI panels.
>>>
>>> I'm sure we already have MIPI DBI panels. What's this for?
>>>
>>
>> It aims to use one driver to cover all MIPI DBI panels where the
>> controller setup is loaded from userspace in a firmware file.
>
> What's the solution when the user wants a splash screen in the
> bootloader and also wants multiple panels supported?
>
In that case the bootloader needs builtin support for the screen. The OS
driver can then detect that the controller is configured and just skip
the configure stage. I have yet to see someone implement suppport for
such a SPI panel in a bootloader though.
> Also, 1 driver doesn't dictate 1 compatible. A one to many
> relationship is fine and makes the decision entirely the OS's.
>
>> The cover
>> letter points to the discussion where Maxime proposed this:
>>
>> https://lore.kernel.org/dri-devel/20211129093946.xhp22mvdut3m67sc@houat/
>
> The proposal there is:
>
>> compatible = "panel-spi";
>> model = "panel-from-random-place-42";
>
> The same thing can be accomplished with this:
>
> compatible = "panel-from-random-place-42", "panel-spi";
>
> What's the advantage of hijacking 'model'?
>
That's what Maxime proposed, but having it in the compatible like this
is even better. I suppose it's ok for the driver to use the compatible
to load the firmware file?
Noralf.
WARNING: multiple messages have this Message-ID (diff)
From: "Noralf Trønnes" <noralf@tronnes.org>
To: Rob Herring <robh+dt@kernel.org>
Cc: devicetree@vger.kernel.org, david@lechnology.com,
dave.stevenson@raspberrypi.com, dri-devel@lists.freedesktop.org,
thierry.reding@gmail.com, maxime@cerno.tech, sam@ravnborg.org
Subject: Re: [PATCH 1/3] dt-bindings: display: add bindings for MIPI DBI compatible SPI panels
Date: Mon, 24 Jan 2022 18:04:33 +0100 [thread overview]
Message-ID: <73d6d94b-bde1-4d8e-ed36-eeb2ad2534d4@tronnes.org> (raw)
In-Reply-To: <CAL_JsqLiw42zfaRPmszs2bmGbAcL5STSTVUtP0PyWnm=CaG8ug@mail.gmail.com>
Den 24.01.2022 17.42, skrev Rob Herring:
> On Mon, Jan 24, 2022 at 10:28 AM Noralf Trønnes <noralf@tronnes.org> wrote:
>>
>>
>>
>> Den 24.01.2022 17.08, skrev Rob Herring:
>>> On Sun, Jan 23, 2022 at 11:25 AM Noralf Trønnes <noralf@tronnes.org> wrote:
>>>>
>>>> Add binding for MIPI DBI compatible SPI panels.
>>>
>>> I'm sure we already have MIPI DBI panels. What's this for?
>>>
>>
>> It aims to use one driver to cover all MIPI DBI panels where the
>> controller setup is loaded from userspace in a firmware file.
>
> What's the solution when the user wants a splash screen in the
> bootloader and also wants multiple panels supported?
>
In that case the bootloader needs builtin support for the screen. The OS
driver can then detect that the controller is configured and just skip
the configure stage. I have yet to see someone implement suppport for
such a SPI panel in a bootloader though.
> Also, 1 driver doesn't dictate 1 compatible. A one to many
> relationship is fine and makes the decision entirely the OS's.
>
>> The cover
>> letter points to the discussion where Maxime proposed this:
>>
>> https://lore.kernel.org/dri-devel/20211129093946.xhp22mvdut3m67sc@houat/
>
> The proposal there is:
>
>> compatible = "panel-spi";
>> model = "panel-from-random-place-42";
>
> The same thing can be accomplished with this:
>
> compatible = "panel-from-random-place-42", "panel-spi";
>
> What's the advantage of hijacking 'model'?
>
That's what Maxime proposed, but having it in the compatible like this
is even better. I suppose it's ok for the driver to use the compatible
to load the firmware file?
Noralf.
next prev parent reply other threads:[~2022-01-24 17:05 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-23 17:25 [PATCH 0/3] drm/panel: Add MIPI DBI compatible SPI driver Noralf Trønnes
2022-01-23 17:25 ` Noralf Trønnes
2022-01-23 17:25 ` [PATCH 1/3] dt-bindings: display: add bindings for MIPI DBI compatible SPI panels Noralf Trønnes
2022-01-23 17:25 ` Noralf Trønnes
2022-01-24 16:01 ` Rob Herring
2022-01-24 16:01 ` Rob Herring
2022-01-24 16:08 ` Rob Herring
2022-01-24 16:08 ` Rob Herring
2022-01-24 16:28 ` Noralf Trønnes
2022-01-24 16:28 ` Noralf Trønnes
2022-01-24 16:42 ` Rob Herring
2022-01-24 16:42 ` Rob Herring
2022-01-24 17:04 ` Noralf Trønnes [this message]
2022-01-24 17:04 ` Noralf Trønnes
2022-01-27 9:36 ` Maxime Ripard
2022-01-27 9:36 ` Maxime Ripard
2022-01-27 20:18 ` Rob Herring
2022-01-27 20:18 ` Rob Herring
2022-01-23 17:25 ` [PATCH 2/3] drm/mipi-dbi: Add driver_private member to struct mipi_dbi_dev Noralf Trønnes
2022-01-23 17:25 ` Noralf Trønnes
2022-01-23 17:25 ` [PATCH 3/3] drm/panel: Add MIPI DBI compatible SPI driver Noralf Trønnes
2022-01-23 17:25 ` Noralf Trønnes
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