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Message-ID: <CAMpxmJUvMTevyhkvq0YXg5d=G5qBzhi0mz0w0TjUuWCCvnnRCQ@mail.gmail.com>
Date: Fri, 25 Jun 2021 13:53:01 +0200
From: Bartosz Golaszewski <bgolaszewski@...libre.com>
To: Sergio Paracuellos <sergio.paracuellos@...il.com>
Cc: linux-gpio <linux-gpio@...r.kernel.org>,
Matthias Brugger <matthias.bgg@...il.com>,
Linus Walleij <linus.walleij@...aro.org>,
git@...nthomson.fastmail.com.au,
LKML <linux-kernel@...r.kernel.org>, neil@...wn.name,
René van Dorst <opensource@...rst.com>,
Nicholas Mc Guire <hofrat@...dl.org>
Subject: Re: [PATCH] gpio: mt7621: support gpio-line-names property
On Sat, Jun 19, 2021 at 9:35 AM Sergio Paracuellos
<sergio.paracuellos@...il.com> wrote:
>
> The default handling of the gpio-line-names property by the
> gpiolib-of implementation does not work with the multiple
> gpiochip banks per device structure used by the gpio-mt7621
> driver.
>
> This commit adds driver level support for the device tree
> property so that GPIO lines can be assigned friendly names.
>
> Signed-off-by: Sergio Paracuellos <sergio.paracuellos@...il.com>
> ---
> Hi,
>
> This driver has three gpiochips with 32 gpios each. Core implmentation
> got gpio's repeated along each gpio chip if chip.names is not assigned.
> To avoid this behaviour driver will set this names as empty or
> with desired friendly line names. Consider the following sample with
> minimal entries for the first chip with this patch changes applied:
>
> &gpio {
> gpio-line-names = "", "", "", "",
> "", "", "SFP LOS", "extcon port5 PoE compat",
> "SFP module def0", "LED blue SFP", "SFP tx disable", "",
> "switch USB power", "mode", "", "buzzer",
> "LED blue pwr", "switch port5 PoE out", "reset";
> };
>
> gpioinfo
> gpiochip0 - 32 lines:
> line 0: unnamed unused output active-high
> line 1: unnamed unused input active-high
> line 2: unnamed unused input active-high
> line 3: unnamed unused input active-high
> line 4: unnamed unused input active-high
> line 5: unnamed unused input active-high
> line 6: "SFP LOS" "los" input active-high [used]
> line 7: "extcon port5 PoE compat" unused input active-high
> line 8: "SFP module def0" "mod-def0" input active-low [used]
> line 9: "LED blue SFP" "blue:sfp" output active-high [used]
> line 10: "SFP tx disable" "tx-disable" output active-high [used]
> line 11: unnamed unused output active-high
> line 12: "switch USB power" "usb_power" output active-high [used]
> line 13: "mode" "mode" input active-high [used]
> line 14: unnamed unused input active-high
> line 15: "buzzer" "buzzer" output active-high [used]
> line 16: "LED blue pwr" "blue:pwr" output active-high [used]
> line 17: "switch port5 PoE out" "sysfs" input active-high [used]
> line 18: "reset" "reset" input active-high [used]
> line 19: unnamed unused input active-high
> line 20: unnamed unused input active-high
> line 21: unnamed unused input active-high
> line 22: unnamed unused input active-high
> line 23: unnamed unused input active-high
> line 24: unnamed unused input active-high
> line 25: unnamed unused input active-high
> line 26: unnamed unused input active-high
> line 27: unnamed unused input active-high
> line 28: unnamed unused input active-high
> line 29: unnamed unused input active-high
> line 30: unnamed unused input active-high
> line 31: unnamed unused input active-high
> gpiochip1 - 32 lines:
> line 0: unnamed unused input active-high
> line 1: unnamed unused input active-high
> ...
> line 31: unnamed unused input active-high
> gpiochip2 - 32 lines:
> line 0: unnamed unused input active-high
> line 1: unnamed unused input active-high
> ...
> line 31: unnamed unused input active-high
>
> To avoid gpiochip1 and gpiochip2 entries repeated with this
> minimal lines definition change, we assign empty reserved
> 'names' in driver code.
>
> Note that we also don't want to to prevent the driver from
> succeeding at probe due to an error in the gpio-line-names
> property and the ENODATA error is considered a valid result
> to terminate any further labeling so there is no need for
> an error message in that case. Other error results are
> unexpected so an error message indicating the consequence
> of the error is appropriate here.
>
> Thanks in advance for your time.
>
> Best regards,
> Sergio Paracuellos
>
> drivers/gpio/gpio-mt7621.c | 41 ++++++++++++++++++++++++++++++++++++++
> 1 file changed, 41 insertions(+)
>
> diff --git a/drivers/gpio/gpio-mt7621.c b/drivers/gpio/gpio-mt7621.c
> index 82fb20dca53a..b5f8fd8e928a 100644
> --- a/drivers/gpio/gpio-mt7621.c
> +++ b/drivers/gpio/gpio-mt7621.c
> @@ -206,6 +206,45 @@ mediatek_gpio_xlate(struct gpio_chip *chip,
> return gpio % MTK_BANK_WIDTH;
> }
>
> +static void
> +mediatek_gpio_set_names(struct device *dev, struct mtk_gc *rg)
> +{
> + struct device_node *np = dev->of_node;
> + const char **names;
> + int nstrings, base;
> + unsigned int i;
> +
> + names = devm_kcalloc(dev, MTK_BANK_WIDTH, sizeof(*names),
> + GFP_KERNEL);
> + if (!names)
> + return;
While the ENODATA bit makes sense, not failing after an OOM in a
driver is wrong. Please return the error code here.
Bartosz
> +
> + base = rg->bank * MTK_BANK_WIDTH;
> + nstrings = of_property_count_strings(np, "gpio-line-names");
> + if (nstrings <= base)
> + goto assign_names;
> +
> + for (i = 0; i < MTK_BANK_WIDTH; i++) {
> + const char *name;
> + int ret;
> +
> + ret = of_property_read_string_index(np, "gpio-line-names",
> + base + i, &name);
> + if (ret) {
> + if (ret != -ENODATA)
> + dev_err(dev, "unable to name line %d: %d\n",
> + base + i, ret);
> + break;
> + }
> +
> + if (*name)
> + names[i] = name;
> + }
> +
> +assign_names:
> + rg->chip.names = names;
> +}
> +
> static int
> mediatek_gpio_bank_probe(struct device *dev,
> struct device_node *node, int bank)
> @@ -241,6 +280,8 @@ mediatek_gpio_bank_probe(struct device *dev,
> if (!rg->chip.label)
> return -ENOMEM;
>
> + mediatek_gpio_set_names(dev, rg);
> +
> rg->irq_chip.name = dev_name(dev);
> rg->irq_chip.parent_device = dev;
> rg->irq_chip.irq_unmask = mediatek_gpio_irq_unmask;
> --
> 2.25.1
>
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