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Message-ID: <f758b14c5d8343de778f9a6ccdcb29c43778d3f2.camel@perches.com>
Date: Mon, 15 Jul 2019 08:25:01 -0700
From: Joe Perches <joe@...ches.com>
To: Avi Fishman <avifishman70@...il.com>,
Tomer Maimon <tmaimon77@...il.com>,
Tali Perry <tali.perry1@...il.com>,
Patrick Venture <venture@...gle.com>,
Nancy Yuen <yuenn@...gle.com>,
Benjamin Fair <benjaminfair@...gle.com>,
Daniel Lezcano <daniel.lezcano@...aro.org>,
Thomas Gleixner <tglx@...utronix.de>
Cc: OpenBMC Maillist <openbmc@...ts.ozlabs.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] [v2] clocksource/drivers/npcm: fix GENMASK and timer
operation
On Mon, 2019-07-15 at 18:19 +0300, Avi Fishman wrote:
> clocksource/drivers/npcm: fix GENMASK and timer operation
>
> NPCM7XX_Tx_OPER GENMASK() changed from (27, 3) to (28, 27)
>
> in npcm7xx_timer_oneshot() the original NPCM7XX_REG_TCSR0 register was
> read again after masking it with ~NPCM7XX_Tx_OPER so the masking didn't
> take effect.
>
> npcm7xx_timer_periodic() was not wrong but it wrote to NPCM7XX_REG_TICR0
> in a middle of read modify write to NPCM7XX_REG_TCSR0 which is
> confusing.
You might mention how the original use of GENMASK(3, 27)
was defective or correct without effect.
> Signed-off-by: Avi Fishman <avifishman70@...il.com>
> ---
> drivers/clocksource/timer-npcm7xx.c | 9 +++------
> 1 file changed, 3 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/clocksource/timer-npcm7xx.c
> b/drivers/clocksource/timer-npcm7xx.c
> index 8a30da7f083b..9780ffd8010e 100644
> --- a/drivers/clocksource/timer-npcm7xx.c
> +++ b/drivers/clocksource/timer-npcm7xx.c
> @@ -32,7 +32,7 @@
> #define NPCM7XX_Tx_INTEN BIT(29)
> #define NPCM7XX_Tx_COUNTEN BIT(30)
> #define NPCM7XX_Tx_ONESHOT 0x0
> -#define NPCM7XX_Tx_OPER GENMASK(27, 3)
> +#define NPCM7XX_Tx_OPER GENMASK(28, 27)
> #define NPCM7XX_Tx_MIN_PRESCALE 0x1
> #define NPCM7XX_Tx_TDR_MASK_BITS 24
> #define NPCM7XX_Tx_MAX_CNT 0xFFFFFF
> @@ -84,8 +84,6 @@ static int npcm7xx_timer_oneshot(struct
> clock_event_device *evt)
>
> val = readl(timer_of_base(to) + NPCM7XX_REG_TCSR0);
> val &= ~NPCM7XX_Tx_OPER;
> -
> - val = readl(timer_of_base(to) + NPCM7XX_REG_TCSR0);
> val |= NPCM7XX_START_ONESHOT_Tx;
> writel(val, timer_of_base(to) + NPCM7XX_REG_TCSR0);
>
> @@ -97,12 +95,11 @@ static int npcm7xx_timer_periodic(struct
> clock_event_device *evt)
> struct timer_of *to = to_timer_of(evt);
> u32 val;
>
> + writel(timer_of_period(to), timer_of_base(to) + NPCM7XX_REG_TICR0);
> +
> val = readl(timer_of_base(to) + NPCM7XX_REG_TCSR0);
> val &= ~NPCM7XX_Tx_OPER;
> -
> - writel(timer_of_period(to), timer_of_base(to) + NPCM7XX_REG_TICR0);
> val |= NPCM7XX_START_PERIODIC_Tx;
> -
> writel(val, timer_of_base(to) + NPCM7XX_REG_TCSR0);
>
> return 0;
>
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