linux-kernel - Re: [PATCH v2 05/17] drm/msm/dpu: Use OPP API to set clk/perf state

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Message-ID: <20200417181724.GE199755@google.com>
Date:   Fri, 17 Apr 2020 11:17:24 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Rajendra Nayak <rnayak@...eaurora.org>
Cc:     viresh.kumar@...aro.org, sboyd@...nel.org,
        bjorn.andersson@...aro.org, agross@...nel.org,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, Rob Clark <robdclark@...il.com>,
        Sean Paul <sean@...rly.run>, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH v2 05/17] drm/msm/dpu: Use OPP API to set clk/perf state

Hi Rajendra,

I have essentially the same comments as for "tty: serial: qcom_geni_serial:
Use OPP API to set clk/perf state" (https://patchwork.kernel.org/patch/11495209/).
about error handling of 'dev_pm_opp_of_add_table' and misleading struct
member names 'opp'/'opp_table'. Please apply the requested changes to the
entire series unless you disagree (we can keep the discussion in the patch
referenced above).

On Fri, Apr 17, 2020 at 07:34:27PM +0530, Rajendra Nayak wrote:
> On some qualcomm platforms DPU needs to express a perforamnce state
> requirement on a power domain depennding on the clock rates.
> Use OPP table from DT to register with OPP framework and use
> dev_pm_opp_set_rate() to set the clk/perf state.
> 
> Signed-off-by: Rajendra Nayak <rnayak@...eaurora.org>
> Cc: Rob Clark <robdclark@...il.com>
> Cc: Sean Paul <sean@...rly.run>
> Cc: dri-devel@...ts.freedesktop.org
> ---
>  drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.c |  3 ++-
>  drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c       | 20 +++++++++++++++++++-
>  drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h       |  4 ++++
>  3 files changed, 25 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.c
> index 11f2beb..fe5717df 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.c
> @@ -7,6 +7,7 @@
>  #include <linux/debugfs.h>
>  #include <linux/errno.h>
>  #include <linux/mutex.h>
> +#include <linux/pm_opp.h>
>  #include <linux/sort.h>
>  #include <linux/clk.h>
>  #include <linux/bitmap.h>
> @@ -239,7 +240,7 @@ static int _dpu_core_perf_set_core_clk_rate(struct dpu_kms *kms, u64 rate)
>  		rate = core_clk->max_rate;
>  
>  	core_clk->rate = rate;
> -	return msm_dss_clk_set_rate(core_clk, 1);
> +	return dev_pm_opp_set_rate(&kms->pdev->dev, core_clk->rate);
>  }
>  
>  static u64 _dpu_core_perf_get_core_clk_rate(struct dpu_kms *kms)
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> index ce19f1d..cfce642 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> @@ -10,6 +10,7 @@
>  #include <linux/debugfs.h>
>  #include <linux/dma-buf.h>
>  #include <linux/of_irq.h>
> +#include <linux/pm_opp.h>
>  
>  #include <drm/drm_crtc.h>
>  #include <drm/drm_file.h>
> @@ -1033,11 +1034,18 @@ static int dpu_bind(struct device *dev, struct device *master, void *data)
>  	if (!dpu_kms)
>  		return -ENOMEM;
>  
> +	dpu_kms->opp = dev_pm_opp_set_clkname(dev, "core");
> +	if (IS_ERR(dpu_kms->opp))
> +		return PTR_ERR(dpu_kms->opp);
> +	/* OPP table is optional */
> +	if (!dev_pm_opp_of_add_table(dev))
> +		dpu_kms->opp_table = true;
> +
>  	mp = &dpu_kms->mp;
>  	ret = msm_dss_parse_clock(pdev, mp);
>  	if (ret) {
>  		DPU_ERROR("failed to parse clocks, ret=%d\n", ret);
> -		return ret;
> +		goto err;
>  	}
>  
>  	platform_set_drvdata(pdev, dpu_kms);
> @@ -1051,6 +1059,11 @@ static int dpu_bind(struct device *dev, struct device *master, void *data)
>  
>  	priv->kms = &dpu_kms->base;
>  	return ret;
> +err:
> +	if (dpu_kms->opp_table)
> +		dev_pm_opp_of_remove_table(dev);
> +	dev_pm_opp_put_clkname(dpu_kms->opp);
> +	return ret;
>  }
>  
>  static void dpu_unbind(struct device *dev, struct device *master, void *data)
> @@ -1059,6 +1072,9 @@ static void dpu_unbind(struct device *dev, struct device *master, void *data)
>  	struct dpu_kms *dpu_kms = platform_get_drvdata(pdev);
>  	struct dss_module_power *mp = &dpu_kms->mp;
>  
> +	if (dpu_kms->opp_table)
> +		dev_pm_opp_of_remove_table(dev);
> +	dev_pm_opp_put_clkname(dpu_kms->opp);
>  	msm_dss_put_clk(mp->clk_config, mp->num_clk);
>  	devm_kfree(&pdev->dev, mp->clk_config);
>  	mp->num_clk = 0;
> @@ -1090,6 +1106,8 @@ static int __maybe_unused dpu_runtime_suspend(struct device *dev)
>  	struct dpu_kms *dpu_kms = platform_get_drvdata(pdev);
>  	struct dss_module_power *mp = &dpu_kms->mp;
>  
> +	/* Drop the performance state vote */
> +	dev_pm_opp_set_rate(dev, 0);
>  	rc = msm_dss_enable_clk(mp->clk_config, mp->num_clk, false);
>  	if (rc)
>  		DPU_ERROR("clock disable failed rc:%d\n", rc);
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
> index 211f5de9..0060709 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
> @@ -128,6 +128,10 @@ struct dpu_kms {
>  
>  	struct platform_device *pdev;
>  	bool rpm_enabled;
> +
> +	struct opp_table *opp;
> +	bool opp_table;
> +
>  	struct dss_module_power mp;
>  
>  	/* reference count bandwidth requests, so we know when we can
> -- 
> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
> of Code Aurora Forum, hosted by The Linux Foundation