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[87.21.228.106]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-ada5d82d95bsm125977666b.57.2025.05.29.04.21.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 29 May 2025 04:21:05 -0700 (PDT) From: Andrea della Porta X-Google-Original-From: Andrea della Porta Date: Thu, 29 May 2025 13:22:40 +0200 To: Andrea della Porta Cc: Michael Turquette , Stephen Boyd , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Florian Fainelli , Broadcom internal kernel review list , Lorenzo Pieralisi , Krzysztof Wilczynski , Manivannan Sadhasivam , Bjorn Helgaas , Linus Walleij , Catalin Marinas , Will Deacon , Bartosz Golaszewski , Derek Kiernan , Dragan Cvetic , Arnd Bergmann , Greg Kroah-Hartman , Saravana Kannan , linux-clk@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-gpio@vger.kernel.org, Masahiro Yamada , Stefan Wahren , Herve Codina , Luca Ceresoli , Thomas Petazzoni , Andrew Lunn , Phil Elwell , Dave Stevenson , kernel-list@raspberrypi.com, Matthias Brugger Subject: Re: [PATCH v10 0/13] Add support for RaspberryPi RP1 PCI device using a DT overlay Message-ID: References: Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Please ignore this set since it has clobbered sequence number in subject. I'll resend it in a moment. Apologies for the inconvenience, Andrea On 12:49 Thu 29 May , Andrea della Porta wrote: > RP1 is an MFD chipset that acts as a south-bridge PCIe endpoint sporting > a pletora of subdevices (i.e. Ethernet, USB host controller, I2C, PWM, > etc.) whose registers are all reachable starting from an offset from the > BAR address. The main point here is that while the RP1 as an endpoint > itself is discoverable via usual PCI enumeraiton, the devices it contains > are not discoverable and must be declared e.g. via the devicetree. > > This patchset is an attempt to provide a minimum infrastructure to allow > the RP1 chipset to be discovered and perpherals it contains to be added > from a devictree overlay loaded during RP1 PCI endpoint enumeration. To > ensure compatibility with downstream, a devicetree already comprising the > RP1 node is also provided, so it's not strictly necessary to use the > dynamically loaded overlay if the devicetree is already fully defined at > the origin. > To achieve this modularity, the RP1 node DT definitions are arranged by > file inclusion as per following schema (the arrow points to the includer, > see also [9]): > > rp1-pci.dtso rp1.dtso > ^ ^ > | | > rp1-common.dtsi ----> rp1-nexus.dtsi ----> bcm2712-rpi-5-b.dts > ^ > | > bcm2712-rpi-5-b-ovl-rp1.dts > > Followup patches should add support for the several peripherals contained > in RP1. > > This work is based upon dowstream drivers code and the proposal from RH > et al. (see [1] and [2]). A similar approach is also pursued in [3]. > > The patches are ordered as follows: > > -PATCHES 1 to 3: add binding schemas for clock, gpio and RP1 peripherals. > They are needed to support the other peripherals, e.g. the ethernet mac > depends on a clock generated by RP1 and the phy is reset through the > on-board gpio controller. > > -PATCH 4 and 5: add clock and gpio device drivers. > > -PATCH 6: the devicetree node describing the RP1 chipset. > > -PATCH 7: this is the main patch to support RP1 chipset. It can work > either with a fully defined devicetree (i.e. one that already included > the rp1 node since boot time) or with a runtime loaded dtb overlay > which is linked as binary blob in the driver obj. This duality is > useful to comply with both downstream and upstream needs (see [9]). > The real dtso is in devicetree folder while the dtso in driver folder is > just a placeholder to include the real dtso. > In this way it is possible to check the dtso against dt-bindings. > The reason why drivers/misc has been selected as containing folder > for this driver can be seen in [6], [7] and [8]. > > -PATCH 8: add the external clock node (used by RP1) to the main dts. > > -PATCH 9: the fully fledged devictree containing also the rp1 node. > This devicetree is functionally similar to the one downstream is using. > > -PATCH 10 (OPTIONAL): this patch introduces a new scenario about how > the rp1 node is specified and loaded in DT. On top of the base DT > (without rp1 node), the fw loads this overlay and the end result is > the same devicetree as in patch 9, which is then passed to the next > stage (either the kernel or u-boot/bootloader). > While this patch is not strictly necessary and can therefore be dropped > (see [10]), it's not introducing much extra work and maybe can come > in handy while debugging. > > -PATCH 11: add the relevant kernel CONFIG_ options to defconfig. > > -PATCH 12: enable CONFIG_OF_OVERLAY in order for 'make defconfig' > to produce a configuration valid for the RP1 driver. Without this > patch, the user has to explicitly enable it since the misc driver > depends on OF_OVERLAY. > > -PATCH 13: collect all changes for MAINTAINERS file. > > This patchset is also a first attempt to be more agnostic wrt hardware > description standards such as OF devicetree and ACPI, where 'agnostic' > means "using DT in coexistence with ACPI", as been already promoted > by e.g. AL (see [4]). Although there's currently no evidence it will also > run out of the box on purely ACPI system, it is a first step towards > that direction. > > Many thanks, > Andrea della Porta > > Links: > - [1]: https://lpc.events/event/17/contributions/1421/attachments/1337/2680/LPC2023%20Non-discoverable%20devices%20in%20PCI.pdf > - [2]: https://lore.kernel.org/lkml/20230419231155.GA899497-robh@kernel.org/t/ > - [3]: https://lore.kernel.org/all/20240808154658.247873-1-herve.codina@bootlin.com/#t > - [4]: https://lore.kernel.org/all/73e05c77-6d53-4aae-95ac-415456ff0ae4@lunn.ch/ > - [5]: https://lore.kernel.org/all/20240626104544.14233-1-svarbanov@suse.de/ > - [6]: https://lore.kernel.org/all/20240612140208.GC1504919@google.com/ > - [7]: https://lore.kernel.org/all/83f7fa09-d0e6-4f36-a27d-cee08979be2a@app.fastmail.com/ > - [8]: https://lore.kernel.org/all/2024081356-mutable-everyday-6f9d@gregkh/ > - [9]: https://lore.kernel.org/all/Z87wTfChRC5Ruwc0@apocalypse/ > - [10]: https://lore.kernel.org/all/CAMEGJJ0f4YUgdWBhxvQ_dquZHztve9KO7pvQjoDWJ3=zd3cgcg@mail.gmail.com/#t > > CHANGES IN V10 > > > PATCH RELATED ------------------------------------------------- > > - Patch 10,11,12: Added: Reviewed-by: Reviewed-by: Florian Fainelli > > - Patches reworked to apply cleanly on broadcom/stblinux branches: > patch 1,2,3,6,8,9,10 -> devicetree/next > patch 11,12 -> defconfig/next > patch 4,5,7 -> drivers/next > patch 13 -> maintainers/next > > - Patch 13: new patch gathering all changes for MAINTAINERS > > > RP1 CLOCK DRIVER ------------------------------------ > > - Dropped some WARN_ONCE() lines that are basically useless > > - rp1_clock_set_parent() now returns EINVAL in case the parent check > is failing. As a result, rp1_clock_set_rate_and_parent() has also > been adapted to return rp1_clock_set_parent() retcode. > > - Return an ERR_PTR from rp1_register_clock() instead of just NULL > > - Dropped some unaesthetic blank lines > > - Disabled the builtin locking in regmap since we're already dealing > with concurrency in the code > > - rp1_clk_probe(): dropped dev_err_probe() as redundant due to commit > 12a0fd23e870 ("clk: Print an error when clk registration fails") >