From mboxrd@z Thu Jan 1 00:00:00 1970 From: Codrin Ciubotariu Subject: Re: [PATCH v4 1/7] dt-bindings: clk: at91: add an I2S mux clock Date: Thu, 7 Jun 2018 13:30:14 +0300 Message-ID: <18f6871e-794d-3ea2-487e-32399a8b89b4@microchip.com> References: <1527251668-31396-1-git-send-email-codrin.ciubotariu@microchip.com> <1527251668-31396-2-git-send-email-codrin.ciubotariu@microchip.com> <20180531005827.GA17203@rob-hp-laptop> <4f2e6e6a-df3a-b645-093c-b4467b3aa843@microchip.com> <152778070837.144038.4555982304713569160@swboyd.mtv.corp.google.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Rob Herring , Stephen Boyd , Alexandre Belloni , Mark Brown Cc: devicetree@vger.kernel.org, Linux-ALSA , "linux-kernel@vger.kernel.org" , Boris Brezillon , Cristian.Birsan@microchip.com, linux-clk , "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" List-Id: devicetree@vger.kernel.org On 31.05.2018 18:56, Rob Herring wrote: > On Thu, May 31, 2018 at 10:31 AM, Stephen Boyd wrote: >> Quoting Rob Herring (2018-05-31 07:20:57) >>> On Thu, May 31, 2018 at 5:25 AM, Codrin Ciubotariu >>> wrote: >>>> On 31.05.2018 03:58, Rob Herring wrote: >>>>> >>>>> On Fri, May 25, 2018 at 03:34:22PM +0300, Codrin Ciubotariu wrote: >>>>>> >>>>>> The I2S mux clock can be used to select the I2S input clock. The >>>>>> available parents are the peripheral and the generated clocks. >>>>>> >>>>>> Signed-off-by: Codrin Ciubotariu >>>>>> --- >>>>>> .../devicetree/bindings/clock/at91-clock.txt | 34 >>>>>> ++++++++++++++++++++++ >>>>>> 1 file changed, 34 insertions(+) >>>>>> >>>>>> diff --git a/Documentation/devicetree/bindings/clock/at91-clock.txt >>>>>> b/Documentation/devicetree/bindings/clock/at91-clock.txt >>>>>> index 51c259a..1c46b3c 100644 >>>>>> --- a/Documentation/devicetree/bindings/clock/at91-clock.txt >>>>>> +++ b/Documentation/devicetree/bindings/clock/at91-clock.txt >>>>>> @@ -90,6 +90,8 @@ Required properties: >>>>>> "atmel,sama5d2-clk-audio-pll-pmc" >>>>>> at91 audio pll output on AUDIOPLLCLK that feeds the PMC >>>>>> and can be used by peripheral clock or generic clock >>>>>> + "atmel,sama5d2-clk-i2s-mux": >>>>>> + at91 I2S clock source selection >>>>> >>>>> >>>>> Is this boolean or takes some values. If latter, what are valid values? >>>> >>>> >>>> This is the compatible string of the clock driver. >>> >>> Ah, now I remember. AT91 uses fine grained clock nodes in DT. Is there >>> still a plan to fix this? >> >> I'm also interested in a plan. >> >>>>> >>>>>> + compatible = "atmel,sama5d2-clk-i2s-mux"; >>>>>> + #address-cells = <1>; >>>>>> + #size-cells = <0>; >>>>> >>>>> >>>>> How do you address this block? My guess is you don't because it is just >>>>> part of some other block and you are just creating this node to >>>>> instantiate a driver. Just make the node for the actual h/w block a >>>>> clock provider and define the clock ids (0 and 1). >>>> >>>> >>>> This block is not addressed, but its children are. The register we access in >>>> this driver is not part of other block. It's a SFR register, accessed >>>> through syscon and it has nothing to do with the I2S IP (see SAMA5D2 DS, >>>> page 1256, fig. 44-1: I2SC Block Diagram) that is the consumer of this >>>> clock. Adding a clock-id property in the I2S node would be just like v3 of >>>> this series, with the difference that we use clock-id instead of alias id to >>>> set the clock parent, which is not how you suggested back then. >>> >>> I wasn't suggesting a clock-id property, but a clock specifier (i.e. >>> make #clock-cells 1). >>> >>> But AT91 clocks are all a mess, so I don't know what to tell you. >>> >> >> If #clock-cells of 1 works then we should go with that. It's still weird >> that we need random nodes to add more clks, but I guess that's how it's >> going to be for each at91 clk driver until it changes to be one big >> provider node. > > Seems to me that clock additions could use a new binding and we start > with a new driver that handles these few clocks initially. But I > haven't looked whether both can coexist. Mark already applied to broonie/sound.git the I2S bindings that have a phandle to this clock. If I am to change #clock-cells to 1, I will have to change the bindings to include the clock-id. Which approach should I take now? Thanks and best regards, Codrin