From: Florian Fainelli <f.fainelli@gmail.com>
To: Antoine Tenart <antoine.tenart@bootlin.com>,
davem@davemloft.net, andrew@lunn.ch, hkallweit1@gmail.com
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
alexandre.belloni@bootlin.com, thomas.petazzoni@bootlin.com,
allan.nielsen@microchip.com
Subject: Re: [PATCH net-next 4/4] net: phy: mscc-miim: read poll when high resolution timers are disabled
Date: Tue, 26 May 2020 14:22:31 -0700 [thread overview]
Message-ID: <e95bbdb6-a6db-be02-660e-7318b9bb5f01@gmail.com> (raw)
In-Reply-To: <20200526162256.466885-5-antoine.tenart@bootlin.com>
On 5/26/2020 9:22 AM, Antoine Tenart wrote:
> The driver uses a read polling mechanism to check the status of the MDIO
> bus, to know if it is ready to accept next commands. This polling
> mechanism uses usleep_delay() under the hood between reads which is fine
> as long as high resolution timers are enabled. Otherwise the delays will
> end up to be much longer than expected.
>
> This patch fixes this by using udelay() under the hood when
> CONFIG_HIGH_RES_TIMERS isn't enabled. This increases CPU usage.
>
> Signed-off-by: Antoine Tenart <antoine.tenart@bootlin.com>
> ---
> drivers/net/phy/Kconfig | 3 ++-
> drivers/net/phy/mdio-mscc-miim.c | 22 +++++++++++++++++-----
> 2 files changed, 19 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
> index 2a32f26ead0b..047c27087b10 100644
> --- a/drivers/net/phy/Kconfig
> +++ b/drivers/net/phy/Kconfig
> @@ -184,7 +184,8 @@ config MDIO_MSCC_MIIM
> depends on HAS_IOMEM
> help
> This driver supports the MIIM (MDIO) interface found in the network
> - switches of the Microsemi SoCs
> + switches of the Microsemi SoCs; it is recommended to switch on
> + CONFIG_HIGH_RES_TIMERS
>
> config MDIO_MVUSB
> tristate "Marvell USB to MDIO Adapter"
> diff --git a/drivers/net/phy/mdio-mscc-miim.c b/drivers/net/phy/mdio-mscc-miim.c
> index aed9afa1e8f1..11f583fd4611 100644
> --- a/drivers/net/phy/mdio-mscc-miim.c
> +++ b/drivers/net/phy/mdio-mscc-miim.c
> @@ -39,13 +39,25 @@ struct mscc_miim_dev {
> void __iomem *phy_regs;
> };
>
> +/* When high resolution timers aren't built-in: we can't use usleep_range() as
> + * we would sleep way too long. Use udelay() instead.
> + */
> +#define mscc_readl_poll_timeout(addr, val, cond, delay_us, timeout_us) \
> +({ \
> + if (!IS_ENABLED(CONFIG_HIGH_RES_TIMERS)) \
> + readl_poll_timeout_atomic(addr, val, cond, delay_us, \
> + timeout_us); \
> + readl_poll_timeout(addr, val, cond, delay_us, timeout_us); \
> +})
> +
I would make this a regular function which would not harm the compiler's
ability to optimize it, but would give you type checking. With that fixed:
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
--
Florian
next prev parent reply other threads:[~2020-05-26 21:22 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-26 16:22 [PATCH net-next 0/4] net: phy: mscc-miim: reduce waiting time between MDIO transactions Antoine Tenart
2020-05-26 16:22 ` [PATCH net-next 1/4] net: phy: mscc-miim: use more reasonable delays Antoine Tenart
2020-05-26 21:04 ` Alexandre Belloni
2020-05-26 21:19 ` Florian Fainelli
2020-05-26 16:22 ` [PATCH net-next 2/4] net: phy: mscc-miim: remove redundant timeout check Antoine Tenart
2020-05-26 21:04 ` Alexandre Belloni
2020-05-26 21:19 ` Florian Fainelli
2020-05-26 16:22 ` [PATCH net-next 3/4] net: phy: mscc-miim: improve waiting logic Antoine Tenart
2020-05-26 21:07 ` Alexandre Belloni
2020-05-26 21:21 ` Florian Fainelli
2020-05-26 16:22 ` [PATCH net-next 4/4] net: phy: mscc-miim: read poll when high resolution timers are disabled Antoine Tenart
2020-05-26 21:22 ` Florian Fainelli [this message]
2020-05-26 22:01 ` Andrew Lunn
2020-05-26 22:05 ` Florian Fainelli
2020-05-26 17:01 ` [PATCH net-next 0/4] net: phy: mscc-miim: reduce waiting time between MDIO transactions Andrew Lunn
2020-05-27 7:00 ` Antoine Tenart
2020-05-26 22:34 ` David Miller
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