From: Wolfram Sang <wsa+renesas@sang-engineering.com>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: "open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linus Walleij <linus.walleij@linaro.org>
Subject: Re: [PATCH 1/1] gpio: add sloppy logic analyzer using polling
Date: Mon, 6 Sep 2021 11:04:00 +0200 [thread overview]
Message-ID: <YTXZgNQJj0aI4zuC@kunai> (raw)
In-Reply-To: <CAHp75VdZt_dDb0YpThfsoqRvWdjfVZT70o=eCJCbThJ9qbD42w@mail.gmail.com>
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Hi Andy,
thank you for the review again!
> > + unsigned long state = 0; /* zeroed because GPIO arrays are bitfields */
>
> Not sure if bitmap_zero() would be better. Up to you.
Looks cleaner, I'll check.
> > +static int fops_buf_size_set(void *data, u64 val)
> > +{
> > + struct gpio_la_poll_priv *priv = data;
> > + int ret = 0;
> > + void *p;
> > +
> > + if (!val)
>
> > + return -EINVAL;
>
> Hmm... in this case you haven't updated the internal parameters, but...
>
> > + mutex_lock(&priv->lock);
> > +
> > + vfree(priv->blob.data);
> > + p = vzalloc(val);
> > + if (!p) {
> > + val = 0;
> > + ret = -ENOMEM;
>
> ...here you do. What's the difference?
vfree(). In the latter case, the old buffer is already gone.
> > + if (ret >= 0 && ret != priv->descs->ndescs)
>
> > + ret = -ENOSTR;
>
> A bit of an unusual error code.
> Perhaps -ENODATA?
OK, as long as it is unique...
> > + /* '10' is length of 'probe00=\n\0' */
>
> Maybe instead of comment is to use respective strlen():s / sizeof():s?
>
> Actually, looking below possible option is
>
> const char *fmt = "probe...";
>
> add_len += sprintf(NULL, 0, fmt, 0, "");
>
> ...
>
> snprintf(..., fmt, ...);
>
> But it's up to you.
>
> > + add_len = strlen(gpio_names[i]) + 10;
> > +
> > + new_meta = devm_krealloc(dev, meta, meta_len + add_len, GFP_KERNEL);
> > + if (!new_meta)
> > + return -ENOMEM;
> > +
> > + meta = new_meta;
> > + snprintf(meta + meta_len, add_len, "probe%02d=%s\n", i + 1, gpio_names[i]);
>
> > + /* ' - 1' to skip the NUL terminator */
> > + meta_len += add_len - 1;
>
> Reuse return value from snprintf()?
I will have a look at these string refactorings when I need the analyzer
next time and come back then.
>
> > + }
>
> ...
>
> > +static int gpio_la_poll_remove(struct platform_device *pdev)
> > +{
> > + struct gpio_la_poll_priv *priv = platform_get_drvdata(pdev);
> > +
> > + mutex_lock(&priv->lock);
> > + debugfs_remove_recursive(priv->debug_dir);
> > + mutex_unlock(&priv->lock);
>
> mutex_destroy()?
Oh yes, thank you!
>
> > +
> > + return 0;
> > +}
>
> ...
>
> > +#!/bin/sh -eu
>
> Next step is to add 'f' to the mix here :-)
-f broke zip file generation in a way I didn't know how to resolve
differently. Sadly, I can't recall the details right now.
>
> ...
>
> > +$0 - helper script for the Linux Kernel Sloppy GPIO Logic Analyzer
>
> Use at the top something like
>
> PROG_NAME="${0##*/}"
I like this!
> echo "$2'
> exit $1
I don't see the need now. We can update if we need it.
> > + [ -n "$cur_cpu" ] && fail "CPU$isol_cpu requested but CPU$cur_cpu already isolated"
>
> This theoretically may fail the script since you have '-e'.
> I guess I have mentioned that 'a && b' is not an equivalent to 'if-then-fi'.
> I suggest double checking all similar expressions and try under
> different shells (like dash).
Well, from the cover-letter:
* A *lot* of cleanups to the shell script guided by checkers, mainly
'shellcheck'. This is mainly to ensure that the scripts works on most
minimal shells. Tested are 'busybox ash', 'dash', and 'bash'.
> > + [ -w "$cpufreqgov" ] && echo 'performance' > "$cpufreqgov" || true
>
> I guess this is where you actually hit the above mentioned difference.
I used a different kernel on a different SoC which did not have CPUfreq
at all.
>
> ...
>
> > +while true; do
> > + case "$1" in
> > + -c|--cpu) initcpu="$2"; shift 2;;
> > + -d|--duration-us) duration="$2"; shift 2;;
> > + -h|--help) print_help; exit 0;;
> > + -i|--instance) lasysfsdir="$sysfsdir/$2"; shift 2;;
> > + -k|--kernel-debug-dir) debugdir="$2"; shift 2;;
> > + -n|--num_samples) numsamples="$2"; shift 2;;
> > + -o|--output-dir) outputdir="$2"; shift 2;;
> > + -s|--sample_freq) samplefreq="$2"; shift 2;;
> > + -t|--trigger) triggerdat="$2"; shift 2;;
> > + --) shift; break;;
> > + *) fail "error parsing commandline: $*";;
> > + esac
>
> I would prefer to have a clear shift here instead of doing shift 2
> everywhere above (less error prone).
If we ever support binary arguments (toggles), then a generic 'shift 2'
won't work?
>
> > +done
>
> ...
>
> I think usage of SI units makes sense to be less error prone in case
> you are using them more than once.
SI would be useful, for sure. But I need to move on right now, so it
needs to be done incrementally.
All the best,
Wolfram
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next prev parent reply other threads:[~2021-09-06 9:04 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-01 19:45 [PATCH 0/1] gpio: add simple logic analyzer using polling Wolfram Sang
2021-09-01 19:45 ` [PATCH 1/1] gpio: add sloppy " Wolfram Sang
2021-09-05 11:20 ` Andy Shevchenko
2021-09-06 9:04 ` Wolfram Sang [this message]
2021-09-06 10:15 ` Andy Shevchenko
2021-09-06 12:21 ` Wolfram Sang
[not found] ` <CAHp75VdNnvUfMEL3gMrJOFix3AATL8LAiU18LXJJVL77feBRow@mail.gmail.com>
2021-09-06 7:38 ` Wolfram Sang
2021-09-06 7:47 ` Andy Shevchenko
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