linux-kernel - Re: [PATCH v3 1/5] pwms: pwm-ti*: Remove support for local clock gating

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Message-ID: <20160229220444.GQ13417@atomide.com>
Date:	Mon, 29 Feb 2016 14:04:45 -0800
From:	Tony Lindgren <tony@...mide.com>
To:	Franklin S Cooper Jr <fcooper@...com>
Cc:	paul@...an.com, t-kristo@...com, vigneshr@...com,
	linux-pwm@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-clk@...r.kernel.org
Subject: Re: [PATCH v3 1/5] pwms: pwm-ti*: Remove support for local clock
 gating

* Franklin S Cooper Jr <fcooper@...com> [160225 14:37]:
> The PWMSS local clock gating registers have no real purpose on OMAP ARM
> devices. These registers were left over registers from DSP IP where the
> PRCM doesn't exist. There is a silicon bug where gating and ungating clocks
> don't function properly. TRMs will be update to indicate that these
> registers shouldn't be touched.
> 
> Therefore, all code that accesses the PWMSS_CLKCONFIG or PWMSS_CLKSTATUS
> will be removed by this patch with zero loss of functionality by the ECAP
> and EPWM drivers.
> @@ -243,40 +240,15 @@ static int ecap_pwm_probe(struct platform_device *pdev)
>  	}
>  
>  	pm_runtime_enable(&pdev->dev);
> -	pm_runtime_get_sync(&pdev->dev);
> -
> -	status = pwmss_submodule_state_change(pdev->dev.parent,
> -			PWMSS_ECAPCLK_EN);
> -	if (!(status & PWMSS_ECAPCLK_EN_ACK)) {
> -		dev_err(&pdev->dev, "PWMSS config space clock enable failed\n");
> -		ret = -EINVAL;
> -		goto pwmss_clk_failure;
> -	}
> -
> -	pm_runtime_put_sync(&pdev->dev);
>  
>  	platform_set_drvdata(pdev, pc);
>  	return 0;
> -
> -pwmss_clk_failure:
> -	pm_runtime_put_sync(&pdev->dev);
> -	pm_runtime_disable(&pdev->dev);
> -	pwmchip_remove(&pc->chip);
> -	return ret;
>  }

Hmm but why are you also removing the pm_runtime calls? Those
actually do take care of gating the clocks via the interconnect
level code that is hwmod in this case.

Regards,

Tony