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Date:   Wed, 31 May 2023 12:43:48 +0200
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Subject: Re: [PATCH v4 0/9] serial: sc16is7xx: fix GPIO regression and rs485
 improvements
To:     Hugo Villeneuve <hugo@hugovil.com>
CC:     gregkh@linuxfoundation.org, robh+dt@kernel.org,
        krzysztof.kozlowski+dt@linaro.org, conor+dt@kernel.org,
        jirislaby@kernel.org, jringle@gridpoint.com,
        l.perczak@camlintechnologies.com, tomasz.mon@camlingroup.com,
        linux-serial@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-gpio@vger.kernel.org,
        Hugo Villeneuve <hvilleneuve@dimonoff.com>
References: <20230529140711.896830-1-hugo@hugovil.com>
 <c15a90d6-b3c1-e432-9216-c4c1e2c44ce6@camlingroup.com>
 <20230530090836.27b8d080d6b6c022b303ac9e@hugovil.com>
From:   Lech Perczak <lech.perczak@camlingroup.com>
In-Reply-To: <20230530090836.27b8d080d6b6c022b303ac9e@hugovil.com>
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W dniu 30.05.2023 o=C2=A015:08, Hugo Villeneuve pisze:
> On Tue, 30 May 2023 11:30:07 +0200
> Lech Perczak <lech.perczak@camlingroup.com> wrote:
>
> > W dniu 29.05.2023 o=C2=A016:07, Hugo Villeneuve pisze:
> > > From: Hugo Villeneuve <hvilleneuve@dimonoff.com>
> > >
> > > Hello,
> > > this patch series mainly fixes a GPIO regression and improve RS485 fl=
ags and
> > > properties detection from DT.
> > >
> > > It now also includes various small fixes and improvements that were p=
reviously
> > > sent as separate patches, but that made testing everything difficult.
> > >
> > > Patch 1 fixes an issue when debugging IOcontrol register. After testi=
ng the GPIO
> > > regression patches (patches 6 and 7, tests done by Lech Perczak), it =
appers that
> > > this patch is also necessary for having the correct IOcontrol registe=
r values.
> > >
> > > Patch 2 introduces a delay after a reset operation to respect datashe=
et
> > > timing recommandations.
> > >
> > > Patch 3 fixes an issue with init of first port during probing.
> > >
> > > Patch 4 fixes a bug with the output value when first setting the GPIO=
 direction.
> > >
> > > Patch 5 is a refactor of GPIO registration code.
> > >
> > > Patches 6 and 7 fix a GPIO regression by (re)allowing to choose GPIO =
function
> > > for GPIO pins shared with modem status lines.
> > >
> > > Patch 8 allows to read common rs485 device-tree flags and properties.
> > >
> > > Patch 9 improves comments about chip variants.
> > >
> > > I have tested the changes on a custom board with two SC16IS752 DUART =
using a
> > > Variscite IMX8MN NANO SOM.
> > >
> > > Thank you.
> > >
> > > Link: [v1] https://lkml.org/lkml/2023/5/17/967 <https://lkml.org/lkml=
/2023/5/17/967> <https://lkml.org/lkml/2023/5/17/967 <https://lkml.org/lkml=
/2023/5/17/967>>
> > > [v1] https://lkml.org/lkml/2023/5/17/777 <https://lkml.org/lkml/2023/=
5/17/777> <https://lkml.org/lkml/2023/5/17/777 <https://lkml.org/lkml/2023/=
5/17/777>>
> > > [v1] https://lkml.org/lkml/2023/5/17/780 <https://lkml.org/lkml/2023/=
5/17/780> <https://lkml.org/lkml/2023/5/17/780 <https://lkml.org/lkml/2023/=
5/17/780>>
> > > [v1] https://lkml.org/lkml/2023/5/17/785 <https://lkml.org/lkml/2023/=
5/17/785> <https://lkml.org/lkml/2023/5/17/785 <https://lkml.org/lkml/2023/=
5/17/785>>
> > > [v1] https://lkml.org/lkml/2023/5/17/1311 <https://lkml.org/lkml/2023=
