linux-kernel - Re: [PATCH v7 09/26] PM / devfreq: rockchip-dfi: Clean up DDR type register defines

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Message-ID: <1eaa8d5b-af6b-71bb-df7a-d438b483f5bb@kernel.org>
Date:   Sat, 7 Oct 2023 04:11:22 +0900
From:   Chanwoo Choi <chanwoo@...nel.org>
To:     Sascha Hauer <s.hauer@...gutronix.de>,
        linux-rockchip@...ts.infradead.org
Cc:     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 09/26] PM / devfreq: rockchip-dfi: Clean up DDR type
 register defines

On 23. 7. 4. 18:32, Sascha Hauer wrote:
> Use the HIWORD_UPDATE() define known from other rockchip drivers to
> make the defines look less odd to the readers who've seen other
> rockchip drivers.
> 
> The HIWORD registers have their functional bits in the lower 16 bits
> whereas the upper 16 bits contain a mask. Only the functional bits that
> have the corresponding mask bit set are modified during a write. Although
> the register writes look different, the end result should be the same,
> at least there's no functional change intended with this patch.
> 
> Reviewed-by: Sebastian Reichel <sebastian.reichel@...labora.com>
> Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>
> ---
>  drivers/devfreq/event/rockchip-dfi.c | 33 ++++++++++++++++++----------
>  1 file changed, 21 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/devfreq/event/rockchip-dfi.c b/drivers/devfreq/event/rockchip-dfi.c
> index 6bccb6fbcfc0c..6b3ef97b3be09 100644
> --- a/drivers/devfreq/event/rockchip-dfi.c
> +++ b/drivers/devfreq/event/rockchip-dfi.c
> @@ -26,15 +26,19 @@
>  
>  #define DMC_MAX_CHANNELS	2
>  
> +#define HIWORD_UPDATE(val, mask)	((val) | (mask) << 16)
> +
>  /* DDRMON_CTRL */
>  #define DDRMON_CTRL	0x04
> -#define CLR_DDRMON_CTRL	(0x1f0000 << 0)
> -#define LPDDR4_EN	(0x10001 << 4)
> -#define HARDWARE_EN	(0x10001 << 3)
> -#define LPDDR3_EN	(0x10001 << 2)
> -#define SOFTWARE_EN	(0x10001 << 1)
> -#define SOFTWARE_DIS	(0x10000 << 1)
> -#define TIME_CNT_EN	(0x10001 << 0)
> +#define DDRMON_CTRL_DDR4		BIT(5)
> +#define DDRMON_CTRL_LPDDR4		BIT(4)
> +#define DDRMON_CTRL_HARDWARE_EN		BIT(3)
> +#define DDRMON_CTRL_LPDDR23		BIT(2)
> +#define DDRMON_CTRL_SOFTWARE_EN		BIT(1)
> +#define DDRMON_CTRL_TIMER_CNT_EN	BIT(0)
> +#define DDRMON_CTRL_DDR_TYPE_MASK	(DDRMON_CTRL_DDR4 | \
> +					 DDRMON_CTRL_LPDDR4 | \
> +					 DDRMON_CTRL_LPDDR23)
>  
>  #define DDRMON_CH0_COUNT_NUM		0x28
>  #define DDRMON_CH0_DFI_ACCESS_NUM	0x2c
> @@ -73,16 +77,20 @@ static void rockchip_dfi_start_hardware_counter(struct devfreq_event_dev *edev)
>  	void __iomem *dfi_regs = dfi->regs;
>  
>  	/* clear DDRMON_CTRL setting */
> -	writel_relaxed(CLR_DDRMON_CTRL, dfi_regs + DDRMON_CTRL);
> +	writel_relaxed(HIWORD_UPDATE(0, DDRMON_CTRL_TIMER_CNT_EN | DDRMON_CTRL_SOFTWARE_EN |
> +		       DDRMON_CTRL_HARDWARE_EN), dfi_regs + DDRMON_CTRL);

You mentioned that there are no behavior changes even if the different value is written.
But, it looks strange. Could you please explain more detailed about it?


CLR_DDRMON_CTRL is 0x1f0000
vs.
HIWORD_UPDATE(0, DDRMON_CTRL_TIMER_CNT_EN | DDRMON_CTRL_SOFTWARE_EN | DDRMON_CTRL_HARDWARE_EN) = (0 | (BIT(0)|BIT(1)|BIT(3))<<16) = 0xb0000
			
>  
>  	/* set ddr type to dfi */
>  	if (dfi->ddr_type == ROCKCHIP_DDRTYPE_LPDDR3)
> -		writel_relaxed(LPDDR3_EN, dfi_regs + DDRMON_CTRL);
> +		writel_relaxed(HIWORD_UPDATE(DDRMON_CTRL_LPDDR23, DDRMON_CTRL_DDR_TYPE_MASK),
> +			       dfi_regs + DDRMON_CTRL);

LPDDR3_EN	(0x10001 << 2) = 0x40004
vs.
HIWORD_UPDATE(DDRMON_CTRL_LPDDR23, DDRMON_CTRL_DDR_TYPE_MASK) = (BIT(2) | (BIT(5)|BIT(4)|BIT(2))<<16) = 0x340004


>  	else if (dfi->ddr_type == ROCKCHIP_DDRTYPE_LPDDR4)
> -		writel_relaxed(LPDDR4_EN, dfi_regs + DDRMON_CTRL);
> +		writel_relaxed(HIWORD_UPDATE(DDRMON_CTRL_LPDDR4, DDRMON_CTRL_DDR_TYPE_MASK),
> +			       dfi_regs + DDRMON_CTRL);
>  
>  	/* enable count, use software mode */
> -	writel_relaxed(SOFTWARE_EN, dfi_regs + DDRMON_CTRL);
> +	writel_relaxed(HIWORD_UPDATE(DDRMON_CTRL_SOFTWARE_EN, DDRMON_CTRL_SOFTWARE_EN),
> +		       dfi_regs + DDRMON_CTRL);
>  }
>  
>  static void rockchip_dfi_stop_hardware_counter(struct devfreq_event_dev *edev)
> @@ -90,7 +98,8 @@ static void rockchip_dfi_stop_hardware_counter(struct devfreq_event_dev *edev)
>  	struct rockchip_dfi *dfi = devfreq_event_get_drvdata(edev);
>  	void __iomem *dfi_regs = dfi->regs;
>  
> -	writel_relaxed(SOFTWARE_DIS, dfi_regs + DDRMON_CTRL);
> +	writel_relaxed(HIWORD_UPDATE(0, DDRMON_CTRL_SOFTWARE_EN),
> +		       dfi_regs + DDRMON_CTRL);
>  }
>  
>  static void rockchip_dfi_read_counters(struct devfreq_event_dev *edev, struct dmc_count *count)

-- 
Best Regards,
Samsung Electronics
Chanwoo Choi