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From: Neil Armstrong <narmstrong@baylibre.com>
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Phong LE <ple@baylibre.com>,
	airlied@linux.ie, daniel@ffwll.ch, robh+dt@kernel.org,
	mark.rutland@arm.com, a.hajda@samsung.com, jonas@kwiboo.se,
	jernej.skrabec@siol.net, sam@ravnborg.org, mripard@kernel.org,
	heiko.stuebner@theobroma-systems.com, linus.walleij@linaro.org,
	stephan@gerhold.net, icenowy@aosc.io, broonie@kernel.org,
	mchehab+samsung@kernel.org, davem@davemloft.net,
	gregkh@linuxfoundation.org, Jonathan.Cameron@huawei.com,
	andriy.shevchenko@linux.intel.com,
	dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/4] dt-bindings: display: bridge: add it66121 bindings
Date: Fri, 13 Mar 2020 16:29:58 +0100	[thread overview]
Message-ID: <87a0d129-163b-18ae-eb09-cf7df4048dad@baylibre.com> (raw)
In-Reply-To: <20200313141713.GG4751@pendragon.ideasonboard.com>

On 13/03/2020 15:17, Laurent Pinchart wrote:
> Hi Neil,
> 
> On Fri, Mar 13, 2020 at 03:12:13PM +0100, Neil Armstrong wrote:
>> On 13/03/2020 14:40, Laurent Pinchart wrote:
>>> On Wed, Mar 11, 2020 at 01:51:33PM +0100, Phong LE wrote:
>>>> Add the ITE bridge HDMI it66121 bindings.
>>>>
>>>> Signed-off-by: Phong LE <ple@baylibre.com>
>>>> ---
>>>>  .../bindings/display/bridge/ite,it66121.yaml  | 98 +++++++++++++++++++
>>>>  1 file changed, 98 insertions(+)
>>>>  create mode 100644 Documentation/devicetree/bindings/display/bridge/ite,it66121.yaml
>>>>

[...]

>>>> +
>>>> +  pclk-dual-edge:
>>>> +    maxItems: 1
>>>> +    description: enable pclk dual edge mode.
>>>
>>> I'm having a bit of trouble understanding how this operates. Looking at
>>> the driver code the property is only taken into account to calculate the
>>> maximum allowed frequency. How is the IT66121 configured for single vs.
>>> dual pixel clock edge mode ?
>>
>> Dual edge mode is Dual-Data-Rate mode, the normal mode is MEDIA_BUS_FMT_RGB888_1X24 and dual edge is
>> MEDIA_BUS_FMT_RGB888_2X12_LE (or MEDIA_BUS_FMT_RGB888_2X12_BE, not sure) on a single clock period.
>>
>> This should be negociated at runtime, but the bus width should be specified somewhere to select
>> one of the modes.
> 
> How about replacing this property by bus-width to report the connected
> bus width ? It should then become an endpoint property.

It was my thought.

The mediatek dpi also uses this property, which is also very wrong in the same way.

Neil

[...]

  reply	other threads:[~2020-03-13 15:30 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-11 12:51 [PATCH v2 0/4] Add it66121 driver Phong LE
2020-03-11 12:51 ` [PATCH v2 1/4] dt-bindings: add ITE vendor Phong LE
2020-03-23 22:04   ` Rob Herring
2020-03-11 12:51 ` [PATCH v2 2/4] dt-bindings: display: bridge: add it66121 bindings Phong LE
2020-03-13 13:40   ` Laurent Pinchart
2020-03-13 14:12     ` Neil Armstrong
2020-03-13 14:17       ` Laurent Pinchart
2020-03-13 15:29         ` Neil Armstrong [this message]
2020-03-23 22:09   ` Rob Herring
2020-03-11 12:51 ` [PATCH v2 3/4] drm: bridge: add it66121 driver Phong LE
2020-03-11 13:55   ` Andy Shevchenko
2020-03-12  0:53     ` Laurent Pinchart
2020-03-12  8:40       ` Andy Shevchenko
2020-03-13 13:55   ` Laurent Pinchart
2020-06-11 15:22   ` Drew Fustini
2020-03-11 12:51 ` [PATCH v2 4/4] MAINTAINERS: add it66121 HDMI bridge driver entry Phong LE
2020-03-11 13:22   ` Andy Shevchenko

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