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Date:   Wed, 15 Apr 2020 10:16:54 +0200
From:   Wolfram Sang <wsa@the-dreams.de>
To:     Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Cc:     Luca Ceresoli <luca@lucaceresoli.net>,
        Wolfram Sang <wsa+renesas@sang-engineering.com>,
        linux-i2c@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
        linux-i3c@lists.infradead.org,
        Niklas =?utf-8?Q?S=C3=B6derlund?= <niklas.soderlund@ragnatech.se>,
        Jacopo Mondi <jacopo@jmondi.org>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Vladimir Zapolskiy <vz@mleia.com>,
        linux-kernel@vger.kernel.org,
        Geert Uytterhoeven <geert+renesas@glider.be>,
        Rob Herring <robh@kernel.org>
Subject: Re: [RFC PATCH v2 2/6] i2c: allow DT nodes without 'compatible'
Message-ID: <20200415081654.GC1141@ninjato>
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> Aha, is it easy enough to distinguish that difference in user-space so
> that we can present a specific character to indicate this in i2cdetect?
> Or is that not so easy?

I thought about it shortly but have not come up with a way of doing
that. This is the code in i2cdetect:

	/* Set slave address */
	if (ioctl(file, I2C_SLAVE, i+j) < 0) {
		if (errno == EBUSY) {
			printf("UU ");
			continue;
		} else {
			fprintf(stderr, "Error: Could not set "
				"address to 0x%02x: %s\n", i+j,
				strerror(errno));
			return -1;
		}
	}

So, if we chose to use another errno to indicate 'reserved' and update
i2cdetect, all old versions of i2cdetect will have ugly error messages.
And adding another IOCTL just for printing reserved addresses neither
sounds great.


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