From mboxrd@z Thu Jan 1 00:00:00 1970 From: maxime.ripard@free-electrons.com (Maxime Ripard) Date: Mon, 1 Feb 2016 07:37:31 +0100 Subject: [linux-sunxi] Problem with Allwinner H3 clocks In-Reply-To: <56AB05EF.2090604@redhat.com> References: <20160127103714.58312b152adb4148bae2f93b@free.fr> <56A8D5E5.30701@gmail.com> <20160127175512.87caf31b5e21a1fec91507f2@free.fr> <56A9098A.5010107@redhat.com> <20160127200217.14dce96ade71cf81bc82e6f6@free.fr> <56A9CE3D.4020906@redhat.com> <56AA14AA.4070502@gmail.com> <20160128175918.78a916a8cd7bf4c0b2f2814f@free.fr> <20160128192931.GB32462@lukather> <56AB05EF.2090604@redhat.com> Message-ID: <20160201063731.GG32462@lukather> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi, On Fri, Jan 29, 2016 at 07:25:51AM +0100, Hans de Goede wrote: > Hi, > > On 01/28/2016 08:29 PM, Maxime Ripard wrote: > >On Thu, Jan 28, 2016 at 05:59:18PM +0100, Jean-Francois Moine wrote: > > > > >>The A23/A33/H3 (and surely some other SoCs) documentations about > >>the peripheral/periph/periph0/periph1 PLLs say: > >> > >> Note: The PLL Output should be fixed to 600MHz, it is not > >> recommended to vary this value arbitrarily. > > > >I don't know if it's worth it at this point. The pll6 seems to work > >fine at other rates. Have you experienced any breakage when running at > >another frequency? > > Hmm, are we actually changing the freq of pll6 on any SoCs? I know we've > the code to it, but given that it is shared between many pheripherals, > I assume we end up never changing it. We don't, but it works. Back when I was debugging the A31 DMA controller, I tried to do just that and nothing broke (at least as long as you don't switch halfway through during the boot, but at the time the clock is registered). > I assume / hope that the clock framework protects against reclocking > a clock with multiple users ... There is, but it's opt-in, and we're not using it yet for anything but the hstimers (and in that case, we don't prevent the reclocking, we just take it into account). Maxime -- Maxime Ripard, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 819 bytes Desc: Digital signature URL: