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Subject: Re: [PATCH v2] drm/lima: add governor data with pre-defined
 thresholds
To:     Christian Hewitt <christianshewitt@gmail.com>,
        Qiang Yu <yuq825@gmail.com>, David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        dri-devel@lists.freedesktop.org, lima@lists.freedesktop.org,
        linux-kernel@vger.kernel.org
Cc:     Steven Price <steven.price@arm.com>
References: <20210127194047.21462-1-christianshewitt@gmail.com>
From:   Lukasz Luba <lukasz.luba@arm.com>
Message-ID: <3ff0efe3-c57a-369c-863a-955004612bda@arm.com>
Date:   Thu, 28 Jan 2021 10:04:50 +0000
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On 1/27/21 7:40 PM, Christian Hewitt wrote:
> This patch adapts the panfrost pre-defined thresholds change [0] to the
> lima driver to improve real-world performance. The upthreshold value has
> been set to ramp GPU frequency to max freq faster (compared to panfrost)
> to compensate for the lower overall performance of utgard devices.
> 
> [0] https://patchwork.kernel.org/project/dri-devel/patch/20210121170445.19761-1-lukasz.luba@arm.com/
> 
> Signed-off-by: Christian Hewitt <christianshewitt@gmail.com>
> ---
> Change since v1: increased upthreshold from 20 to 30, with a soft
> dependency on Lukasz delayed timer patch [0]
> 
> [0] https://lore.kernel.org/lkml/20210127105121.20345-1-lukasz.luba@arm.com/
> 
>   drivers/gpu/drm/lima/lima_devfreq.c | 10 +++++++++-
>   drivers/gpu/drm/lima/lima_devfreq.h |  2 ++
>   2 files changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/lima/lima_devfreq.c b/drivers/gpu/drm/lima/lima_devfreq.c
> index 5686ad4aaf7c..c9854315a0b5 100644
> --- a/drivers/gpu/drm/lima/lima_devfreq.c
> +++ b/drivers/gpu/drm/lima/lima_devfreq.c
> @@ -163,8 +163,16 @@ int lima_devfreq_init(struct lima_device *ldev)
>   	lima_devfreq_profile.initial_freq = cur_freq;
>   	dev_pm_opp_put(opp);
>   
> +	/*
> +	 * Setup default thresholds for the simple_ondemand governor.
> +	 * The values are chosen based on experiments.
> +	 */
> +	ldevfreq->gov_data.upthreshold = 30;
> +	ldevfreq->gov_data.downdifferential = 5;
> +
>   	devfreq = devm_devfreq_add_device(dev, &lima_devfreq_profile,
> -					  DEVFREQ_GOV_SIMPLE_ONDEMAND, NULL);
> +					  DEVFREQ_GOV_SIMPLE_ONDEMAND,
> +					  &ldevfreq->gov_data);
>   	if (IS_ERR(devfreq)) {
>   		dev_err(dev, "Couldn't initialize GPU devfreq\n");
>   		ret = PTR_ERR(devfreq);
> diff --git a/drivers/gpu/drm/lima/lima_devfreq.h b/drivers/gpu/drm/lima/lima_devfreq.h
> index 2d9b3008ce77..b0c7c736e81a 100644
> --- a/drivers/gpu/drm/lima/lima_devfreq.h
> +++ b/drivers/gpu/drm/lima/lima_devfreq.h
> @@ -4,6 +4,7 @@
>   #ifndef __LIMA_DEVFREQ_H__
>   #define __LIMA_DEVFREQ_H__
>   
> +#include <linux/devfreq.h>
>   #include <linux/spinlock.h>
>   #include <linux/ktime.h>
>   
> @@ -18,6 +19,7 @@ struct lima_devfreq {
>   	struct opp_table *clkname_opp_table;
>   	struct opp_table *regulators_opp_table;
>   	struct thermal_cooling_device *cooling;
> +	struct devfreq_simple_ondemand_data gov_data;
>   
>   	ktime_t busy_time;
>   	ktime_t idle_time;
> 

It looks good.

Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>

Regards,
Lukasz