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Mon, 31 Aug 2020 01:19:23 -0700 References: <20200513130842.24847-1-lars.povlsen@microchip.com> <20200513130842.24847-4-lars.povlsen@microchip.com> <20200528022502.GA3234572@bogus> <87wo4piyqz.fsf@soft-dev15.microsemi.net> <20200828163916.g6vbk3anfyijl7sx@earth.universe> From: Lars Povlsen To: Sebastian Reichel Subject: Re: [PATCH 3/5] dt-bindings: reset: ocelot: Add documentation for 'microchip, reset-switch-core' property In-Reply-To: <20200828163916.g6vbk3anfyijl7sx@earth.universe> Date: Mon, 31 Aug 2020 10:19:38 +0200 Message-ID: <871rjnxm5h.fsf@soft-dev15.microsemi.net> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200831_041945_427443_2F417073 X-CRM114-Status: GOOD ( 29.38 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Cc: Rob Herring , Alexandre Belloni , linux-pm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Microchip Linux Driver Support , SoC Team , linux-arm-kernel@lists.infradead.org, Lars Povlsen Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Sebastian Reichel writes: > Hi, > > On Tue, Jun 02, 2020 at 11:49:08AM +0200, Lars Povlsen wrote: > > Rob Herring writes: > > > On Wed, May 13, 2020 at 03:08:40PM +0200, Lars Povlsen wrote: > > >> This documents the 'microchip,reset-switch-core' property in the > > >> ocelot-reset driver. > > >> > > >> Signed-off-by: Lars Povlsen > > >> --- > > >> .../devicetree/bindings/power/reset/ocelot-reset.txt | 6 ++++++ > > >> 1 file changed, 6 insertions(+) > > >> > > >> diff --git a/Documentation/devicetree/bindings/power/reset/ocelot-rese= > t.txt b/Documentation/devicetree/bindings/power/reset/ocelot-reset.txt > > >> index 4d530d8154848..20fff03753ad2 100644 > > >> --- a/Documentation/devicetree/bindings/power/reset/ocelot-reset.txt > > >> +++ b/Documentation/devicetree/bindings/power/reset/ocelot-reset.txt > > >> @@ -9,9 +9,15 @@ microchip Sparx5 armv8 SoC's. > > >> Required Properties: > > >> - compatible: "mscc,ocelot-chip-reset" or "microchip,sparx5-chip-res= > et" > > >> > > >> +Optional properties: > > >> +- microchip,reset-switch-core : Perform a switch core reset at the > > >> + time of driver load. This is may be used to initialize the switch > > >> + core to a known state (before other drivers are loaded). > > > > > > How do you know when other drivers are loaded? This could be a module > > > perhaps. Doesn't seem like something that belongs in DT. > > > > > > > The reset driver is loaded at postcore_initcall() time, which ensures it > > is loaded before other drivers using the switch core. I noticed other > > drivers do the same to do low-level system reset and initialization at > > early boot time. > > > > > Can this behavior be implied with "microchip,sparx5-chip-reset"? > > > > Since we need to cater for both modus operandi, I would need two driver > > compatible strings per platform, which scales worse than a single > > property. > > > > The "microchip,reset-switch-core" is a device configuration property > > which tells the system (driver) how the hw should be handled. Since you > > do not *always* want to reset the switch core (f.ex. when implementing > > systems with warm reboot), I think it makes perfect sense - but I may be > > biased off course :-) > > > > Thank you for (all) of your comments, by the way! > > > > ---Lars > > > Rob > > Is this series still needed? Did I miss a follow-up? Hi Sebastian! Yes, the series is still needed, but the conversation died after my last message. If the DT-controlled reset property is too controversial, I am willing to drop that part. (Rob just reviewed the bindings). MCHP reference designs have GPIO resets, so we *could* get by without, but new designs may this feature. > -- Sebastian ---Lars -- Lars Povlsen, Microchip _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel