linux-kernel - Re: [PATCH 1/3] spi: spidev: fix the check for spidev in dt

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Message-ID: <20160626011315.GE28202@sirena.org.uk>
Date:	Sun, 26 Jun 2016 02:13:15 +0100
From:	Mark Brown <broonie@...nel.org>
To:	Michal Suchanek <hramrach@...il.com>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Ingo Molnar <mingo@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Kees Cook <keescook@...omium.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Dan Williams <dan.j.williams@...el.com>,
	Tejun Heo <tj@...nel.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Davidlohr Bueso <dave@...olabs.net>,
	Andrey Ryabinin <aryabinin@...tuozzo.com>,
	Nikolay Aleksandrov <nikolay@...ulusnetworks.com>,
	Dmitry Vyukov <dvyukov@...gle.com>,
	Adrien Schildknecht <adrien+dev@...ischi.me>,
	linux-kernel@...r.kernel.org, linux-spi@...r.kernel.org
Subject: Re: [PATCH 1/3] spi: spidev: fix the check for spidev in dt

On Thu, Jun 23, 2016 at 05:41:19PM -0000, Michal Suchanek wrote:

> The check is supposed to warn about spidev specified directly in
> devicetree as compatible. This just does not work. I have a devicetree
> with no compatible whatsoever and hacked my kernel so I can manually
> bind spidev. This still triggers.

Well, a DT device won't instantiate without a compatible string...
could you please explain exactly what makes you say this won't work?

> Also I have no idea how this could have build with ! CONFIG_OF since the
> id table which the code checks is not compiled then.

of_match_device() compiles out when !OF.

> +static const struct of_device_id spidev_check[] = {
> +			{ .compatible = "spidev" },
> +			{}
> +};

The indentation here is completely non-standard.

> -	if (spi->dev.of_node && !of_match_device(spidev_dt_ids, &spi->dev)) {
> +	if (spi->dev.of_node && of_match_device(spidev_check, &spi->dev)) {

I think what you intend to say in the commit message is that you want to
change from a whitelist to a blacklist since that is what the code says,
but like I say we also need an explanation of the logic behind such a
change.

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