From: Jose Abreu <Jose.Abreu@synopsys.com>
To: Hans Verkuil <hansverk@cisco.com>,
Jose Abreu <Jose.Abreu@synopsys.com>,
Hans Verkuil <hverkuil@xs4all.nl>, <linux-media@vger.kernel.org>,
<linux-kernel@vger.kernel.org>
Cc: Carlos Palminha <CARLOS.PALMINHA@synopsys.com>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Hans Verkuil <hans.verkuil@cisco.com>,
"Sylwester Nawrocki" <snawrocki@kernel.org>
Subject: Re: [PATCH v5 2/4] [media] platform: Add Synopsys Designware HDMI RX Controller Driver
Date: Tue, 4 Jul 2017 13:33:50 +0100 [thread overview]
Message-ID: <93a7aa80-52c5-86c4-c264-37849b467dd3@synopsys.com> (raw)
In-Reply-To: <e79b8482-342d-3300-21b7-073bbad6df36@cisco.com>
On 04-07-2017 10:39, Hans Verkuil wrote:
>
>>>>>> +static const struct v4l2_subdev_video_ops
>>>>>> dw_hdmi_sd_video_ops = {
>>>>>> + .s_routing = dw_hdmi_s_routing,
>>>>>> + .g_input_status = dw_hdmi_g_input_status,
>>>>>> + .g_parm = dw_hdmi_g_parm,
>>>>>> + .g_dv_timings = dw_hdmi_g_dv_timings,
>>>>>> + .query_dv_timings = dw_hdmi_query_dv_timings,
>>>>> No s_dv_timings???
>>>> Hmm, yeah, I didn't implement it because the callchain and the
>>>> player I use just use {get/set}_fmt. s_dv_timings can just
>>>> populate the fields and replace them with the detected dv_timings
>>>> ? Just like set_fmt does? Because the controller has no scaler.
>>> No, s_dv_timings is the function that actually sets
>>> dw_dev->timings.
>>> After you check that it is valid of course (call
>>> v4l2_valid_dv_timings).
>>>
>>> set_fmt calls get_fmt which returns the information from
>>> dw_dev->timings.
>>>
>>> But it is s_dv_timings that has to set dw_dev->timings.
>>>
>>> With the current code you can only capture 640x480 (the default
>>> timings).
>>> Have you ever tested this with any other timings? I don't quite
>>> understand
>>> how you test.
>> I use mpv to test with a wrapper driver that just calls the
>> subdev ops and sets up a video dma.
>>
>> Ah, I see now. I failed to port the correct callbacks and in the
>> upstream version I'm using I only tested with 640x480 ...
>>
>> But apart from that this is a capture device without scaling so I
>> can not set timings, I can only return them so that applications
>> know which format I'm receiving, right? So my s_dv_timings will
>> return the same as query_dv_timings ...
> Well, to be precise: s_dv_timings just accepts what the application
> gives it (as long as it is within the dv_timings capabilities). But
> those timings come in practice from a query_dv_timings call from the
> application.
>
> The core rule is that receivers cannot randomly change timings since
> timings are related to buffer sizes. You do not want the application
> to allocate buffers for 640x480 and when the source changes to 1920x1080
> have those buffers suddenly overflow.
>
> Instead the app queries the timings, allocates the buffers, start
> streaming and when the timings change it will get an event so it can
> stop streaming, reallocate buffers, and start the process again.
>
> In other words, the application is in control here.
>
... But this is not true for mpv/mplayer. They first try to set a
default format (by using s_fmt) and then query the format again
(by using g_fmt) ... So dv_timings are never used. Are these apps
broken? Im only using them because of performance, do you
recommend others?
Best regards,
Jose Miguel Abreu
next prev parent reply other threads:[~2017-07-04 12:34 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-29 10:46 [PATCH v5 0/4] Synopsys Designware HDMI Video Capture Controller + PHY Jose Abreu
2017-06-29 10:46 ` [PATCH v5 1/4] [media] platform: Add Synopsys Designware HDMI RX PHY e405 Driver Jose Abreu
2017-06-29 10:46 ` [PATCH v5 2/4] [media] platform: Add Synopsys Designware HDMI RX Controller Driver Jose Abreu
2017-07-03 9:27 ` Hans Verkuil
2017-07-03 9:53 ` Jose Abreu
2017-07-03 10:33 ` Hans Verkuil
2017-07-04 9:28 ` Jose Abreu
2017-07-04 9:39 ` Hans Verkuil
2017-07-04 12:33 ` Jose Abreu [this message]
2017-07-04 13:02 ` Hans Verkuil
2017-07-04 13:50 ` Jose Abreu
2017-07-04 14:04 ` Hans Verkuil
2017-06-29 10:46 ` [PATCH v5 3/4] MAINTAINERS: Add entry for Synopsys Designware HDMI drivers Jose Abreu
2017-06-29 10:46 ` [PATCH v5 4/4] dt-bindings: media: Document Synopsys Designware HDMI RX Jose Abreu
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