Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Feedback-ID: i8771445c:Fastmail
Date:   Wed, 29 Mar 2023 21:58:02 +0200
From:   Maxime Ripard <maxime@cerno.tech>
To:     Roman Beranek <romanberanek@icloud.com>
Cc:     Frank Oltmanns <frank@oltmanns.dev>, Chen-Yu Tsai <wens@csie.org>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        Jernej Skrabec <jernej.skrabec@gmail.com>,
        Samuel Holland <samuel@sholland.org>,
        dri-devel@lists.freedesktop.org,
        linux-arm-kernel@lists.infradead.org, linux-sunxi@lists.linux.dev,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] drm/sun4i: uncouple DSI dotclock divider from
 TCON0_DCLK_REG
Message-ID: <20230329195802.veybo3367zifw77n@penduick>
References: <20230320161636.24411-1-romanberanek@icloud.com>
 <87wn356ni4.fsf@oltmanns.dev>
 <20230327202045.ceeqqwjug4ktxtsf@penduick>
 <CRHKFX934UA0.1MCKCD8SJSPIE@iMac.local>
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha512;
        protocol="application/pgp-signature"; boundary="jhubbfpnry7jtl6t"
Content-Disposition: inline
In-Reply-To: <CRHKFX934UA0.1MCKCD8SJSPIE@iMac.local>
Precedence: bulk


--jhubbfpnry7jtl6t
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

On Tue, Mar 28, 2023 at 01:48:33AM +0200, Roman Beranek wrote:
> On Mon Mar 27, 2023 at 10:20 PM CEST, Maxime Ripard wrote:
> >
> > On Sat, Mar 25, 2023 at 12:40:04PM +0100, Frank Oltmanns wrote:
> > > Claiming to set the divider to a different value (bpp / lanes) than w=
hat we=E2=80=99re actually using in
> > > the end (SUN6I_DSIO_TCON_DIV) is somehow bugging me. I feel like the =
proposal that I submitted is
> > > more direct: <https://lore.kernel.org/all/20230319160704.9858-2-frank=
@oltmanns.dev/>
> >
> > Yeah, this patch looks better to me too: it's simpler, more straightfor=
ward. If Roman can confirm it
> > works with his testing, I'll be happy to merge it.
> >
>=20
> So I've just found out that my understanding of what sun4i_dotclock is
> was wrong the whole time. I treated it as a virtual clock representing
> the true CRTC pixel clock and only coincidentally also matching what
> A64 Reference Manual labels as TCON0 data clock (a coincidence to which
> DSI is an exception).
>=20
> Now that I finally see dotclock as 'what could dclk be an abbreviation
> to', I to agree that it's not only straightforward but also correct to
> keep the divider at 4 and adjust the rate as is done it the patch Frank
> submitted.
>=20
> In order to preserve semantic correctness however, I propose to preface
> the change with a patch that renames sun4i_dotclock and tcon-pixel-clock
> such that dot/pixel is replaced with d/data. What do you think?

I don't think it's exposed to the userspace in any way so it makes sense to=
 me

Maxime

--jhubbfpnry7jtl6t
Content-Type: application/pgp-signature; name="signature.asc"

-----BEGIN PGP SIGNATURE-----

iHUEABYKAB0WIQRcEzekXsqa64kGDp7j7w1vZxhRxQUCZCSYSgAKCRDj7w1vZxhR
xQgyAP4iRhVGZNaSGJ5BGI2H6CXWA1Oi2JNtRr4PQZ4IkSWWIwD/Zqs+v+sDPinR
jz7XAk8q+wY/CSPp0d7d34Th7Zj6qgQ=
=KqnG
-----END PGP SIGNATURE-----

--jhubbfpnry7jtl6t--