linux-kernel - Re: [PATCH v3 1/3] Input: ads7846

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Date:   Mon, 8 May 2023 18:16:00 +0300
From:   andy.shevchenko@...il.com
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     Aaro Koskinen <aaro.koskinen@....fi>,
        Janusz Krzysztofik <jmkrzyszt@...il.com>,
        Tony Lindgren <tony@...mide.com>,
        Russell King <linux@...linux.org.uk>,
        Daniel Mack <daniel@...que.org>,
        Haojian Zhuang <haojian.zhuang@...il.com>,
        Robert Jarzmik <robert.jarzmik@...e.fr>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Bartosz Golaszewski <bartosz.golaszewski@...aro.org>,
        Andreas Kemnade <andreas@...nade.info>,
        Helge Deller <deller@....de>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        linux-omap@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-mips@...r.kernel.org,
        linux-input@...r.kernel.org, linux-spi@...r.kernel.org,
        linux-fbdev@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-mmc@...r.kernel.org
Subject: Re: [PATCH v3 1/3] Input: ads7846 - Convert to use software nodes

Fri, May 05, 2023 at 01:16:55PM +0200, Linus Walleij kirjoitti:
> The Nokia 770 is using GPIOs from the global numberspace on the
> CBUS node to pass down to the LCD controller. This regresses when we
> let the OMAP GPIO driver use dynamic GPIO base.
> 
> The Nokia 770 now has dynamic allocation of IRQ numbers, so this
> needs to be fixed for it to work.
> 
> As this is the only user of LCD MIPID we can easily augment the
> driver to use a GPIO descriptor instead and resolve the issue.
> 
> The platform data .shutdown() callback wasn't even used in the
> code, but we encode a shutdown asserting RESET in the remove()
> callback for completeness sake.
> 
> The CBUS also has the ADS7846 touchscreen attached.
> 
> Populate the devices on the Nokia 770 CBUS I2C using software
> nodes instead of platform data quirks. This includes the LCD
> and the ADS7846 touchscreen so the conversion just brings the LCD
> along with it as software nodes is an all-or-nothing design
> pattern.
> 
> The ADS7846 has some limited support for using GPIO descriptors,
> let's convert it over completely to using device properties and then
> fix all remaining boardfile users to provide all platform data using
> software nodes.
> 
> Dump the of includes and of_match_ptr() in the ADS7846 driver as part
> of the job.
> 
> Since we have to move ADS7846 over to obtaining the GPIOs it is
> using exclusively from descriptors, we provide descriptor tables
> for the two remaining in-kernel boardfiles using ADS7846:
> 
> - PXA Spitz
> - MIPS Alchemy DB1000 development board
> 
> It was too hard for me to include software node conversion of
> these two remaining users at this time: the spitz is using a
> hscync callback in the platform data that would require further
> GPIO descriptor conversion of the Spitz, and moving the hsync
> callback down into the driver: it will just become too big of
> a job, but it can be done separately.
> 
> The MIPS Alchemy DB1000 is simply something I cannot test, so take
> the easier approach of just providing some GPIO descriptors in
> this case as I don't want the patch to grow too intrusive.

...

>  #include <linux/gpio.h>

Do we need it after this patch?

>  #include <linux/gpio/machine.h>
> +#include <linux/gpio/property.h>

...

> +static const struct software_node *nokia770_gpiochip_nodes[] = {
> +	&nokia770_mpuio_gpiochip_node,
> +	&nokia770_gpiochip1_node,
> +	&nokia770_gpiochip2_node,
> +	NULL,

Comma is redundant for the terminator entry.

> +};

...

> +static struct gpiod_lookup_table spitz_ads7846_gpio_table = {
> +	.dev_id = "spi2.0",
> +	.table = {
> +		GPIO_LOOKUP("gpio-pxa", SPITZ_GPIO_TP_INT,
> +			    "pendown", GPIO_ACTIVE_HIGH),
> +		{ },

Ditto.

> +	},
> +};

...

> +static struct gpiod_lookup_table db1100_touch_gpio_table = {
> +	.dev_id = "spi0.0",
> +	.table = {
> +		GPIO_LOOKUP("alchemy-gpio2", 21,
> +			    "pendown", GPIO_ACTIVE_HIGH),
> +		{ },

Ditto.

> +	},
> +};

-- 
With Best Regards,
Andy Shevchenko