Re: [PATCH v4 06/21] PM / devfreq: rockchip-dfi: Use free running counter

From: Sascha Hauer <s.hauer@pengutronix.de>
To: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
	Heiko Stuebner <heiko@sntech.de>,
	linux-rockchip@lists.infradead.org,
	Kyungmin Park <kyungmin.park@samsung.com>,
	MyungJoo Ham <myungjoo.ham@samsung.com>,
	Michael Riesch <michael.riesch@wolfvision.net>,
	kernel@pengutronix.de, Will Deacon <will@kernel.org>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v4 06/21] PM / devfreq: rockchip-dfi: Use free running counter
Date: Wed, 17 May 2023 11:29:57 +0200	[thread overview]
Message-ID: <20230517092957.GU29365@pengutronix.de> (raw)
In-Reply-To: <20230516164843.00000ca5@Huawei.com>

On Tue, May 16, 2023 at 04:48:43PM +0100, Jonathan Cameron wrote:
> On Fri,  5 May 2023 13:38:41 +0200
> Sascha Hauer <s.hauer@pengutronix.de> wrote:
> 
> > The DDR_MON counters are free running counters. These are resetted to 0
> > when starting them over like currently done when reading the current
> > counter values.
> > 
> > Resetting the counters becomes a problem with perf support we want to
> > add later, because perf needs a monotonicly increasing counter.
> 
> In general, perf doesn't, but it does need to know no one else is modifying it,
> so I guess this makes sense.

Makes sense. I'll rephrase that accordingly.

> > @@ -51,7 +55,8 @@ struct dmc_usage {
> >  struct rockchip_dfi {
> >  	struct devfreq_event_dev *edev;
> >  	struct devfreq_event_desc desc;
> > -	struct dmc_usage ch_usage[RK3399_DMC_NUM_CH];
> > +	struct dmc_count count;
> 
> Is count used?  Looking at the code I'd guess you changed to a local variable at
> some point and forgot to drop this.

Yes, exactly. Dropped.

Sascha

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

_______________________________________________
Linux-rockchip mailing list
Linux-rockchip@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-rockchip