/5/17/1311> <https://lkml.org/lkml/2023/5/17/1311 <https://lkml.org/lkml/20=
23/5/17/1311>>
> > > [v2] https://lkml.org/lkml/2023/5/18/516 <https://lkml.org/lkml/2023/=
5/18/516> <https://lkml.org/lkml/2023/5/18/516 <https://lkml.org/lkml/2023/=
5/18/516>>
> > > [v3] https://lkml.org/lkml/2023/5/25/7 <https://lkml.org/lkml/2023/5/=
25/7> <https://lkml.org/lkml/2023/5/25/7 <https://lkml.org/lkml/2023/5/25/7=
>>
> > >
> > > Changes for V3:
> > > - Integrated all patches into single serie to facilitate debugging an=
d tests.
> > > - Reduce number of exported GPIOs depending on new property
> > > nxp,modem-control-line-ports
> > > - Added additional example in DT bindings
> > >
> > > Changes for V4:
> > > - Increase reset post delay to relax scheduler.
> > > - Put comments patches at the end.
> > > - Remove Fixes tag for patch "mark IOCONTROL register as volatile".
> > > - Improve commit messages after reviews.
> > > - Fix coding style issues after reviews.
> > > - Change GPIO registration to always register the maximum number of G=
PIOs
> > > supported by the chip, but maks-out GPIOs declared as modem control l=
ines.
> > > - Add patch to refactor GPIO registration.
> > > - Remove patch "serial: sc16is7xx: fix syntax error in comments".
> > > - Remove patch "add dump registers function"
> > >
> > > Hugo Villeneuve (9):
> > > serial: sc16is7xx: mark IOCONTROL register as volatile
> > > serial: sc16is7xx: add post reset delay
> > > serial: sc16is7xx: fix broken port 0 uart init
> > > serial: sc16is7xx: fix bug when first setting GPIO direction
> > > serial: sc16is7xx: refactor GPIO controller registration
> > > dt-bindings: sc16is7xx: Add property to change GPIO function
> > > serial: sc16is7xx: fix regression with GPIO configuration
> > > serial: sc16is7xx: add call to get rs485 DT flags and properties
> > > serial: sc16is7xx: improve comments about variants
> > >
> > > .../bindings/serial/nxp,sc16is7xx.txt | 46 ++++++
> > > drivers/tty/serial/sc16is7xx.c | 150 +++++++++++++-----
> > > 2 files changed, 156 insertions(+), 40 deletions(-)
> > >
> > >
> > > base-commit: 8b817fded42d8fe3a0eb47b1149d907851a3c942
> >
> > It would be a lot of sending, to do that for every patch separately, so=
 for whole series:
> > Reviewed-by: Lech Perczak <lech.perczak@camlingroup.com>
> >
> > And where applicable - for code patches:
> > Tested-by: Lech Perczak <lech.perczak@camlingroup.com>
> >
> > I tested whole series at the same time.
> > I did my tests on an i.MX6 board with SC16IS760 over SPI, which differs=
 a tiny bit from SC16IS752,
> > and everything works as it should.
> > Thank you for fixing this!
>
> Hi Lech,
> thank for your feedback.
>
> You mentioned before that without the patch "mark IOCONTROL register as v=
olatile", things were not working properly for you. Could you retest by rem=
oving this patch and see if things are still working?
>
> Thank you, Hugo.

Hello Hugo,

Just checked - this patch is required, reverting it causes things to fail, =
so this patch should be marked as a pre-requisite for the actual fix and in=
cluded in backports.
Perhaps using direct write to this register made it work, but it was likely=
 by accident.

--=20
Pozdrawiam/With kind regards,
Lech Perczak

Sr. Software Engineer
Camlin Technologies Poland Limited Sp. z o.o.
Strzegomska 54,
53-611 Wroclaw
Tel:     (+48) 71 75 000 16
Email:   lech.perczak@camlingroup.com
Website: http://www.camlingroup.com