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From: Linus Walleij <linus.walleij@linaro.org>
To: Bartosz Golaszewski <brgl@bgdev.pl>
Cc: Mark Brown <broonie@kernel.org>,
	Florian Fainelli <florian.fainelli@broadcom.com>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Ray Jui <rjui@broadcom.com>,
	Scott Branden <sbranden@broadcom.com>,
	Broadcom internal kernel review list 
	<bcm-kernel-feedback-list@broadcom.com>,
	linux-spi@vger.kernel.org, linux-rpi-kernel@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-gpio@vger.kernel.org,
	Bartosz Golaszewski <bartosz.golaszewski@linaro.org>,
	Dan Carpenter <dan.carpenter@linaro.org>
Subject: Re: [RFT PATCH v2] spi: bcm2835: reduce the abuse of the GPIO API
Date: Fri, 1 Sep 2023 14:15:39 +0200	[thread overview]
Message-ID: <CACRpkdYLcOZQ9r46aBwesh-H392C_0AWC8n2ikuwUknfEhoNNA@mail.gmail.com> (raw)
In-Reply-To: <20230901111548.12733-1-brgl@bgdev.pl>

On Fri, Sep 1, 2023 at 1:15 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:

> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
>
> Currently the bcm2835 SPI driver uses functions that are available
> exclusively to GPIO providers as a way to handle a platform quirk. Let's
> use a slightly better alternative that avoids poking around in GPIOLIB's
> internals and use GPIO lookup tables.
>
> Link: https://www.spinics.net/lists/linux-gpio/msg36218.html
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

> +#include <linux/cleanup.h>
(...)
> -       struct gpio_chip *chip;
> +       struct gpiod_lookup_table *lookup __free(kfree) = NULL;

Whoa!
This is really neat.
As noted, it will confuse static checkers at no end, but they just have
to adopt. (CC to Dan C if he now runs into this.)

> +       gpiod_add_lookup_table(lookup);

Maybe we should mention the obvious advantage to the previous
hack: if there is a "cs-gpios" in the device tree, it will take precedence,
because gpiod_find_and_request() will try gpiod_find_by_fwnode()
*first* and only if this fails it will fall back to gpiod_find().

Hm, maybe we should go and fix these device trees? :P

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

Yours,
Linus Walleij

  reply	other threads:[~2023-09-01 12:15 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-01 11:15 [RFT PATCH v2] spi: bcm2835: reduce the abuse of the GPIO API Bartosz Golaszewski
2023-09-01 12:15 ` Linus Walleij [this message]
2023-09-01 12:30   ` Mark Brown
2023-09-01 12:33     ` Bartosz Golaszewski
2023-09-01 12:57       ` Mark Brown
2023-09-02 16:56     ` Linus Walleij
2023-09-04  8:55       ` Andy Shevchenko
2023-09-05  8:27   ` Dan Carpenter

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