From: Jonathan Cameron <jic23@kernel.org>
To: Eddie James <eajames@linux.ibm.com>
Cc: Jonathan Cameron <Jonathan.Cameron@Huawei.com>,
linux-iio@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org, krzysztof.kozlowski+dt@linaro.org,
robh+dt@kernel.org, lars@metafoo.de, miltonm@us.ibm.com
Subject: Re: [PATCH v2 0/2] iio: humidity: si7020: Check device property for skipping reset in probe
Date: Sat, 14 May 2022 14:40:30 +0100 [thread overview]
Message-ID: <20220514144030.7a57da70@jic23-huawei> (raw)
In-Reply-To: <c2f7b09d-e046-409e-b65e-153157f84b03@linux.ibm.com>
On Thu, 12 May 2022 14:11:06 -0500
Eddie James <eajames@linux.ibm.com> wrote:
> On 5/12/22 11:48, Jonathan Cameron wrote:
> > On Thu, 12 May 2022 11:20:18 -0500
> > Eddie James <eajames@linux.ibm.com> wrote:
> >
> >> I2C commands issued after the SI7020 is starting up or after reset
> >> can potentially upset the startup sequence. Therefore, the host
> >> needs to wait for the startup sequence to finish before issuing
> >> further i2c commands. This is impractical in cases where the SI7020
> >> is on a shared bus or behind a mux, which may switch channels at
> >> any time (generating I2C traffic). Therefore, check for a device
> >> property that indicates that the driver should skip resetting the
> >> device when probing.
> > Why not lock the bus? It's not ideal, but then not resetting and hence
> > potentially ending up in an unknown state isn't great either.
>
>
> Also, I should mention that in our case we can rely on the power on
> reset, so the device should be in a known state.
Until someone unbinds and rebinds the driver...
It's very hard to have any guarantees once users are involved :)
Jonathan
>
> Eddie
>
>
> >
> > Jonathan
> >
> >> Changes since v1:
> >> - Fix dt binding document
> >>
> >> Eddie James (2):
> >> dt-bindings: iio: humidity: Add si7020 bindings
> >> iio: humidity: si7020: Check device property for skipping reset in probe
> >>
> >> .../bindings/iio/humidity/silabs,si7020.yaml | 47 +++++++++++++++++++
> >> .../devicetree/bindings/trivial-devices.yaml | 2 -
> >> drivers/iio/humidity/si7020.c | 14 +++---
> >> 3 files changed, 55 insertions(+), 8 deletions(-)
> >> create mode 100644 Documentation/devicetree/bindings/iio/humidity/silabs,si7020.yaml
> >>
prev parent reply other threads:[~2022-05-14 13:32 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-12 16:20 [PATCH v2 0/2] iio: humidity: si7020: Check device property for skipping reset in probe Eddie James
2022-05-12 16:20 ` [PATCH v2 1/2] dt-bindings: iio: humidity: Add si7020 bindings Eddie James
2022-05-12 16:51 ` Jonathan Cameron
2022-05-12 17:08 ` Eddie James
2022-05-13 16:47 ` Jonathan Cameron
2022-05-13 8:55 ` Krzysztof Kozlowski
2022-05-12 16:20 ` [PATCH v2 2/2] iio: humidity: si7020: Check device property for skipping reset in probe Eddie James
2022-05-12 16:48 ` [PATCH v2 0/2] " Jonathan Cameron
2022-05-12 17:08 ` Eddie James
2022-05-13 16:45 ` Jonathan Cameron
2022-05-13 22:48 ` Peter Rosin
2022-05-14 13:43 ` Jonathan Cameron
2022-05-14 15:02 ` Peter Rosin
2022-05-18 15:28 ` Eddie James
2022-05-18 15:51 ` Eddie James
2022-05-12 19:11 ` Eddie James
2022-05-14 13:40 ` Jonathan Cameron [this message]
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