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Date: Mon, 9 Nov 2020 18:32:00 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Cc: Ivan Zaentsev <ivan.zaentsev@...enboard.ru>,
Evgeniy Polyakov <zbr@...emap.net>,
Jonathan Corbet <corbet@....net>,
Akira Shimahara <akira215corp@...il.com>,
Dan Carpenter <dan.carpenter@...cle.com>,
Colin Ian King <colin.king@...onical.com>,
linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
Evgeny Boger <boger@...enboard.com>
Subject: Re: Adding ABI to htmldocs - Was: Re: [PATCH 2/2] w1: w1_therm: Add
support for GXCAS GX20MH01 device.
On Thu, Oct 29, 2020 at 03:28:45PM +0100, Mauro Carvalho Chehab wrote:
> Em Wed, 21 Oct 2020 18:58:19 +0200
> Greg Kroah-Hartman <gregkh@...uxfoundation.org> escreveu:
>
> > On Wed, Oct 21, 2020 at 06:28:43PM +0200, Mauro Carvalho Chehab wrote:
> > > Hi greg,
> > >
> > > Em Wed, 7 Oct 2020 13:59:34 +0200
> > > Mauro Carvalho Chehab <mchehab+huawei@...nel.org> escreveu:
> > >
> > > > Em Wed, 7 Oct 2020 13:43:59 +0200
> > > > Greg Kroah-Hartman <gregkh@...uxfoundation.org> escreveu:
> > > >
> > > > > On Wed, Oct 07, 2020 at 01:05:49PM +0200, Mauro Carvalho Chehab wrote:
> > > > > > Em Wed, 7 Oct 2020 11:06:19 +0200
> > > > > > Greg Kroah-Hartman <gregkh@...uxfoundation.org> escreveu:
> > > > > >
> > > > > > > On Wed, Oct 07, 2020 at 10:57:02AM +0200, Mauro Carvalho Chehab wrote:
> > > > > > > > Em Wed, 7 Oct 2020 10:32:27 +0300
> > > > > > > > Ivan Zaentsev <ivan.zaentsev@...enboard.ru> escreveu:
> > > > > > > >
> > > > > > > > > Tuesday, October 6, 2020, 4:19:15 PM, Mauro Carvalho Chehab wrote:
> > > > > > > > >
> > > > > > > > > >> diff --git a/Documentation/w1/slaves/w1_therm.rst b/Documentation/w1/slaves/w1_therm.rst
> > > > > > > > > >> index f1148181f53e..00376501a5ef 100644
> > > > > > > > > >> --- a/Documentation/w1/slaves/w1_therm.rst
> > > > > > > > > >> +++ b/Documentation/w1/slaves/w1_therm.rst
> > > > > > > > >
> > > > > > > > > >>
> > > > > > > > > >> @@ -130,4 +131,12 @@ conversion and temperature reads 85.00 (powerup value) or 127.94 (insufficient
> > > > > > > > > >> power), the driver returns a conversion error. Bit mask ``2`` enables poll for
> > > > > > > > > >> conversion completion (normal power only) by generating read cycles on the bus
> > > > > > > > > >> after conversion starts. In parasite power mode this feature is not available.
> > > > > > > > > >> -Feature bit masks may be combined (OR).
> > > > > > > > > >> +Feature bit masks may be combined (OR). See accompanying sysfs documentation:
> > > > > > > > > >> +:ref:`Documentation/w1/slaves/w1_therm.rst <w1_therm>`
> > > > > > > > > >> +
> > > > > > > > >
> > > > > > > > > > As warned by Sphinx, this cross-reference is broken:
> > > > > > > > >
> > > > > > > > > > .../Documentation/w1/slaves/w1_therm.rst:125: WARNING:
> > > > > > > > > > undefined label: w1_therm (if the link has no caption the label must precede a section header)
> > > > > > > > >
> > > > > > > > > Would this be ok?
> > > > > > > >
> > > > > > > > Yeah, sure!
> > > > > > > >
> > > > > > > > >
> > > > > > > > > "More details in Documentation/ABI/testing/sysfs-driver-w1_therm"
> > > > > > > > >
> > > > > > > > > > Not sure what you wanted to point here.
> > > > > > > > >
> > > > > > > > > A link to a driver's sysfs interface, but sysfs docs are text
> > > > > > > > > files and seem to not be included in Sphynx Docs.
> > > > > > > >
> > > > > > > > I sent upstream sometime ago a patch series adding ABI to Sphinx, but I
> > > > > > > > was not merged, not sure why:
> > > > > > > >
> > > > > > > > https://git.linuxtv.org/mchehab/experimental.git/log/?h=abi_patches_v5.6
> > > > > > >
> > > > > > > I think the raft of different patches floating around at the time made
> > > > > > > me totally confused as to what was, and was not, the latest versions.
> > > > > >
> > > > > > Yeah, there were lots of patches floating around that time.
> > > > > >
> > > > > > I also recall that someone (Jeni?) asked if the best wouldn't be to
> > > > > > just convert the ABI files to ReST directly.
> > > > > >
> > > > > > > I'll be glad to look at them again, if you want to rebase after 5.10-rc1
> > > > > > > is out and resend them, as I think this should be showing up in the
> > > > > > > documentation.
> > > > > >
> > > > > > Surely. I'll rebase them after 5.10-rc1 and re-submit.
> > > > > >
> > > > > > What strategy do you prefer? Keep the files with the same format as
> > > > > > today (allowing them to optionally have ReST markups) or to convert
> > > > > > them to .rst directly?
