From: Hugues FRUCHET <hugues.fruchet@st.com>
To: Sakari Ailus <sakari.ailus@linux.intel.com>
Cc: "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
Alexandre TORGUE <alexandre.torgue@st.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Philippe CORNU <philippe.cornu@st.com>,
Hans Verkuil <hverkuil@xs4all.nl>,
Alain VOLMAT <alain.volmat@st.com>,
Rob Herring <robh+dt@kernel.org>,
Yannick FERTRE <yannick.fertre@st.com>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
"linux-stm32@st-md-mailman.stormreply.com"
<linux-stm32@st-md-mailman.stormreply.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-media@vger.kernel.org" <linux-media@vger.kernel.org>
Subject: Re: [PATCH v4 2/2] media: dt-bindings: media: st,stm32-dcmi: Add support of BT656
Date: Wed, 21 Oct 2020 14:24:08 +0000 [thread overview]
Message-ID: <657634eb-690a-53a6-2ac1-de3c06a1cec4@st.com> (raw)
In-Reply-To: <20201021130033.GI2703@paasikivi.fi.intel.com>
Hi Sakari,
On 10/21/20 3:00 PM, Sakari Ailus wrote:
> Hi Hugues,
>
> On Tue, Oct 20, 2020 at 12:14:49PM +0200, Hugues Fruchet wrote:
>> Add support of BT656 parallel bus mode in DCMI.
>> This mode is enabled when hsync-active & vsync-active
>> fields are not specified.
>>
>> Signed-off-by: Hugues Fruchet <hugues.fruchet@st.com>
>> ---
>> .../devicetree/bindings/media/st,stm32-dcmi.yaml | 30 ++++++++++++++++++++++
>> 1 file changed, 30 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/media/st,stm32-dcmi.yaml b/Documentation/devicetree/bindings/media/st,stm32-dcmi.yaml
>> index 3fe778c..1ee521a 100644
>> --- a/Documentation/devicetree/bindings/media/st,stm32-dcmi.yaml
>> +++ b/Documentation/devicetree/bindings/media/st,stm32-dcmi.yaml
>> @@ -44,6 +44,36 @@ properties:
>> bindings defined in
>> Documentation/devicetree/bindings/media/video-interfaces.txt.
>>
>> + properties:
>> + endpoint:
>> + type: object
>> +
>> + properties:
>> + bus-width: true
>> +
>> + hsync-active:
>> + description:
>> + If both HSYNC and VSYNC polarities are not specified, BT656
>> + embedded synchronization is selected.
>> + default: 0
>> +
>> + vsync-active:
>> + description:
>> + If both HSYNC and VSYNC polarities are not specified, BT656
>> + embedded synchronization is selected.
>> + default: 0
>
> Should I understand this as if the polarities were not specified, BT.656
> will be used?
Yes, this is what is documented in video-interfaces.txt:
"
Note, that if HSYNC and VSYNC polarities are not specified, embedded
synchronization may be required, where supported.
"
and
"
/* If hsync-active/vsync-active are missing,
embedded BT.656 sync is used */
hsync-active = <0>; /* Active low */
vsync-active = <0>; /* Active low */
"
and I found also this in
Documentation/devicetree/bindings/media/renesas,vin.yaml
"
hsync-active:
description:
If both HSYNC and VSYNC polarities are not specified,
embedded
synchronization is selected.
default: 1
vsync-active:
description:
If both HSYNC and VSYNC polarities are not specified,
embedded
synchronization is selected.
default: 1
"
In the other hand I've found few occurences of "bus-type"
(marvell,mmp2-ccic.yaml), it is why I asked you if "bus-type" is the new
way to go versus previous way to signal BT656 (without hsync/vsync) ?
As explained previously, I prefer this last way for backward compatibility.
The bindings previously documented BT.601 (parallel) only, so
> it was somewhat ambigious to begin with. Is there a risk of interpreting
> old BT.601 bindings as BT.656?
I don't think so.
With bus-type property, I believe you could
> avoid at least that risk.
yes but as explained, I'll prefer not to amend current boards device
tree files.
>
> Also not specifying at least one of the default values leads to BT.656
> without bus-type. That could be addressed by removing the defaults.
>
I'm new to yaml, I've taken that from renesas,vin.yaml. Should I just
drop the "default: 1" lines ?
>> +
>> + pclk-sample: true
>> +
>> + remote-endpoint: true
>> +
>> + required:
>> + - remote-endpoint
>> +
>> + additionalProperties: false
>> +
>> + additionalProperties: false
>> +
>> required:
>> - compatible
>> - reg
>
BR,
Hugues.
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next prev parent reply other threads:[~2020-10-21 14:26 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-20 10:14 [PATCH v4 0/2] DCMI BT656 parallel bus mode support Hugues Fruchet
2020-10-20 10:14 ` [PATCH v4 1/2] media: stm32-dcmi: add support of BT656 bus Hugues Fruchet
2020-10-20 10:14 ` [PATCH v4 2/2] media: dt-bindings: media: st, stm32-dcmi: Add support of BT656 Hugues Fruchet
2020-10-21 13:00 ` [PATCH v4 2/2] media: dt-bindings: media: st,stm32-dcmi: " Sakari Ailus
2020-10-21 14:24 ` Hugues FRUCHET [this message]
2020-10-21 21:40 ` Sakari Ailus
2020-10-22 14:56 ` Hugues FRUCHET
2020-10-26 14:17 ` Rob Herring
2020-10-30 17:42 ` Sakari Ailus
2020-10-30 18:00 ` Jacopo Mondi
2020-10-30 20:09 ` Rob Herring
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