From: Thomas Zimmermann <tzimmermann@suse.de>
To: Geert Uytterhoeven <geert@linux-m68k.org>,
Maxime Ripard <maxime@cerno.tech>
Cc: "Karol Herbst" <kherbst@redhat.com>,
"David Airlie" <airlied@linux.ie>,
nouveau@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
"Phil Elwell" <phil@raspberrypi.com>,
"Emma Anholt" <emma@anholt.net>,
"Samuel Holland" <samuel@sholland.org>,
"Jernej Skrabec" <jernej.skrabec@gmail.com>,
"Chen-Yu Tsai" <wens@csie.org>, "Ben Skeggs" <bskeggs@redhat.com>,
linux-sunxi@lists.linux.dev, intel-gfx@lists.freedesktop.org,
"Hans de Goede" <hdegoede@redhat.com>,
"Rodrigo Vivi" <rodrigo.vivi@intel.com>,
linux-arm-kernel@lists.infradead.org,
"Tvrtko Ursulin" <tvrtko.ursulin@linux.intel.com>,
"Dom Cobley" <dom@raspberrypi.com>,
"Dave Stevenson" <dave.stevenson@raspberrypi.com>,
linux-kernel@vger.kernel.org,
"Mateusz Kwiatkowski" <kfyatek+publicgit@gmail.com>,
"Noralf Trønnes" <noralf@tronnes.org>
Subject: Re: [PATCH v2 10/33] drm/modes: Add a function to generate analog display modes
Date: Mon, 26 Sep 2022 13:17:52 +0200 [thread overview]
Message-ID: <c714b53d-8e18-9105-9e27-8b783f246082@suse.de> (raw)
In-Reply-To: <CAMuHMdXonxXiw4x2PvnQ=xedOQO1y=K0O8g1+ixeSvXmzcOOVw@mail.gmail.com>
[-- Attachment #1.1: Type: text/plain, Size: 1867 bytes --]
Hi
Am 26.09.22 um 12:34 schrieb Geert Uytterhoeven:
> Hi Maxime,
>
> On Mon, Sep 26, 2022 at 12:17 PM Maxime Ripard <maxime@cerno.tech> wrote:
>> On Fri, Sep 23, 2022 at 11:05:48AM +0200, Thomas Zimmermann wrote:
>>>> + /* 63.556us * 13.5MHz = 858 pixels */
>>>
>>> I kind of get what the comment wants to tell me, but the units don't add up.
>>
>> I'm not sure how it doesn't add up?
>>
>> We have a frequency in Hz (equivalent to s^-1) and a duration in s, so
>> the result ends up with no dimension, which is to be expected for a
>> number of periods?
>
> To make the units add up, it should be 13.5 Mpixel/s
> (which is what a pixel clock of 13.5 MHz really means ;-)
Sort of. It leaves the time value as a magic number, which obfuscates
what's happening.
The unit for htotal is pixels/scanline because if you multiply it with
the number of scanlines per frame (which is in vtotal), you get
pixels/frame. Multiplying with the frames per second results in the
pixel clock in pixels/second.
That's a bit much for this comment. Hence, I suggested to remove these
comments entirely and document the relation among the numbers in a more
prominent location. The documentation for drm_display_mode would be a
good place, I guess.