> > > > > >
> > > > > > In the latter case, the best would be to apply it as early as possible
> > > > > > after 5.10-rc1, as it may cause conflicts with other patches being
> > > > > > submitted for 5.11.
> > > > >
> > > > > The existing format if at all possible, doing wholesale changes is a
> > > > > mess and wouldn't be recommended.
> > > >
> > > > Yeah, merging it would indeed be a mess. At long term, though, it could
> > > > be easier to maintain.
> > > >
> > > > > I think you already fixed up the entries that had problems being parsed
> > > > > in the past, if not, we can resolve those as well.
> > > >
> > > > Yes. The series start with fixes. I suspect several of them
> > > > (if not all) were already merged, but if anything is missing, I can fix
> > > > at the upcoming rebased series.
> > >
> > > Rebasing the patch series was easier than what I expected:
> > >
> > > https://git.linuxtv.org/mchehab/experimental.git/log/?h=abi_patches_v6
> > >
> > > Yet, while fixing one build issue, I noticed that there are multiple
> > > files defining the same ABI, with different contents.
> > >
> > > Right now, scripts/get_abi.pl assumes that "what" is unique. Well, sorts
> > > of. When it finds a duplicated entry, it merges the description,
> > > preserving the fields from the last parsed entry.
> > >
> > > I ended adding a patch to detect those ABI duplication:
> > >
> > > https://git.linuxtv.org/mchehab/experimental.git/commit/?h=abi_patches_v6&id=6868914605cb0ebffe3fd07d344c246e1e4cd94e
> > >
> > > I'm enclosing the results.
> > >
> > > One such example is this one:
> > >
> > > 3 duplicated entries for /sys/class/leds/<led>/hw_pattern: on file(s) sysfs-class-led-trigger-pattern sysfs-class-led-driver-sc27xx sysfs-class-led-driver-el15203000
> > >
> > > It sounds that different drivers define and use this ABI, but
> > > each one with different meanings.
> > >
> > > There are even some cases where the same file define the same ABI twice:
> > >
> > > 2 duplicated entries for /sys/class/power_supply/<supply_name>/temp_alert_min: on file(s) sysfs-class-power
> > >
> > > Not sure what's the best way to document things like that, or if
> > > the fix would be to drop/merge those.
> > >
> > > Any ideas?
> >
> > We should merge them to be the correct representation. The
> > driver-specific ones for LED should just be dropped to use the
> > class-generic one.
> >
> > I guess just take them one at a time :)
>
> I'm trying to address each one of the duplicated ones...
> I'm now stuck with this one:
>
> At Documentation/ABI/testing/sysfs-driver-w1_therm, it has:
>
> What: /sys/bus/w1/devices/.../eeprom
> Date: May 2020
> Contact: Akira Shimahara <akira215corp@...il.com>
> Description:
> (WO) writing that file will either trigger a save of the
> device data to its embedded EEPROM, either restore data
> embedded in device EEPROM. Be aware that devices support
> limited EEPROM writing cycles (typical 50k)
>
> * 'save': save device RAM to EEPROM
> * 'restore': restore EEPROM data in device RAM
>
> Users: any user space application which wants to communicate with
> w1_term device
>
> Which defines the same ABI as this one:
>
> What: /sys/bus/w1/devices/.../eeprom
> Date: May 2012
> Contact: Markus Franke <franm@....tu-chemnitz.de>
> Description: read/write the contents of the EEPROM memory of the DS28E04-100
> see Documentation/w1/slaves/w1_ds28e04.rst for detailed information
> Users: any user space application which wants to communicate with DS28E04-100
>
> Which is further described at Documentation/w1/slaves/w1_ds28e04.rst:
>
> Memory Access
>
> A read operation on the "eeprom" file reads the given amount of bytes
> from the EEPROM of the DS28E04.
>
> A write operation on the "eeprom" file writes the given byte sequence
> to the EEPROM of the DS28E04. If CRC checking mode is enabled only
> fully aligned blocks of 32 bytes with valid CRC16 values (in bytes 30
> and 31) are allowed to be written.
>
> -
>
> This specific duplication seems very evil, as if someone does:
>
> echo restore > /sys/bus/w1/devices/.../eeprom
>
> and the device is a DS28E04-100, its eeprom will be erased instead
> of being restored!
>
> Not sure how this could be solved without causing regressions.
>
> As the new ABI is from May 2020, added on this commit:
>
> commit 45d457a4cf24455eefd076a01a3d86414fc2ff1e
> Author: Akira Shimahara <akira215corp@...il.com>
> Date: Mon May 11 22:37:25 2020 +0200
>
> w1_therm: adding eeprom sysfs entry
>
> The driver implement 2 hardware functions to access device RAM:
> * copy_scratchpad
> * recall_scratchpad
> They act according to device specifications.
>
> As EEPROM operations are not device dependent (all w1_therm can perform
> EEPROM read/write operation following the same protocol), it is removed
> from device families structures.
>
> Updating Documentation/ABI/testing/sysfs-driver-w1_therm accordingly.
>
> Signed-off-by: Akira Shimahara <akira215corp@...il.com>
> Link: https://lore.kernel.org/r/20200511203725.410844-1-akira215corp@gmail.com
> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
>
> (probably reached Kernel 5.8):
>
> $ git describe 45d457a4cf244
> v5.7-rc5-92-g45d457a4cf24
>
> I guess the solution would be to rename the new one.
We should rename the new one before anyone actually writes any new
userspace code for it.
thanks,
greg k-h
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