Re: [PATCH v8 19/22] counter: Implement extension*_name sysfs attributes
From: William Breathitt Gray
Date: Thu Feb 25 2021 - 18:35:03 EST
On Sun, Feb 21, 2021 at 02:05:07PM +0000, Jonathan Cameron wrote:
>
On 2021年2月19日 17:51:37 +0900
>
William Breathitt Gray <vilhelm.gray@xxxxxxxxx> wrote:
>
>
> On Sun, Feb 14, 2021 at 06:09:13PM +0000, Jonathan Cameron wrote:
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> > On 2021年2月12日 21:13:43 +0900
>
> > William Breathitt Gray <vilhelm.gray@xxxxxxxxx> wrote:
>
> >
>
> > > The Generic Counter chrdev interface expects users to supply extension
>
> > > IDs in order to select extensions for requests. In order for users to
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> > > know what extension ID belongs to which extension this information must
>
> > > be exposed. The extension*_name attribute provides a way for users to
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> > > discover what extension ID belongs to which extension by reading the
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> > > respective extension name for an extension ID.
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> > >
>
> > > Cc: David Lechner <david@xxxxxxxxxxxxxx>
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> > > Cc: Gwendal Grignou <gwendal@xxxxxxxxxxxx>
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> > > Cc: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
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> > > Signed-off-by: William Breathitt Gray <vilhelm.gray@xxxxxxxxx>
>
> > > ---
>
> > > Documentation/ABI/testing/sysfs-bus-counter | 9 ++++
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> > > drivers/counter/counter-sysfs.c | 51 +++++++++++++++++----
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> > > 2 files changed, 50 insertions(+), 10 deletions(-)
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> > >
>
> > > diff --git a/Documentation/ABI/testing/sysfs-bus-counter b/Documentation/ABI/testing/sysfs-bus-counter
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> > > index 6353f0a2f8f8..847e96f19d19 100644
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> > > --- a/Documentation/ABI/testing/sysfs-bus-counter
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> > > +++ b/Documentation/ABI/testing/sysfs-bus-counter
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> > > @@ -100,6 +100,15 @@ Description:
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> > > Read-only attribute that indicates whether excessive noise is
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> > > present at the channel Y counter inputs.
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> > >
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> > > +What: /sys/bus/counter/devices/counterX/countY/extensionZ_name
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> > > +What: /sys/bus/counter/devices/counterX/extensionZ_name
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> > > +What: /sys/bus/counter/devices/counterX/signalY/extensionZ_name
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> > > +KernelVersion: 5.13
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> > > +Contact: linux-iio@xxxxxxxxxxxxxxx
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> > > +Description:
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> > > + Read-only attribute that indicates the component name of
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> > > + Extension Z.
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> >
>
> > Good to say what form this takes.
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>
>
> Do you mean a description like this: "Read-only string attribute that
>
> indicates the component name of Extension Z"?
>
>
My expectation would be that the possible strings are tightly constrained
>
(perhaps via review). So I'd like to see what they are and a brief description
>
of what each one means.
>
>
Jonathan
Okay I see what you mean now. These names will match the sysfs attribute
filenames. So for example, if Extension 9 of Count 2 of Counter device
is /sys/bus/counter/devices/counter4/count2/ceiling, then the attribute
/sys/bus/counter/devices/counter4/count2/extension9_name will hold a
value of "ceiling".
The idea is that the user walks down through each extension*_name to
find sysfs attribute name for the Extension that they want. When they
find the desired Extension name in say sysfs attribute extension9_name,
then they know 9 is the ID number for that Extension.
There is an alternative design I was considering: instead of
extension*_name attributes, we could have each Extension sysfs attribute
have a matching *_extension_id attribute which provides the respective
Extension ID. So for example, using the same Extension as before:
/sys/bus/counter/devices/counter4/count2/ceiling_extension_id will hold
a value of 9.
Do you think this alternative design would be more intuitive to users?
William Breathitt Gray
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