From: Bjorn Andersson <bjorn.andersson@linaro.org>
To: Fabien Dessenne <fabien.dessenne@st.com>
Cc: Ohad Ben-Cohen <ohad@wizery.com>,
Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Maxime Coquelin <mcoquelin.stm32@gmail.com>,
Alexandre Torgue <alexandre.torgue@st.com>,
Jonathan Corbet <corbet@lwn.net>,
linux-remoteproc@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org,
linux-stm32@st-md-mailman.stormreply.com,
linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org,
Benjamin Gaignard <benjamin.gaignard@st.com>
Subject: Re: [PATCH 0/6] hwspinlock: allow sharing of hwspinlocks
Date: Thu, 1 Aug 2019 12:14:03 -0700 [thread overview]
Message-ID: <20190801191403.GA7234@tuxbook-pro> (raw)
In-Reply-To: <1552492237-28810-1-git-send-email-fabien.dessenne@st.com>
On Wed 13 Mar 08:50 PDT 2019, Fabien Dessenne wrote:
> The current implementation does not allow two different devices to use
> a common hwspinlock. This patch set proposes to have, as an option, some
> hwspinlocks shared between several users.
>
> Below is an example that explain the need for this:
> exti: interrupt-controller@5000d000 {
> compatible = "st,stm32mp1-exti", "syscon";
> interrupt-controller;
> #interrupt-cells = <2>;
> reg = <0x5000d000 0x400>;
> hwlocks = <&hsem 1>;
> };
> The two drivers (stm32mp1-exti and syscon) refer to the same hwlock.
> With the current hwspinlock implementation, only the first driver succeeds
> in requesting (hwspin_lock_request_specific) the hwlock. The second request
> fails.
>
>
> The proposed approach does not modify the API, but extends the DT 'hwlocks'
> property with a second optional parameter (the first one identifies an
> hwlock) that specifies whether an hwlock is requested for exclusive usage
> (current behavior) or can be shared between several users.
> Examples:
> hwlocks = <&hsem 8>; Ref to hwlock #8 for exclusive usage
> hwlocks = <&hsem 8 0>; Ref to hwlock #8 for exclusive (0) usage
> hwlocks = <&hsem 8 1>; Ref to hwlock #8 for shared (1) usage
>
> As a constraint, the #hwlock-cells value must be 1 or 2.
> In the current implementation, this can have theorically any value but:
> - all of the exisiting drivers use the same value : 1.
> - the framework supports only one value : 1 (see implementation of
> of_hwspin_lock_simple_xlate())
> Hence, it shall not be a problem to restrict this value to 1 or 2 since
> it won't break any driver.
>
Hi Fabien,
Your series looks good, but it makes me wonder why the hardware locks
should be an exclusive resource.
How about just making all (specific) locks shared?
Regards,
Bjorn
> Fabien Dessenne (6):
> dt-bindings: hwlock: add support of shared locks
> hwspinlock: allow sharing of hwspinlocks
> dt-bindings: hwlock: update STM32 #hwlock-cells value
> ARM: dts: stm32: Add hwspinlock node for stm32mp157 SoC
> ARM: dts: stm32: Add hwlock for irqchip on stm32mp157
> ARM: dts: stm32: hwlocks for GPIO for stm32mp157
>
> .../devicetree/bindings/hwlock/hwlock.txt | 27 +++++--
> .../bindings/hwlock/st,stm32-hwspinlock.txt | 6 +-
> Documentation/hwspinlock.txt | 10 ++-
> arch/arm/boot/dts/stm32mp157-pinctrl.dtsi | 2 +
> arch/arm/boot/dts/stm32mp157c.dtsi | 10 +++
> drivers/hwspinlock/hwspinlock_core.c | 82 +++++++++++++++++-----
> drivers/hwspinlock/hwspinlock_internal.h | 2 +
> 7 files changed, 108 insertions(+), 31 deletions(-)
>
> --
> 2.7.4
>
next prev parent reply other threads:[~2019-08-01 19:12 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-13 15:50 [PATCH 0/6] hwspinlock: allow sharing of hwspinlocks Fabien Dessenne
2019-03-13 15:50 ` [PATCH 1/6] dt-bindings: hwlock: add support of shared locks Fabien Dessenne
2019-03-28 15:24 ` Rob Herring
2019-03-13 15:50 ` [PATCH 2/6] hwspinlock: allow sharing of hwspinlocks Fabien Dessenne
2019-07-31 9:22 ` Loic PALLARDY
2019-03-13 15:50 ` [PATCH 3/6] dt-bindings: hwlock: update STM32 #hwlock-cells value Fabien Dessenne
2019-03-28 15:26 ` Rob Herring
2019-03-13 15:50 ` [PATCH 4/6] ARM: dts: stm32: Add hwspinlock node for stm32mp157 SoC Fabien Dessenne
2019-03-28 15:26 ` Rob Herring
2019-03-13 15:50 ` [PATCH 5/6] ARM: dts: stm32: Add hwlock for irqchip on stm32mp157 Fabien Dessenne
2019-03-13 15:50 ` [PATCH 6/6] ARM: dts: stm32: hwlocks for GPIO for stm32mp157 Fabien Dessenne
2019-08-01 19:14 ` Bjorn Andersson [this message]
2019-08-05 8:48 ` [PATCH 0/6] hwspinlock: allow sharing of hwspinlocks Fabien DESSENNE
2019-08-05 17:46 ` Bjorn Andersson
2019-08-06 7:43 ` Fabien DESSENNE
2019-08-06 17:38 ` Suman Anna
2019-08-06 18:21 ` Bjorn Andersson
2019-08-06 21:30 ` Suman Anna
2019-08-07 8:39 ` Fabien DESSENNE
2019-08-07 16:19 ` Suman Anna
2019-08-08 12:52 ` Fabien DESSENNE
2019-08-08 15:37 ` Bjorn Andersson
2019-08-26 13:30 ` Fabien DESSENNE
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190801191403.GA7234@tuxbook-pro \
--to=bjorn.andersson@linaro.org \
--cc=alexandre.torgue@st.com \
--cc=benjamin.gaignard@st.com \
--cc=corbet@lwn.net \
--cc=devicetree@vger.kernel.org \
--cc=fabien.dessenne@st.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-doc@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-remoteproc@vger.kernel.org \
--cc=linux-stm32@st-md-mailman.stormreply.com \
--cc=mark.rutland@arm.com \
--cc=mcoquelin.stm32@gmail.com \
--cc=ohad@wizery.com \
--cc=robh+dt@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).