linux-kernel - Re: [RESEND PATCH v2 2/6] ARM: dts: Specify clocks for UARTs on bcm11351

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Message-ID: <CAAYSxhoM2s_Yjy_FpUKjwgCCe=F+vSfPTyR0tKRUeHi1=-x3pA@mail.gmail.com>
Date:	Mon, 21 Oct 2013 11:56:43 -0700
From:	Tim Kryger <tim.kryger@...aro.org>
To:	Mark Rutland <mark.rutland@....com>
Cc:	Christian Daudt <bcm@...thebug.org>,
	"rob.herring@...xeda.com" <rob.herring@...xeda.com>,
	Pawel Moll <Pawel.Moll@....com>,
	Stephen Warren <swarren@...dotorg.org>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Chris Ball <cjb@...top.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
	"patches@...aro.org" <patches@...aro.org>
Subject: Re: [RESEND PATCH v2 2/6] ARM: dts: Specify clocks for UARTs on bcm11351

On Thu, Oct 17, 2013 at 6:56 AM, Mark Rutland <mark.rutland@....com> wrote:
> On Wed, Oct 16, 2013 at 10:47:06PM +0100, Tim Kryger wrote:
>> Rather than declaring the frequency of the external clock, specify the
>> label of the clock such that the driver may determine the frequency on
>> its own.
>
> Nit: we're not specifying the label of the clock. Clocks are represented
> py a phand+args pair, and the important part is that we're specifying
> the clock itself.
>
> How about something like:
>
> ---->8----
> Currently the rate of the external clock input to "snps,dw-apb-uart"
> devices is described by a clock-frequency property rather than by
> reference to the clock itself.
>
> This patch changes the "snps,dw-apb-uart" entries in bcm11351.dtsi to
> refer to the parent clock directly, following the common clock bindings.
> ---->8----

Would this be acceptable?

The frequency property in "snps,dw-apb-uart" entries are no longer
required if the rate of the external clock can be determined using the
clk api (see e302cd9 serial: 8250_dw: add support for clk api).

This patch replaces the frequency property in the UART nodes of
bcm11351.dtsi with references to the relevant clocks following the
common clock binding.

>
> Also, this should probably be moved after the driver change, so as to
> not be unbootable temporarily.

The driver change was part of v3.10 so there is no issue here.

>
> Thanks,
> Mark.
>
>>
>> Signed-off-by: Tim Kryger <tim.kryger@...aro.org>
>> Reviewed-by: Markus Mayer <markus.mayer@...aro.org>
>> Reviewed-by: Matt Porter <matt.porter@...aro.org>
>> ---
>>  arch/arm/boot/dts/bcm11351.dtsi | 8 ++++----
>>  1 file changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/arm/boot/dts/bcm11351.dtsi b/arch/arm/boot/dts/bcm11351.dtsi
>> index c6464fb..ce65367 100644
>> --- a/arch/arm/boot/dts/bcm11351.dtsi
>> +++ b/arch/arm/boot/dts/bcm11351.dtsi
>> @@ -43,7 +43,7 @@
>>               compatible = "brcm,bcm11351-dw-apb-uart", "snps,dw-apb-uart";
>>               status = "disabled";
>>               reg = <0x3e000000 0x1000>;
>> -             clock-frequency = <13000000>;
>> +             clocks = <&uartb_clk>;
>>               interrupts = <GIC_SPI 67 IRQ_TYPE_LEVEL_HIGH>;
>>               reg-shift = <2>;
>>               reg-io-width = <4>;
>> @@ -53,7 +53,7 @@
>>               compatible = "brcm,bcm11351-dw-apb-uart", "snps,dw-apb-uart";
>>               status = "disabled";
>>               reg = <0x3e001000 0x1000>;
>> -             clock-frequency = <13000000>;
>> +             clocks = <&uartb2_clk>;
>>               interrupts = <GIC_SPI 66 IRQ_TYPE_LEVEL_HIGH>;
>>               reg-shift = <2>;
>>               reg-io-width = <4>;
>> @@ -63,7 +63,7 @@
>>               compatible = "brcm,bcm11351-dw-apb-uart", "snps,dw-apb-uart";
>>               status = "disabled";
>>               reg = <0x3e002000 0x1000>;
>> -             clock-frequency = <13000000>;
>> +             clocks = <&uartb3_clk>;
>>               interrupts = <GIC_SPI 65 IRQ_TYPE_LEVEL_HIGH>;
>>               reg-shift = <2>;
>>               reg-io-width = <4>;
>> @@ -73,7 +73,7 @@
>>               compatible = "brcm,bcm11351-dw-apb-uart", "snps,dw-apb-uart";
>>               status = "disabled";
>>               reg = <0x3e003000 0x1000>;
>> -             clock-frequency = <13000000>;
>> +             clocks = <&uartb4_clk>;
>>               interrupts = <GIC_SPI 64 IRQ_TYPE_LEVEL_HIGH>;
>>               reg-shift = <2>;
>>               reg-io-width = <4>;
>> --
>> 1.8.0.1
>>
>>
>>
> --
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