Best regards
Thomas
>
> Gr{oetje,eeting}s,
>
> Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
> -- Linus Torvalds
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 840 bytes --]
next prev parent reply other threads:[~2022-09-26 11:17 UTC|newest]
Thread overview: 75+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-22 14:25 [PATCH v2 00/33] drm: Analog TV Improvements Maxime Ripard
2022-09-22 14:25 ` [PATCH v2 01/33] drm/tests: Order Kunit tests in Makefile Maxime Ripard
2022-09-23 8:06 ` Thomas Zimmermann
2022-09-24 17:33 ` Noralf Trønnes
2022-09-22 14:25 ` [PATCH v2 02/33] drm/tests: Add Kunit Helpers Maxime Ripard
2022-09-24 17:56 ` Noralf Trønnes
2022-09-24 18:06 ` Noralf Trønnes
2022-09-26 9:36 ` Maxime Ripard
2022-09-26 12:15 ` Noralf Trønnes
2022-09-22 14:25 ` [PATCH v2 03/33] drm/atomic-helper: Rename drm_atomic_helper_connector_tv_reset to avoid ambiguity Maxime Ripard
2022-09-23 8:09 ` Thomas Zimmermann
2022-09-22 14:25 ` [PATCH v2 04/33] drm/connector: Rename subconnector state variable Maxime Ripard
2022-09-23 8:14 ` Thomas Zimmermann
2022-09-22 14:25 ` [PATCH v2 05/33] drm/atomic: Add TV subconnector property to get/set_property Maxime Ripard
2022-09-22 14:25 ` [PATCH v2 06/33] drm/connector: Rename legacy TV property Maxime Ripard
2022-09-22 20:44 ` Lyude Paul
2022-09-23 8:19 ` Thomas Zimmermann
2022-09-26 9:50 ` Maxime Ripard
2022-09-26 12:34 ` Thomas Zimmermann
2022-09-24 15:38 ` Noralf Trønnes
2022-09-22 14:25 ` [PATCH v2 07/33] drm/connector: Only register TV mode property if present Maxime Ripard
2022-09-22 14:25 ` [PATCH v2 08/33] drm/connector: Rename drm_mode_create_tv_properties Maxime Ripard
2022-09-22 20:45 ` Lyude Paul
2022-09-24 15:43 ` Noralf Trønnes
2022-09-22 14:25 ` [PATCH v2 09/33] drm/connector: Add TV standard property Maxime Ripard
2022-09-24 15:52 ` Noralf Trønnes
2022-09-26 10:01 ` Maxime Ripard
2022-09-26 12:59 ` Noralf Trønnes
2022-09-22 14:25 ` [PATCH v2 10/33] drm/modes: Add a function to generate analog display modes Maxime Ripard
2022-09-23 9:05 ` Thomas Zimmermann
2022-09-23 9:18 ` Jani Nikula
2022-09-23 10:16 ` Thomas Zimmermann
2022-09-26 10:18 ` Maxime Ripard
2022-09-26 10:55 ` Thomas Zimmermann
2022-09-26 10:17 ` Maxime Ripard
2022-09-26 10:34 ` Geert Uytterhoeven
2022-09-26 11:17 ` Thomas Zimmermann [this message]
2022-09-26 12:42 ` Maxime Ripard
2022-09-26 13:02 ` Thomas Zimmermann
2022-09-22 14:25 ` [PATCH v2 11/33] drm/modes: Only consider bpp and refresh before options Maxime Ripard
2022-09-22 14:25 ` [PATCH v2 12/33] drm/modes: parse_cmdline: Add support for named modes containing dashes Maxime Ripard
2022-09-22 14:25 ` [PATCH v2 13/33] drm/client: Add some tests for drm_connector_pick_cmdline_mode() Maxime Ripard
2022-09-23 9:15 ` Thomas Zimmermann
2022-09-23 9:26 ` Javier Martinez Canillas
2022-09-23 10:30 ` Thomas Zimmermann
2022-09-23 11:01 ` Javier Martinez Canillas
2022-09-23 11:14 ` Maxime Ripard
2022-09-23 11:59 ` Jani Nikula
2022-09-22 14:25 ` [PATCH v2 14/33] drm/modes: Move named modes parsing to a separate function Maxime Ripard
