From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tomi Valkeinen Subject: Re: [PATCH 2/2] OMAPDSS: Ensure OPP100 when DSS is operational Date: Wed, 18 Apr 2012 16:13:35 +0300 Message-ID: <1334754815.2027.34.camel@deskari> References: <1331205217-19927-1-git-send-email-tomi.valkeinen@ti.com> <1331205217-19927-2-git-send-email-tomi.valkeinen@ti.com> <1331646353.2856.354.camel@deskari> <87zkbkmjo1.fsf@ti.com> <1331707131.1618.7.camel@lappy> Mime-Version: 1.0 Content-Type: multipart/signed; micalg="pgp-sha1"; protocol="application/pgp-signature"; boundary="=-YG6PiGVEqUmYEwIq6U5A" Return-path: Received: from na3sys009aog130.obsmtp.com ([74.125.149.143]:44212 "EHLO na3sys009aog130.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751382Ab2DRNNl (ORCPT ); Wed, 18 Apr 2012 09:13:41 -0400 Received: by lagz14 with SMTP id z14so7421332lag.14 for ; Wed, 18 Apr 2012 06:13:38 -0700 (PDT) In-Reply-To: <1331707131.1618.7.camel@lappy> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Kevin Hilman Cc: linux-omap@vger.kernel.org, Paul Walmsley , archit@ti.com --=-YG6PiGVEqUmYEwIq6U5A Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Ping. Tomi On Wed, 2012-03-14 at 08:38 +0200, Tomi Valkeinen wrote: > On Tue, 2012-03-13 at 11:37 -0700, Kevin Hilman wrote: > > Hi Tomi, > >=20 > > Tomi Valkeinen writes: > >=20 > > > Hi Kevin, Paul, > > > > > > I know you're busy, but I'd appreciate a comment/ack on these two sma= ll > > > patches, so I could get them in to next merge window. Otherwise using > > > any other OPP than OPP100 will most likely break the DSS. > > > > > > This looks quite straightforward fix for me, but I'm not sure if ther= e > > > could be any side effects. > >=20 > > How does it affect OMAP3? OPP50/OPP100 names are specific to OMAP4. >=20 > They are? At least 3630 TRM speaks of them in the DSS chapter. >=20 > > Also, Can you help us understand the exact nature of the constraint? >=20 > The TRM lists maximum clock rates for the DSS clocks. You should be able > to find them by searching "OPP100" in the DSS chapter. In my TRMs there > are: >=20 > OMAP3630: Table 7-19. Display Subsystem Clocks > OMAP4430: Table 10-4. DSS Clock Frequencies >=20 > > It sounds to me like it acutally is a throughput constraint on CORE. I= f > > so, wouldn't it be clearer to set a throughput constraint that is > > calculated based on the pixel clock and resulting bitrate that would > > have the same effect? >=20 > I don't see that these limits would have anything to do with CORE. I'm > guessing that the DSS HW just can't function properly with high clocks > and low voltage. >=20 > Making a constraint for the throughput is another matter, which should > be also fixed at some point. So in the future I hope we'll have PM > constraints coming from two sources: 1) a calculation based on the > memory throughput needs 2) the minimum clock rates. >=20 > But both of those are non-trivial to code, so this patch aims to keep > DSS working until those are implemented. Also, in practice, it's quite > rare that the DSS clocks would all be below the limits in the tables. > That could only happen with a fixed, known configuration with rather > small displays. >=20 > Tomi >=20 >=20 --=-YG6PiGVEqUmYEwIq6U5A Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iQIcBAABAgAGBQJPjr3/AAoJEPo9qoy8lh71McQP/0jlAB0o6ji/fB7isdymkCx1 PJnyfEDme8hNz9izdLGBrFkGhwk/tmq8JmdN8+VFqXbQpV2j5GZq5vIqZC55jPip maqFJ/jBq+uKs+GoXZjtPr/UbBqyHuYFseCo5SxVUxskATJ0l5AQDl3zhcSQXyeM NqEZs99Xx4iNBmmIhtmR8nxQNuvpwRPC3xSMa+Rz18bEP/YANRJci3o9DkHFV+gg GfX7z/kqWYhEgsyD5oeRuY5GCAkthazH9cpHAvaGoJinVpr8ZknX7cOEWGfNKohi Vo5mRk0sGsukvuLhIBJRvvWWEUrgHZayt2VUxmjWdZe5eP9jJSGKm7mQRIIUcrZX YuWFGRTCKFnazf3nv3hFMIENTJqsGB7/EjhiRwa9cu6zEiEgvZbkWkI9HVCwa0Iq NU3yX8zA786pOgzLZUBYFNT2aGryUpa25EfgLvX+H8Ci+oHUczmQr3S7Fgo8nY5N XzGY/j3Qa6mg8HrocEZ8dAChXa7rmZhkXSnzJeGoaiTvkB66Xe5XQFj9mVo2+U30 GQj0o0Fl3fhbbVFbXRa0r37cA14x8JWTfXxyMDui/oIT60TX2zNE93eRipIoIb3V Pvw2l/q4nkzkkF09Y9Ey96pgsZUkv6oDumBnM96eLlhv06QdcW1EbVmi705jZSzz DoG0tumaq+S+IE0Q6QCW =SQpI -----END PGP SIGNATURE----- --=-YG6PiGVEqUmYEwIq6U5A--