From: Linus Walleij <linus.walleij@linaro.org>
To: timur@kernel.org
Cc: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>,
Stephen Boyd <swboyd@chromium.org>,
"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] gpiolib: Show correct direction from the beginning
Date: Fri, 21 Sep 2018 09:07:38 -0700 [thread overview]
Message-ID: <CACRpkdYV+A9rUZvYN_Vh3wD6Vb73qj8=SkHJCJ0ZiTWP5Ojw1A@mail.gmail.com> (raw)
In-Reply-To: <27c8e13a-44bf-18b5-083b-25b87d7b8605@kernel.org>
On Thu, Sep 20, 2018 at 7:05 PM Timur Tabi <timur@kernel.org> wrote:
> On 9/20/18 5:36 PM, Linus Walleij wrote:
> > What I mean is that $SUBJECT patch might not hurt Qualcomms
> > GPIOs (not crash the platform) if and only if it is augmented to not
> > try to get the initial direction from lines masked off in .valid_mask
> > if .need_valid_mask is true.
> >
> > Whether it makes sense semantically is a different debate, but it
> > seems possible to reintroduce calling .get_direction() without
> > hurting anyone.
>
> That means that all the logic for checking valid_mask needs to be added
> to the chip driver's .get_direction() function. We can add that logic
> to msm_gpio_get_direction (at one point, I had a patch that did that,
> but it was rejected).
Nah, what is in patch v2 is better, just checking it when we need to.
> My concern is: what if a driver depends on a .request call being made
> (in order to configure muxes, for example) before touching the hardware?
Hm. That is a good question.
I wonder if we have that problem in practice. If this happens, maybe the
driver needs to keep track of stuff a bit. I think if we just loop request
over everything we could disturb other mux set-up.
> I wonder if this is something that really should be handled in the
> driver's .probe function. The driver should collect that information
> and pass it to add_data.
I see the idea, but it seems complicated compared to just calling
the callbacks. Let's try the v2 patch approach first.
Yours,
Linus Walleij
prev parent reply other threads:[~2018-09-21 16:07 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-14 7:08 [RFC] gpiolib: Fix gpio_direction_* for single direction GPIOs Ricardo Ribalda Delgado
2018-09-14 7:08 ` [PATCH] gpiolib: Show correct direction from the beginning Ricardo Ribalda Delgado
2018-09-18 22:40 ` Linus Walleij
2018-09-19 4:04 ` Ricardo Ribalda Delgado
2018-09-19 11:50 ` Timur Tabi
2018-09-19 15:27 ` Ricardo Ribalda Delgado
2018-09-20 12:20 ` Timur Tabi
2018-09-20 14:14 ` Ricardo Ribalda Delgado
2018-09-20 22:43 ` Linus Walleij
2018-09-20 12:25 ` Timur Tabi
2018-09-20 5:23 ` Linus Walleij
2018-09-20 12:35 ` Timur Tabi
2018-09-20 22:36 ` Linus Walleij
2018-09-21 2:05 ` Timur Tabi
2018-09-21 16:07 ` Linus Walleij [this message]
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