From: Sakari Ailus <sakari.ailus@linux.intel.com>
To: Benoit Parrot <bparrot@ti.com>
Cc: Jacopo Mondi <jacopo@jmondi.org>,
Hans Verkuil <hverkuil@xs4all.nl>,
linux-media@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org, hugues.fruchet@st.com
Subject: Re: [Patch 1/3] media: ov5640: add PIXEL_RATE control
Date: Wed, 2 Oct 2019 15:35:13 +0300 [thread overview]
Message-ID: <20191002123513.GI972@paasikivi.fi.intel.com> (raw)
In-Reply-To: <20191002121438.g3re6v54q4hit2wv@ti.com>
Hi Benoit,
On Wed, Oct 02, 2019 at 07:14:38AM -0500, Benoit Parrot wrote:
> Hi Jacopo,
>
> Maybe, I miss spoke when I mentioned a helper I did not intent a framework
> level generic function. Just a function to help in this case :)
>
> That being said, I re-read the thread you mentioned. And as Hughes pointed
> out dynamically generating a "working" link frequency value which can be
> used by a CSI2 receiver to properly configure its PHY is not trivial.
>
> When I created this patch, I also had another to add V4L2_CID_LINK_FREQ
> support. I am testing this against the TI CAL CSI2 receiver, which already
> uses the V4L2_CID_PIXEL_RATE value for that purpose, so I also had a patch
> to add support for V4L2_CID_LINK_FREQ to that driver as well.
>
> Unfortunately, similar to Hughes' findings I was not able to make it "work"
> with all supported resolution/framerate.
>
> Unlike my V4L2_CID_PIXEL_RATE solution which now works in all mode with the
> same receiver.
>
> So long story short I dropped the V4L2_CID_LINK_FREQ patch and focused on
> V4L2_CID_PIXEL_RATE instead.
It shouldn't make a difference which one you use; if you know the bus type
(and if it's CSI-2 with D-PHY, number of lanes and how many bits per pixel
the media bus format has), you can convert fairly trivially between the
two.
--
Sakari Ailus
sakari.ailus@linux.intel.com
next prev parent reply other threads:[~2019-10-02 12:35 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-25 15:22 [Patch 0/3] media: ov5640: updates Benoit Parrot
2019-09-25 15:22 ` [Patch 1/3] media: ov5640: add PIXEL_RATE control Benoit Parrot
2019-10-01 7:57 ` Sakari Ailus
2019-10-01 16:23 ` Benoit Parrot
2019-10-02 7:59 ` Jacopo Mondi
2019-10-02 12:14 ` Benoit Parrot
2019-10-02 12:35 ` Sakari Ailus [this message]
2019-10-02 12:40 ` Benoit Parrot
2019-10-02 14:32 ` Jacopo Mondi
2019-10-02 15:06 ` Benoit Parrot
2019-10-03 6:55 ` Jacopo Mondi
2019-09-25 15:23 ` [Patch 2/3] media: ov5640: Fix 1920x1080 mode to remove extra enable/disable Benoit Parrot
2019-09-25 15:23 ` [Patch 3/3] media: ov5640: Make 2592x1944 mode only available at 15 fps Benoit Parrot
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