linux-kernel - Re: [PATCH 2/2] phy: rockchip-emmc: use regmap_read_poll

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Message-ID: <20180105020749.GA166692@google.com>
Date:   Thu, 4 Jan 2018 18:07:52 -0800
From:   Brian Norris <briannorris@...omium.org>
To:     Shawn Lin <shawn.lin@...k-chips.com>
Cc:     Kishon Vijay Abraham I <kishon@...com>,
        Heiko Stuebner <heiko@...ech.de>,
        Ziyuan Xu <xzy.xu@...k-chips.com>,
        linux-kernel@...r.kernel.org,
        Douglas Anderson <dianders@...omium.org>,
        linux-rockchip@...ts.infradead.org
Subject: Re: [PATCH 2/2] phy: rockchip-emmc: use regmap_read_poll_timeout to
 poll dllrdy

Hi,

On Tue, Jan 02, 2018 at 10:22:00AM +0800, Shawn Lin wrote:
> Just use the API instead of open-coding it, no functional change
> intended.
> 
> Signed-off-by: Shawn Lin <shawn.lin@...k-chips.com>
> ---
> 
>  drivers/phy/rockchip/phy-rockchip-emmc.c | 21 +++++++--------------
>  1 file changed, 7 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/phy/rockchip/phy-rockchip-emmc.c b/drivers/phy/rockchip/phy-rockchip-emmc.c
> index 512a6ef..c65979b 100644
> --- a/drivers/phy/rockchip/phy-rockchip-emmc.c
> +++ b/drivers/phy/rockchip/phy-rockchip-emmc.c
> @@ -79,6 +79,9 @@
>  #define PHYCTRL_IS_CALDONE(x) \
>  	((((x) >> PHYCTRL_CALDONE_SHIFT) & \
>  	  PHYCTRL_CALDONE_MASK) == PHYCTRL_CALDONE_DONE)
> +#define PHYCTRL_IS_DLLRDY(x) \
> +	((((x) >> PHYCTRL_DLLRDY_SHIFT) & \
> +	  PHYCTRL_DLLRDY_MASK) == PHYCTRL_DLLRDY_DONE)
>  
>  struct rockchip_emmc_phy {
>  	unsigned int	reg_offset;
> @@ -93,7 +96,6 @@ static int rockchip_emmc_phy_power(struct phy *phy, bool on_off)
>  	unsigned int dllrdy;
>  	unsigned int freqsel = PHYCTRL_FREQSEL_200M;
>  	unsigned long rate;
> -	unsigned long timeout;
>  
>  	/*
>  	 * Keep phyctrl_pdb and phyctrl_endll low to allow
> @@ -222,19 +224,10 @@ static int rockchip_emmc_phy_power(struct phy *phy, bool on_off)
>  	 *   only at boot / resume.  In both cases, eMMC is probably on the
>  	 *   critical path so busy waiting a little extra time should be OK.

^^ The above comments talk about busy-waiting, keeping this short, and
critical paths. With a sleeping implementation (like
regmap_read_poll_timeout()) that doesn't quite match, does it? I'd think
you might at least change the wording a little to avoid calling it "busy wait".

Brian

>  	 */
> -	timeout = jiffies + msecs_to_jiffies(50);
> -	do {
> -		udelay(1);
> -
> -		regmap_read(rk_phy->reg_base,
> -			rk_phy->reg_offset + GRF_EMMCPHY_STATUS,
> -			&dllrdy);
> -		dllrdy = (dllrdy >> PHYCTRL_DLLRDY_SHIFT) & PHYCTRL_DLLRDY_MASK;
> -		if (dllrdy == PHYCTRL_DLLRDY_DONE)
> -			break;
> -	} while (!time_after(jiffies, timeout));
> -
> -	if (dllrdy != PHYCTRL_DLLRDY_DONE) {
> +	if (regmap_read_poll_timeout(rk_phy->reg_base,
> +				     rk_phy->reg_offset + GRF_EMMCPHY_STATUS,
> +				     dllrdy, PHYCTRL_IS_DLLRDY(dllrdy),
> +				     1, 50 * USEC_PER_MSEC)) {
>  		pr_err("rockchip_emmc_phy_power: dllrdy timeout.\n");
>  		return -ETIMEDOUT;
>  	}