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Date:   Sat, 23 May 2020 13:01:40 +0200
From:   Wolfram Sang <wsa@kernel.org>
To:     Alain Volmat <alain.volmat@st.com>,
        Benjamin Tissoires <benjamin.tissoires@redhat.com>
Cc:     robh+dt@kernel.org, mark.rutland@arm.com,
        pierre-yves.mordret@st.com, mcoquelin.stm32@gmail.com,
        alexandre.torgue@st.com, linux-i2c@vger.kernel.org,
        devicetree@vger.kernel.org,
        linux-stm32@st-md-mailman.stormreply.com,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        fabrice.gasnier@st.com
Subject: Re: [PATCH 4/4] i2c: stm32f7: Add SMBus-specific protocols support
Message-ID: <20200523110140.GD3459@ninjato>
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> +static int stm32f7_i2c_reg_client(struct i2c_client *client)
> +{
> +	struct stm32f7_i2c_dev *i2c_dev = i2c_get_adapdata(client->adapter);
> +	int ret;
> +
> +	if (client->flags & I2C_CLIENT_HOST_NOTIFY) {
> +		/* Only enable on the first device registration */
> +		if (atomic_inc_return(&i2c_dev->host_notify_cnt) == 1) {
> +			ret = stm32f7_i2c_enable_smbus_host(i2c_dev);
> +			if (ret) {
> +				dev_err(i2c_dev->dev,
> +					"failed to enable SMBus host notify (%d)\n",
> +					ret);
> +				return ret;
> +			}
> +		}
> +	}
> +
> +	return 0;
> +}

So, as mentioned in the other review, I'd like to evaluate other
possibilities for the above:

- One option is to enable it globally in probe(). Then you lose the
  possibility to have a device at address 0x08.
- Enable it in probe() only if there is a generic binding "host-notify".
- Let the core scan for a device with HOST_NOTIFY when registering an
  adapter and then call back into the driver somehow?

Other ideas?


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