linux-kernel - Re: [PATCH v3] phy: samsung: Use readl_poll

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Date:   Tue, 7 Jul 2020 13:36:45 +0200
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Anand Moon <linux.amoon@...il.com>
Cc:     linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
        Kishon Vijay Abraham I <kishon@...com>,
        Vinod Koul <vkoul@...nel.org>, Kukjin Kim <kgene@...nel.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>
Subject: Re: [PATCH v3] phy: samsung: Use readl_poll_timeout function

On Tue, Jul 07, 2020 at 09:59:08AM +0000, Anand Moon wrote:
> Instead of a busy waiting loop while loop using udelay

You doubled "loop".

> use readl_poll_timeout function to check the condition
> is met or timeout occurs in crport_handshake function.

Still you did not mention that you convert the function to use sleeping
primitive.  You also did not mention whether it is actually allowed in
this context and I am not sure if you investigated it.

Best regards,
Krzysztof

> 
> Fixes: d8c80bb3b55b ("phy: exynos5-usbdrd: Calibrate LOS levels for exynos5420/5800")
> Signed-off-by: Anand Moon <linux.amoon@...il.com>
> ---
> Changes v3:
> --Fix the commit message.
> --Drop the variable, used the value directly.
> Changes v2:
> --used the default timeout values.
> --Added missing Fixed tags.
> ---
>  drivers/phy/samsung/phy-exynos5-usbdrd.c | 35 +++++++-----------------
>  1 file changed, 10 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/phy/samsung/phy-exynos5-usbdrd.c b/drivers/phy/samsung/phy-exynos5-usbdrd.c
> index e510732afb8b..fa75fa88da33 100644
> --- a/drivers/phy/samsung/phy-exynos5-usbdrd.c
> +++ b/drivers/phy/samsung/phy-exynos5-usbdrd.c
> @@ -16,6 +16,7 @@
>  #include <linux/of.h>
>  #include <linux/of_address.h>
>  #include <linux/of_device.h>
> +#include <linux/iopoll.h>
>  #include <linux/phy/phy.h>
>  #include <linux/platform_device.h>
>  #include <linux/mutex.h>
> @@ -556,40 +557,24 @@ static int exynos5_usbdrd_phy_power_off(struct phy *phy)
>  static int crport_handshake(struct exynos5_usbdrd_phy *phy_drd,
>  			    u32 val, u32 cmd)
>  {
> -	u32 usec = 100;
>  	unsigned int result;
> +	int err;
>  
>  	writel(val | cmd, phy_drd->reg_phy + EXYNOS5_DRD_PHYREG0);
>  
> -	do {
> -		result = readl(phy_drd->reg_phy + EXYNOS5_DRD_PHYREG1);
> -		if (result & PHYREG1_CR_ACK)
> -			break;
> -
> -		udelay(1);
> -	} while (usec-- > 0);
> -
> -	if (!usec) {
> -		dev_err(phy_drd->dev,
> -			"CRPORT handshake timeout1 (0x%08x)\n", val);
> +	err = readl_poll_timeout(phy_drd->reg_phy + EXYNOS5_DRD_PHYREG1,
> +			result,	(result & PHYREG1_CR_ACK), 1, 100);
> +	if (err) {
> +		dev_err(phy_drd->dev, "CRPORT handshake timeout1 (0x%08x)\n", val);
>  		return -ETIME;
>  	}
>  
> -	usec = 100;
> -
>  	writel(val, phy_drd->reg_phy + EXYNOS5_DRD_PHYREG0);
>  
> -	do {
> -		result = readl(phy_drd->reg_phy + EXYNOS5_DRD_PHYREG1);
> -		if (!(result & PHYREG1_CR_ACK))
> -			break;
> -
> -		udelay(1);
> -	} while (usec-- > 0);
> -
> -	if (!usec) {
> -		dev_err(phy_drd->dev,
> -			"CRPORT handshake timeout2 (0x%08x)\n", val);
> +	err = readl_poll_timeout(phy_drd->reg_phy + EXYNOS5_DRD_PHYREG1,
> +			result,	!(result & PHYREG1_CR_ACK), 1, 100);
> +	if (err) {
> +		dev_err(phy_drd->dev, "CRPORT handshake timeout2 (0x%08x)\n", val);
>  		return -ETIME;
>  	}
>  
> -- 
> 2.27.0
>