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

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Date:   Mon, 6 Jul 2020 09:17:09 +0530
From:   Anand Moon <linux.amoon@...il.com>
To:     Krzysztof Kozlowski <krzk@...nel.org>
Cc:     linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-samsung-soc@...r.kernel.org,
        Linux Kernel <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

Hi Krzysztof,

Thanks for your review comments.

On Sun, 5 Jul 2020 at 23:32, Krzysztof Kozlowski <krzk@...nel.org> wrote:
>
> 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?
Yes this DEBUG_ATOMIC_SLEEP is enabled in exynos_defconfig.
>
Ok how about the below commit message.

Instead of a busy waiting loop while loop using udelay use readl_poll_timeout
function to check the condition is met or timeout occurs in
crport_handshake function.

> >
> > 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.
Ok thanks
>
> >       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?
I had removed this in this but last minute I added this code again.
>
> Best regards,
> Krzysztof
>

Best Regards
-Anand