linux-kernel - Re: [PATCH v2 3/4] clk: qcom: ipq5332: Use icc-clk for enabling NoC related clocks

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Message-ID: <iwdennlw4njxefulw5e2wofu4pylep65el4hiiso6xqmoaq5fb@i4hrltrn2o6z>
Date: Sat, 13 Jul 2024 19:21:29 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Varadarajan Narayanan <quic_varada@...cinc.com>
Cc: andersson@...nel.org, mturquette@...libre.com, sboyd@...nel.org, 
	robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org, 
	gregkh@...uxfoundation.org, konrad.dybcio@...aro.org, djakov@...nel.org, 
	quic_wcheng@...cinc.com, linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org, 
	linux-pm@...r.kernel.org
Subject: Re: [PATCH v2 3/4] clk: qcom: ipq5332: Use icc-clk for enabling NoC
 related clocks

On Thu, Jul 11, 2024 at 05:02:38PM GMT, Varadarajan Narayanan wrote:
> Use the icc-clk framework to enable few clocks to be able to
> create paths and use the peripherals connected on those NoCs.
> 
> Signed-off-by: Varadarajan Narayanan <quic_varada@...cinc.com>
> ---
>  drivers/clk/qcom/gcc-ipq5332.c | 36 +++++++++++++++++++++++++++++-----
>  1 file changed, 31 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/clk/qcom/gcc-ipq5332.c b/drivers/clk/qcom/gcc-ipq5332.c
> index f98591148a97..6d7672cae0f7 100644
> --- a/drivers/clk/qcom/gcc-ipq5332.c
> +++ b/drivers/clk/qcom/gcc-ipq5332.c
> @@ -4,12 +4,14 @@
>   */
>  
>  #include <linux/clk-provider.h>
> +#include <linux/interconnect-provider.h>
>  #include <linux/mod_devicetable.h>
>  #include <linux/module.h>
>  #include <linux/platform_device.h>
>  #include <linux/regmap.h>
>  
>  #include <dt-bindings/clock/qcom,ipq5332-gcc.h>
> +#include <dt-bindings/interconnect/qcom,ipq5332.h>
>  
>  #include "clk-alpha-pll.h"
>  #include "clk-branch.h"
> @@ -131,12 +133,14 @@ static struct clk_alpha_pll gpll4_main = {
>  			 * (will be added soon), so the clock framework
>  			 * disables this source. But some of the clocks
>  			 * initialized by boot loaders uses this source. So we
> -			 * need to keep this clock ON. Add the
> -			 * CLK_IGNORE_UNUSED flag so the clock will not be
> -			 * disabled. Once the consumer in kernel is added, we
> -			 * can get rid of this flag.
> +			 * need to keep this clock ON.
> +			 *
> +			 * After initial bootup, when the ICC framework turns
> +			 * off unused paths, as part of the icc-clk dependencies
> +			 * this clock gets disabled resulting in a hang. Marking
> +			 * it as critical to ensure it is not turned off.

Previous comment was pretty clear: there are missing consumers, the flag
will be removed once they are added. Current comment doesn't make sense.
What is the reason for the device hang if we have all the consumers in
place?

>  			 */
> -			.flags = CLK_IGNORE_UNUSED,
> +			.flags = CLK_IS_CRITICAL,
>  		},
>  	},
>  };


-- 
With best wishes
Dmitry