From: Wolfram Sang <wsa@kernel.org>
To: Heiner Kallweit <hkallweit1@gmail.com>
Cc: Rob Herring <robh+dt@kernel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
"linux-i2c@vger.kernel.org" <linux-i2c@vger.kernel.org>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>
Subject: Re: [PATCH v2 2/3] i2c: algo: bit: allow getsda to be NULL
Date: Mon, 16 May 2022 21:31:36 +0200 [thread overview]
Message-ID: <YoKmmIz7qJbD+hPY@kunai> (raw)
In-Reply-To: <2adcd797-f3cc-c8c7-c18c-d3726b2db4c0@gmail.com>
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Hi Heiner,
> /* read ack: SDA should be pulled down by slave, or it may
> * NAK (usually to report problems with the data we wrote).
> + * Report ACK if SDA is write-only.
Minor nit: On first read, I didn't understand. "Always report ACK..." is
maybe a tad clearer.
> */
> @@ -203,6 +204,9 @@ static int i2c_inb(struct i2c_adapter *i2c_adap)
> unsigned char indata = 0;
> struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
>
> + if (!adap->getsda)
> + return -EOPNOTSUPP;
Wouldn't it be better in 'readbytes' returning an errno there?
> - /* Complain if SCL can't be read */
> - if (bit_adap->getscl == NULL) {
> + if (bit_adap->getscl == NULL && bit_adap->getsda == NULL)
> + dev_info(&adap->dev, "I2C-like interface, SDA and SCL are write-only\n");
> + else if (bit_adap->getscl == NULL) {
> + /* Complain if SCL can't be read */
> dev_warn(&adap->dev, "Not I2C compliant: can't read SCL\n");
> dev_warn(&adap->dev, "Bus may be unreliable\n");
Hmm, this is a bit inconsistent with dev_warn and dev_info. How about
this?
if (bit_adap->getscl == NULL)
dev_warn(&adap->dev, "Not I2C compliant: can't read SCL\n");
if (bit_adap->getsda == NULL)
dev_warn(&adap->dev, "Not I2C compliant: can't read SDA\n");
if (bit_adap->getscl == NULL || bit_adap->getsda == NULL)
dev_warn(&adap->dev, "Bus may be unreliable\n");
The above code can surely be simplified. I just wanted to show this
simple approach so we can discuss my suggestion.
All the best,
Wolfram
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next prev parent reply other threads:[~2022-05-16 19:31 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-27 19:20 [PATCH v2 0/3] i2c: gpio: support write-only sda Heiner Kallweit
2022-04-27 19:23 ` [PATCH v2 1/3] dt-bindings: i2c-gpio: Add property i2c-gpio,sda-output-only Heiner Kallweit
2022-05-03 21:11 ` Rob Herring
2022-04-27 19:24 ` [PATCH v2 2/3] i2c: algo: bit: allow getsda to be NULL Heiner Kallweit
2022-05-16 19:31 ` Wolfram Sang [this message]
2022-08-14 21:06 ` Heiner Kallweit
2022-04-27 19:25 ` [PATCH v2 3/3] i2c: gpio: support write-only sda Heiner Kallweit
2022-05-16 19:37 ` Wolfram Sang
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