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[220.235.124.2]) by smtp.gmail.com with ESMTPSA id x4sm127947pff.143.2019.12.10.15.36.08 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 10 Dec 2019 15:36:11 -0800 (PST) Date: Wed, 11 Dec 2019 07:36:05 +0800 From: Kent Gibson To: Bartosz Golaszewski Cc: Linux Kernel Mailing List , "open list:GPIO SUBSYSTEM" , Bartosz Golaszewski , Linus Walleij , Bamvor Jian Zhang Subject: Re: [PATCH] gpio: gpio-mockup: Fix usage of new GPIO_LINE_DIRECTION Message-ID: <20191210233605.GA4640@sol> References: <20191210021525.13455-1-warthog618@gmail.com> <20191210145515.GB3509@sol> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-gpio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-gpio@vger.kernel.org On Tue, Dec 10, 2019 at 04:34:21PM +0100, Bartosz Golaszewski wrote: > wt., 10 gru 2019 o 15:55 Kent Gibson napisał(a): > > > > On Tue, Dec 10, 2019 at 03:11:12PM +0100, Bartosz Golaszewski wrote: > > > wt., 10 gru 2019 o 03:15 Kent Gibson napisał(a): > > > > > > > > Restore the external behavior of gpio-mockup to what it was prior to the > > > > change to using GPIO_LINE_DIRECTION. > > > > > > > > Signed-off-by: Kent Gibson > > > > --- > > > > > > > > Fix a regression introduced in v5.5-rc1. > > > > > > > > The change to GPIO_LINE_DIRECTION reversed the polarity of the > > > > dir field within gpio-mockup.c, but overlooked inverting the value on > > > > initialization and when returned by gpio_mockup_get_direction. > > > > The latter is a bug. > > > > The former is a problem for tests which assume initial conditions, > > > > specifically the mockup used to initialize chips with all lines as inputs. > > > > That superficially appeared to be the case after the previous patch due > > > > to the bug in gpio_mockup_get_direction. > > > > > > > > drivers/gpio/gpio-mockup.c | 7 +++++-- > > > > 1 file changed, 5 insertions(+), 2 deletions(-) > > > > > > > > diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c > > > > index 56d647a30e3e..c4fdc192ea4e 100644 > > > > --- a/drivers/gpio/gpio-mockup.c > > > > +++ b/drivers/gpio/gpio-mockup.c > > > > @@ -226,7 +226,7 @@ static int gpio_mockup_get_direction(struct gpio_chip *gc, unsigned int offset) > > > > int direction; > > > > > > > > mutex_lock(&chip->lock); > > > > - direction = !chip->lines[offset].dir; > > > > + direction = chip->lines[offset].dir; > > > > mutex_unlock(&chip->lock); > > > > > > > > return direction; > > > > @@ -395,7 +395,7 @@ static int gpio_mockup_probe(struct platform_device *pdev) > > > > struct gpio_chip *gc; > > > > struct device *dev; > > > > const char *name; > > > > - int rv, base; > > > > + int rv, base, i; > > > > u16 ngpio; > > > > > > > > dev = &pdev->dev; > > > > @@ -447,6 +447,9 @@ static int gpio_mockup_probe(struct platform_device *pdev) > > > > if (!chip->lines) > > > > return -ENOMEM; > > > > > > > > + for (i = 0; i < gc->ngpio; i++) > > > > + chip->lines[i].dir = GPIO_LINE_DIRECTION_IN; > > > > + > > > > if (device_property_read_bool(dev, "named-gpio-lines")) { > > > > rv = gpio_mockup_name_lines(dev, chip); > > > > if (rv) > > > > -- > > > > 2.24.0 > > > > > > > > > > Hi Kent, > > > > > > I was applying and testing your libgpiod series and noticed that the > > > gpio-tools tests fail after applying patches 16 & 17 (with linux > > > v5.5-rc1). Is this fix related to this? > > > > > > > I don't think so. I've only been able to trip this problem with a > > couple of corner cases in my Go uapi test suite. > > I have been unable to reproduce it with the tools as it requires > > multiple requests with the same chip fd, including an as-is, to trip. > > > > And running the libgpiod tests against v5.5-rc1 works for me. > > Can you provide more details as to the errors you are seeing? > > > > Hmm whatever that was, it's gone now. Must have been some leftovers > from previous builds. All works now. > > > Btw, I was writing tests for your LINEINFO_WATCH patch v2, which I was > > applying to v5.5-rc1, when I ran across this. That works ok if I > > __packed the changed struct. > > These things can still change, so don't spend too much time on it yet. :) > Absolutely. But as this is an ABI addition I wanted to have something to give it a decent workout before it gets applied. So far the only problems I've found are the alignment and isolation issues already mentioned. > Since the lineinfo struct is not __packed, I'd prefer to not use it > for any struct embedding it. I'll just add appropriate padding for > 64-bit alignment. > Explicit padding for 64-bit alignment makes sense to me. > > And I can confirm that patch v2 doesn't isolate watches on different > > chip fds. > > > > Yeah, I'll fix this. One more thing - since it is possible to lose change events due to fifo overflow, how about adding a seqnum? And if you do end up doing a v2 of the event ABI to fix its alignment, adding one there as well. Kent.