linux-kernel - Re: [PATCH v7 07/26] PM / devfreq: rockchip-dfi: introduce channel mask

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Message-ID: <20231016124558.GL235829@pengutronix.de>
Date:   Mon, 16 Oct 2023 14:45:58 +0200
From:   Sascha Hauer <s.hauer@...gutronix.de>
To:     Chanwoo Choi <chanwoo@...nel.org>
Cc:     linux-rockchip@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, Heiko Stuebner <heiko@...ech.de>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>, kernel@...gutronix.de,
        Michael Riesch <michael.riesch@...fvision.net>,
        Robin Murphy <robin.murphy@....com>,
        Vincent Legoll <vincent.legoll@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>, devicetree@...r.kernel.org,
        Sebastian Reichel <sebastian.reichel@...labora.com>
Subject: Re: [PATCH v7 07/26] PM / devfreq: rockchip-dfi: introduce channel
 mask

On Mon, Oct 16, 2023 at 01:22:16PM +0200, Sascha Hauer wrote:
> On Sat, Oct 07, 2023 at 02:21:10AM +0900, Chanwoo Choi wrote:
> > Hi,
> > 
> > On 23. 7. 4. 18:32, Sascha Hauer wrote:
> > > Different Rockchip SoC variants have a different number of channels.
> > > Introduce a channel mask to make the number of channels configurable
> > > from SoC initialization code.
> > > 
> > > Reviewed-by: Sebastian Reichel <sebastian.reichel@...labora.com>
> > > Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>
> > > ---
> > >  drivers/devfreq/event/rockchip-dfi.c | 23 +++++++++++++++++------
> > >  1 file changed, 17 insertions(+), 6 deletions(-)
> > > 
> > > diff --git a/drivers/devfreq/event/rockchip-dfi.c b/drivers/devfreq/event/rockchip-dfi.c
> > > index 126bb744645b6..82de24a027579 100644
> > > --- a/drivers/devfreq/event/rockchip-dfi.c
> > > +++ b/drivers/devfreq/event/rockchip-dfi.c
> > > @@ -18,10 +18,11 @@
> > >  #include <linux/list.h>
> > >  #include <linux/of.h>
> > >  #include <linux/of_device.h>
> > > +#include <linux/bits.h>
> > >  
> > >  #include <soc/rockchip/rk3399_grf.h>
> > >  
> > > -#define RK3399_DMC_NUM_CH	2
> > > +#define DMC_MAX_CHANNELS	2
> > >  
> > >  /* DDRMON_CTRL */
> > >  #define DDRMON_CTRL	0x04
> > > @@ -44,7 +45,7 @@ struct dmc_count_channel {
> > >  };
> > >  
> > >  struct dmc_count {
> > > -	struct dmc_count_channel c[RK3399_DMC_NUM_CH];
> > > +	struct dmc_count_channel c[DMC_MAX_CHANNELS];
> > >  };
> > >  
> > >  /*
> > > @@ -61,6 +62,7 @@ struct rockchip_dfi {
> > >  	struct regmap *regmap_pmu;
> > >  	struct clk *clk;
> > >  	u32 ddr_type;
> > > +	unsigned int channel_mask;
> > >  };
> > >  
> > >  static void rockchip_dfi_start_hardware_counter(struct devfreq_event_dev *edev)
> > > @@ -95,7 +97,9 @@ static void rockchip_dfi_read_counters(struct devfreq_event_dev *edev, struct dm
> > >  	u32 i;
> > >  	void __iomem *dfi_regs = dfi->regs;
> > >  
> > > -	for (i = 0; i < RK3399_DMC_NUM_CH; i++) {
> > > +	for (i = 0; i < DMC_MAX_CHANNELS; i++) {
> > > +		if (!(dfi->channel_mask & BIT(i)))
> > > +			continue;
> > >  		count->c[i].access = readl_relaxed(dfi_regs +
> > >  				DDRMON_CH0_DFI_ACCESS_NUM + i * 20);
> > >  		count->c[i].total = readl_relaxed(dfi_regs +
> > > @@ -145,9 +149,14 @@ static int rockchip_dfi_get_event(struct devfreq_event_dev *edev,
> > >  	rockchip_dfi_read_counters(edev, &count);
> > >  
> > >  	/* We can only report one channel, so find the busiest one */
> > > -	for (i = 0; i < RK3399_DMC_NUM_CH; i++) {
> > > -		u32 a = count.c[i].access - last->c[i].access;
> > > -		u32 t = count.c[i].total - last->c[i].total;
> > > +	for (i = 0; i < DMC_MAX_CHANNELS; i++) {
> > 
> > Instead of DMC_MAX_CHANNELS defintion,
> > you can initialize the max channel in each rkXXXX_dfi_init() like 'dfi->channel_count'.
> > It reduces the unnecessary loop by initializing the proper max channel.
> 
> That is not easily possible. Some SoCs, eg the RK3588 have four
> channels, but not all channels are necessarily enabled it also
> might not be the first channels that are enabled. On a RK3588
> the channel mask might for example be 0b0101.

Nah, forget this comment. Of course I can initialize a variable with a
maximum value of channels that could be available on this SoC and only
iterate over these. Will do.

Sascha

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