linux-kernel - Re: [PATCH v2] phy: samsung: Use readl_poll

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Date:   Sun, 5 Jul 2020 20:02:48 +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 v2] phy: samsung: Use readl_poll_timeout function

On Sun, Jul 05, 2020 at 06:04:35AM +0000, Anand Moon wrote:
> User readl_poll_timeout function instead of open
> coded handling in crport_handshake function.

Your change does not replace only the "open coded handling" with
readl_poll_timeout(). Your change does more - switches busy waiting with
udelay to a sleeping mode. I am not sure if it is correct but definitly
it should be mentioned.  Otherwise how can we be sure that you checked
if this is allowed in this section? Did you test everything with
DEBUG_ATOMIC_SLEEP?

> 
> Fixes: d8c80bb3b55b ("phy: exynos5-usbdrd: Calibrate LOS levels for exynos5420/5800")
> Signed-off-by: Anand Moon <linux.amoon@...il.com>
> ---
> Changes v2:
> --used the default timeout values.
> --Added missing Fixed tags.
> ---
>  drivers/phy/samsung/phy-exynos5-usbdrd.c | 37 +++++++++---------------
>  1 file changed, 13 insertions(+), 24 deletions(-)
> 
> diff --git a/drivers/phy/samsung/phy-exynos5-usbdrd.c b/drivers/phy/samsung/phy-exynos5-usbdrd.c
> index e510732afb8b..c97f5fb6a9a0 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 +557,28 @@ 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;
> +	u32 timeout_us = 100, sleep_us = 1;

No need for the variables actually and their type does not match. Just
use the values directly.

>  	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), sleep_us, timeout_us);
> +	if (err) {
> +		dev_err(phy_drd->dev, "CRPORT handshake timeout1 (0x%08x)\n", val);
>  		return -ETIME;
>  	}
>  
> -	usec = 100;
> +	timeout_us = 100;
> +	sleep_us = 1;

Why defining then again?

Best regards,
Krzysztof


>  
>  	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), sleep_us, timeout_us);
> +	if (err) {
> +		dev_err(phy_drd->dev, "CRPORT handshake timeout2 (0x%08x)\n", val);
>  		return -ETIME;
>  	}
>  
> -- 
> 2.27.0
>