2022-09-22 14:25 ` [PATCH v2 15/33] drm/modes: Bail out of named mode parsing if empty Maxime Ripard
2022-09-22 14:25 ` [PATCH v2 16/33] drm/modes: Bail out of named mode parsing early if it's a number Maxime Ripard
2022-09-22 14:25 ` [PATCH v2 17/33] drm/modes: Bail out of named mode parsing early if it's an option Maxime Ripard
2022-09-22 14:25 ` [PATCH v2 18/33] drm/modes: Bail out of named mode parsing early if it's a status Maxime Ripard
2022-09-22 14:25 ` [PATCH v2 19/33] drm/modes: Switch to named mode descriptors Maxime Ripard
2022-09-22 14:25 ` [PATCH v2 20/33] drm/modes: Fill drm_cmdline mode from named modes Maxime Ripard
2022-09-22 14:25 ` [PATCH v2 21/33] drm/connector: Add pixel clock to cmdline mode Maxime Ripard
2022-09-22 14:25 ` [PATCH v2 22/33] drm/connector: Add a function to lookup a TV mode by its name Maxime Ripard
2022-09-22 14:25 ` [PATCH v2 23/33] drm/modes: Introduce the tv_mode property as a command-line option Maxime Ripard
2022-09-22 14:25 ` [PATCH v2 24/33] drm/modes: Properly generate a drm_display_mode from a named mode Maxime Ripard
2022-09-22 14:25 ` [PATCH v2 25/33] drm/modes: Introduce more named modes Maxime Ripard
2022-09-22 14:25 ` [PATCH v2 26/33] drm/atomic-helper: Add a TV properties reset helper Maxime Ripard
2022-09-22 14:25 ` [PATCH v2 27/33] drm/atomic-helper: Add an analog TV atomic_check implementation Maxime Ripard
2022-09-24 15:58 ` Noralf Trønnes
2022-09-22 14:25 ` [PATCH v2 28/33] drm/vc4: vec: Fix definition of PAL-M mode Maxime Ripard
2022-09-24 15:59 ` Noralf Trønnes
2022-09-22 14:25 ` [PATCH v2 29/33] drm/vc4: vec: Use TV Reset implementation Maxime Ripard
2022-09-22 14:25 ` [PATCH v2 30/33] drm/vc4: vec: Check for VEC output constraints Maxime Ripard
2022-09-24 16:00 ` Noralf Trønnes
2022-09-22 14:25 ` [PATCH v2 31/33] drm/vc4: vec: Convert to the new TV mode property Maxime Ripard
2022-09-24 17:09 ` Noralf Trønnes
2022-09-22 14:25 ` [PATCH v2 32/33] drm/vc4: vec: Add support for more analog TV standards Maxime Ripard
2022-09-24 17:12 ` Noralf Trønnes
2022-09-22 14:25 ` [PATCH v2 33/33] drm/sun4i: tv: Convert to the new TV mode property Maxime Ripard
2022-09-22 14:31 ` [PATCH v2 00/33] drm: Analog TV Improvements Maxime Ripard
2022-09-25 15:58 ` Noralf Trønnes
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=c714b53d-8e18-9105-9e27-8b783f246082@suse.de \
--to=tzimmermann@suse.de \
--cc=airlied@linux.ie \
--cc=bskeggs@redhat.com \
--cc=dave.stevenson@raspberrypi.com \
--cc=dom@raspberrypi.com \
--cc=dri-devel@lists.freedesktop.org \
--cc=emma@anholt.net \
--cc=geert@linux-m68k.org \
--cc=hdegoede@redhat.com \
--cc=intel-gfx@lists.freedesktop.org \
--cc=jernej.skrabec@gmail.com \
--cc=kfyatek+publicgit@gmail.com \
--cc=kherbst@redhat.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-sunxi@lists.linux.dev \
--cc=maxime@cerno.tech \
--cc=noralf@tronnes.org \
--cc=nouveau@lists.freedesktop.org \
--cc=phil@raspberrypi.com \
--cc=rodrigo.vivi@intel.com \
--cc=samuel@sholland.org \
--cc=tvrtko.ursulin@linux.intel.com \
--cc=wens@csie.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).