linux-sunxi.lists.linux.dev archive mirror
 help / color / mirror / Atom feed
From: Maxime Ripard <maxime@cerno.tech>
To: Thomas Zimmermann <tzimmermann@suse.de>
Cc: "Jernej Skrabec" <jernej.skrabec@gmail.com>,
	"Rodrigo Vivi" <rodrigo.vivi@intel.com>,
	"Ben Skeggs" <bskeggs@redhat.com>,
	"David Airlie" <airlied@linux.ie>,
	"Joonas Lahtinen" <joonas.lahtinen@linux.intel.com>,
	"Emma Anholt" <emma@anholt.net>,
	"Karol Herbst" <kherbst@redhat.com>,
	"Samuel Holland" <samuel@sholland.org>,
	"Jani Nikula" <jani.nikula@linux.intel.com>,
	"Daniel Vetter" <daniel@ffwll.ch>,
	"Lyude Paul" <lyude@redhat.com>,
	"Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>,
	"Tvrtko Ursulin" <tvrtko.ursulin@linux.intel.com>,
	"Chen-Yu Tsai" <wens@csie.org>,
	"Hans de Goede" <hdegoede@redhat.com>,
	nouveau@lists.freedesktop.org,
	"Geert Uytterhoeven" <geert@linux-m68k.org>,
	"Dave Stevenson" <dave.stevenson@raspberrypi.com>,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	"Phil Elwell" <phil@raspberrypi.com>,
	intel-gfx@lists.freedesktop.org,
	"Noralf Trønnes" <noralf@tronnes.org>,
	"Dom Cobley" <dom@raspberrypi.com>,
	linux-sunxi@lists.linux.dev,
	"Mateusz Kwiatkowski" <kfyatek+publicgit@gmail.com>,
	dri-devel@lists.freedesktop.org
Subject: Re: [PATCH v2 10/33] drm/modes: Add a function to generate analog display modes
Date: Mon, 26 Sep 2022 12:17:16 +0200	[thread overview]
Message-ID: <20220926101716.urehomr2lzv5pqln@houat> (raw)
In-Reply-To: <72a8c3ce-ed03-0a77-fb92-eaa992eb86fe@suse.de>

[-- Attachment #1: Type: text/plain, Size: 985 bytes --]

Hi,

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?

If you're talking about the comment itself, then NTSC mandates that a
line is 63.556us long. If we're using a pixel clock at 13.5 MHz, it
means that the period (== pixel) is ~74ns, so we get 63556 / 74 = 858
pixels / line.

> I think you want to end up with 858 pixels/line =
> 
>   13,5 pixels/second / (60/2I frame/second * 525 lines/frame)
> 
> I: interlaced
> 
> Maybe just remove the short comments and document that in a more meaningful
> place.

I guess this is where it's meaningful, we really want to hit that
target. BT601 also mandates it.

Maxime

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 228 bytes --]

  parent reply	other threads:[~2022-09-26 10:17 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 [this message]
2022-09-26 10:34       ` Geert Uytterhoeven
2022-09-26 11:17         ` Thomas Zimmermann
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=20220926101716.urehomr2lzv5pqln@houat \
    --to=maxime@cerno.tech \
    --cc=airlied@linux.ie \
    --cc=bskeggs@redhat.com \
    --cc=daniel@ffwll.ch \
    --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=jani.nikula@linux.intel.com \
    --cc=jernej.skrabec@gmail.com \
    --cc=joonas.lahtinen@linux.intel.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=lyude@redhat.com \
    --cc=maarten.lankhorst@linux.intel.com \
    --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=tzimmermann@suse.de \
    --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).