linux-kernel - Re: [PATCH v4] phy: samsung: Use readl_poll

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Date:   Thu, 16 Jul 2020 11:20:50 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     Anand Moon <linux.amoon@...il.com>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-usb@...r.kernel.org,
        linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
        Kishon Vijay Abraham I <kishon@...com>,
        Kukjin Kim <kgene@...nel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>
Subject: Re: [PATCH v4] phy: samsung: Use readl_poll_timeout function

On 13-07-20, 07:42, Anand Moon wrote:
> Instead of a busy waiting while loop using udelay
> use readl_poll_timeout function to check the condition
> is met or timeout occurs in crport_handshake function.
> readl_poll_timeout is called in non atomic context so
> it safe to sleep until the condition is met.
> 
> Fixes: d8c80bb3b55b ("phy: exynos5-usbdrd: Calibrate LOS levels for exynos5420/5800")
> Signed-off-by: Anand Moon <linux.amoon@...il.com>
> ---
> Changes v4:
> Rebased on to of patch [0] https://patchwork.kernel.org/patch/11651673/
> --Fix the commit message.
> --Fix the error timeout condition for -ETIMEDOUT
> ---
> 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 | 39 ++++++++----------------
>  1 file changed, 12 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/phy/samsung/phy-exynos5-usbdrd.c b/drivers/phy/samsung/phy-exynos5-usbdrd.c
> index 7f6279fb4f8f..ad81aa65cdff 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>
> @@ -556,41 +557,25 @@ 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);
> -		return -ETIME;
> +	err = readl_poll_timeout(phy_drd->reg_phy + EXYNOS5_DRD_PHYREG1,
> +			result,	(result & PHYREG1_CR_ACK), 1, 100);

pls align this line to opening brace of preceding line:

        err = readl_poll_timeout(phy_drd->reg_phy + EXYNOS5_DRD_PHYREG1,
                                 result, (result & PHYREG1_CR_ACK), 1, 100);

This is recommended way of splitting lines, see
Documentation/process/coding-style.rst and run checkpatch.pl with
--strict option

thanks
-- 
~Vinod