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Message-ID: <642a376532b26_394c3829466@iweiny-mobl.notmuch>
Date: Sun, 2 Apr 2023 19:18:13 -0700
From: Ira Weiny <ira.weiny@...el.com>
To: Dan Carpenter <error27@...il.com>,
Khadija Kamran <kamrankhadijadj@...il.com>
CC: <outreachy@...ts.linux.dev>, <hvaibhav.linux@...il.com>,
<johan@...nel.org>, <elder@...nel.org>,
<gregkh@...uxfoundation.org>, <greybus-dev@...ts.linaro.org>,
<linux-staging@...ts.linux.dev>, <linux-kernel@...r.kernel.org>,
Alison Schofield <alison.schofield@...el.com>
Subject: Re: [PATCH 2/2] staging: greybus: refactor arche_platform_wd_irq()
Dan Carpenter wrote:
> On Thu, Mar 30, 2023 at 07:11:25PM +0500, Khadija Kamran wrote:
> > Linux kernel coding-style suggests to fix your program if it needs more
> > than 3 levels of indentation. Due to indentation, line length also
> > exceeds 100 columns, resulting in issues reported by checkpatch.
> >
> > Refactor the arche_platform_wd_irq() function and reduce the indentation
> > with the help of goto statement.
> >
> > Suggested-by: Alison Schofield <alison.schofield@...el.com>
> > Signed-off-by: Khadija Kamran <kamrankhadijadj@...il.com>
> > ---
> > drivers/staging/greybus/arche-platform.c | 79 ++++++++++++------------
> > 1 file changed, 41 insertions(+), 38 deletions(-)
> >
> > diff --git a/drivers/staging/greybus/arche-platform.c b/drivers/staging/greybus/arche-platform.c
> > index a64c1af091b0..dde30c8da1a1 100644
> > --- a/drivers/staging/greybus/arche-platform.c
> > +++ b/drivers/staging/greybus/arche-platform.c
> > @@ -158,49 +158,52 @@ static irqreturn_t arche_platform_wd_irq(int irq, void *devid)
> >
> > spin_lock_irqsave(&arche_pdata->wake_lock, flags);
> >
> > - if (gpiod_get_value(arche_pdata->wake_detect)) {
> > - /* wake/detect rising */
> > + if (!gpiod_get_value(arche_pdata->wake_detect))
> > + goto falling;
I don't like this negative logic here. Can't this be handled with
positive logic?
> >
> > + /* wake/detect rising */
> > +
> > + /*
> > + * If wake/detect line goes high after low, within less than
> > + * 30msec, then standby boot sequence is initiated, which is not
> > + * supported/implemented as of now. So ignore it.
> > + */
> > + if (arche_pdata->wake_detect_state != WD_STATE_BOOT_INIT)
> > + goto out;
>
> This checks that we are in WD_STATE_BOOT_INIT state.
Doesn't this check we are _not_ in WD_STATE_BOOT_INIT?
>
> > +
> > + if (time_before(jiffies,
> > + arche_pdata->wake_detect_start +
> > + msecs_to_jiffies(WD_COLDBOOT_PULSE_WIDTH_MS))) {
> > + arche_platform_set_wake_detect_state(arche_pdata,
> > + WD_STATE_IDLE);
> > + got out;
> > + }
> > +
> > + /* Check we are not in middle of irq thread already */
> > + if (arche_pdata->wake_detect_state !=
> > + WD_STATE_COLDBOOT_START) {
>
> This checks that we are not in WD_STATE_COLDBOOT_START state. How are
> we going to be in COLDBOOT if we are in INIT? Is this changing in the
> background? Can this check be removed? This might be took tricky to
> answer but it's important that we understand this before we continue.
>
>
> > + arche_platform_set_wake_detect_state(arche_pdata,
> > + WD_STATE_COLDBOOT_TRIG);
> > + rc = IRQ_WAKE_THREAD;
> > + goto out;
> > + }
>
> Let's assume the above check cannot be removed.
>
> In the original code if gpiod_get_value(arche_pdata->wake_detect)
> returned true and arche_pdata->wake_detect_state == WD_STATE_IDLE then
> it just returned without doing anything, but now we fall through to the
> falling: label below.
I don't believe we do. But I think the proposed logic does make this
difficult to detect.
Ira
>
> So this patch seems like it introduces a bug, but actually it might just
> have a dead code problem.
>
> regards,
> dan carpenter
>
> > +
> > +falling:
> > + /* wake/detect falling */
> > + if (arche_pdata->wake_detect_state == WD_STATE_IDLE) {
> > + arche_pdata->wake_detect_start = jiffies;
> > /*
> > - * If wake/detect line goes high after low, within less than
> > - * 30msec, then standby boot sequence is initiated, which is not
> > - * supported/implemented as of now. So ignore it.
> > + * In the beginning, when wake/detect goes low
> > + * (first time), we assume it is meant for coldboot
> > + * and set the flag. If wake/detect line stays low
> > + * beyond 30msec, then it is coldboot else fallback
> > + * to standby boot.
> > */
> > - if (arche_pdata->wake_detect_state == WD_STATE_BOOT_INIT) {
> > - if (time_before(jiffies,
> > - arche_pdata->wake_detect_start +
> > - msecs_to_jiffies(WD_COLDBOOT_PULSE_WIDTH_MS))) {
> > - arche_platform_set_wake_detect_state(arche_pdata,
> > - WD_STATE_IDLE);
> > - } else {
> > - /*
> > - * Check we are not in middle of irq thread
> > - * already
> > - */
> > - if (arche_pdata->wake_detect_state !=
> > - WD_STATE_COLDBOOT_START) {
> > - arche_platform_set_wake_detect_state(arche_pdata,
> > - WD_STATE_COLDBOOT_TRIG);
> > - rc = IRQ_WAKE_THREAD;
> > - }
> > - }
> > - }
> > - } else {
> > - /* wake/detect falling */
> > - if (arche_pdata->wake_detect_state == WD_STATE_IDLE) {
> > - arche_pdata->wake_detect_start = jiffies;
> > - /*
> > - * In the beginning, when wake/detect goes low
> > - * (first time), we assume it is meant for coldboot
> > - * and set the flag. If wake/detect line stays low
> > - * beyond 30msec, then it is coldboot else fallback
> > - * to standby boot.
> > - */
> > - arche_platform_set_wake_detect_state(arche_pdata,
> > - WD_STATE_BOOT_INIT);
> > - }
> > + arche_platform_set_wake_detect_state(arche_pdata,
> > + WD_STATE_BOOT_INIT);
> > }
> >
> > +out:
> > spin_unlock_irqrestore(&arche_pdata->wake_lock, flags);
> >
> > return rc;
> > --
> > 2.34.1
> >
>
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