From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans de Goede Date: Mon, 15 Dec 2014 16:48:10 +0100 Subject: [U-Boot] [PATCH 2/2] sun7i: Add PSCI v0.2 support In-Reply-To: <548EFDF1.9010404@siemens.com> References: <3801faf2e649b0908a93f12d1bca30de26392bd0.1418643457.git.jan.kiszka@siemens.com> <548EC9A2.1040108@redhat.com> <548EFDF1.9010404@siemens.com> Message-ID: <548F02BA.6030000@redhat.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hi, On 15-12-14 16:27, Jan Kiszka wrote: > On 2014-12-15 12:44, Hans de Goede wrote: >> Hi, >> >> On 15-12-14 12:37, Jan Kiszka wrote: >>> This extends the PSCI support for the A20 to a dual v0.2 and v0.1 >>> interface. Recent OSes will prefer v0.2, olders will still find the >>> original interface, just at v0.2 service IDs. >>> >>> In addition to the existing services, v0.2 requires us to implement both >>> system off and reset. At least Linux will make use of them in favor of >>> its own implementations and, thus, fail if they do not work. >> >> Ugh, that may be a problem, as at least power off is highly SoC specific >> (different pmics, and newer pmics have a different bus) and somewhat board >> specific. > > Yes, that was my first thought as well. > >> >> I think we may avoid adding any board specific stuff for now, since we >> only want PSCI support on A20 and later and the only boards I know >> of which are not using the standard axp pmics are all A10 / A13 boards, >> but this might come back to bite us in the future. > > Good - so this is a conceptual ack for this patch? I guess so I'm still not enthusiastic, but given that there seems no other way (as you indicate below) and that for now I do not foresee any issues, as long as we do a different psci.S per SoC (one for each of sun6i sun7i and sun8i at least), we should be able to make this work. So yes I can live with this. Note it still does not make me happy though (not your fault). > >> >> Can't we just return -ENOTSUPPORTED or some such ? > > Unfortunately not. I don't know what was the intention of the designed > of this spec regarding mandatory SYSTEM_OFF and SYSTEM_RESET support. > Both functions are not supposed to return at all, and the kernel panics > when you return from SYSTEM_OFF. Not nice, but nothing we can do to fix the retroactively. Regards, Hans