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charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240905_095225_107411_CA68EBA5 X-CRM114-Status: GOOD ( 30.13 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Andrew Lunn , Catalin Marinas , Michael Turquette , Claudiu Beznea , Eric Dumazet , Dragan Cvetic , Will Deacon , linux-clk@vger.kernel.org, linux-arch@vger.kernel.org, Rob Herring , Florian Fainelli , Lee Jones , Saravana Kannan , Broadcom internal kernel review list , linux-pci@vger.kernel.org, Jakub Kicinski , Paolo Abeni , Linus Walleij , devicetree@vger.kernel.org, Conor Dooley , Arnd Bergmann , linux-gpio@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, Bjorn Helgaas , linux-arm-kernel@lists.infradead.org, Derek Kiernan , Stephen Boyd , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, Stefan Wahren , netdev@vger.kernel.org, Krzysztof Kozlowski , "David S. Miller" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 05/09/2024 18:33, Andrea della Porta wrote: > Hi Krzysztof, > > On 20:27 Tue 03 Sep , Krzysztof Kozlowski wrote: >> On 03/09/2024 17:15, Andrea della Porta wrote: >>>>>>> + >>>>>>> + rp1_clocks: clocks@c040018000 { >>>>>> >>>>>> Why do you mix MMIO with non-MMIO nodes? This really does not look >>>>>> correct. >>>>>> >>>>> >>>>> Right. This is already under discussion here: >>>>> https://lore.kernel.org/all/ZtBzis5CzQMm8loh@apocalypse/ >>>>> >>>>> IIUC you proposed to instantiate the non-MMIO nodes (the three clocks) by >>>>> using CLK_OF_DECLARE. >>>> >>>> Depends. Where are these clocks? Naming suggests they might not be even >>>> part of this device. But if these are part of the device, then why this >>>> is not a clock controller (if they are controllable) or even removed >>>> (because we do not represent internal clock tree in DTS). >>> >>> xosc is a crystal connected to the oscillator input of the RP1, so I would >>> consider it an external fixed-clock. If we were in the entire dts, I would have >>> put it in root under /clocks node, but here we're in the dtbo so I'm not sure >>> where else should I put it. >> >> But physically, on which PCB, where is this clock located? > > xosc is a crystal, feeding the reference clock oscillator input pins of the RP1, > please see page 12 of the following document: > https://datasheets.raspberrypi.com/rp1/rp1-peripherals.pdf That's not the answer. Where is it physically located? > On Rpi5, the PCB is the very same as the one on which the BCM2712 (SoC) and RP1 > are soldered. Would you consider it external (since the crystal is outside the RP1) > or internal (since the oscillator feeded by the crystal is inside the RP1)? So it is on RPi 5 board? Just like every other SoC and every other vendor? Then just like every other SoC and every other vendor it is in board DTS file. > >> >>> >>> Regarding pclk and hclk, I'm still trying to understand where they come from. >>> If they are external clocks (since they are fixed-clock too), they should be >>> in the same node as xosc. CLK_OF_DECLARE does not seem to fit here because >> >> There is no such node as "/clocks" so do not focus on that. That's just >> placeholder but useless and it is inconsistent with other cases (e.g. >> regulators). > > Fine, I beleve that the root node would be okay then, or some other carefully named > node in root, if the clock is not internal to any chip. > >> >> If this is external oscillator then it is not part of RP1 and you cannot >> put it inside just to satisfy your drivers. > > Ack. > >> >>> there's no special management of these clocks, so no new clock definition is >>> needed. >> >>> If they are internal tree, I cannot simply get rid of them because rp1_eth node >>> references these two clocks (see clocks property), so they must be decalred >>> somewhere. Any hint about this?. >>> >> >> Describe the hardware. Show the diagram or schematics where is which device. > > Unfortunately I don't have the documentation (schematics or other info) about > how these two clocks (pclk and hclk) are arranged, but I'm trying to get > some insight about that from various sources. While we're waiting for some > (hopefully) more certain info, I'd like to speculate a bit. I would say that > they both probably be either external (just like xosc), or generated internally > to the RP1: > > If externals, I would place them in the same position as xosc, so root node > or some other node under root (eg.: /rp1-clocks) Just like /clocks, /rp1-clocks is not better. Neither /rp1-foo-clocks. I think there is some sort of big misunderstanding here. Is this RP1 co-processor on the RP board, connected over PCI to Broadcom SoC? > > If internals, I would leave them just where they are, i.e. inside the rp1 node > > Does it make sense? No, because you do not have xosc there, according to my knowledge. Best regards, Krzysztof