Re: Patch "MIPS: pci: lantiq: restore reset gpio polarity" has been added to the 6.9-stable tree

[Martin Schiller <ms@dev.tdt.de>]

On 2024-06-24 19:01, gregkh@linuxfoundation.org wrote:
> This is a note to let you know that I've just added the patch titled
> 
>     MIPS: pci: lantiq: restore reset gpio polarity
> 
> to the 6.9-stable tree which can be found at:
> 
> http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
> 
> The filename of the patch is:
>      mips-pci-lantiq-restore-reset-gpio-polarity.patch
> and it can be found in the queue-6.9 subdirectory.
> 
> If you, or anyone else, feels it should not be added to the stable 
> tree,
> please let <stable@vger.kernel.org> know about it.


This patch is buggy and should not go into the stable trees.
It has already been reverted upstream in the mips-fixes.

Thank you very much and sorry for the inconvenience,
Martin

> 
> 
> From 277a0363120276645ae598d8d5fea7265e076ae9 Mon Sep 17 00:00:00 2001
> From: Martin Schiller <ms@dev.tdt.de>
> Date: Fri, 7 Jun 2024 11:04:00 +0200
> Subject: MIPS: pci: lantiq: restore reset gpio polarity
> 
> From: Martin Schiller <ms@dev.tdt.de>
> 
> commit 277a0363120276645ae598d8d5fea7265e076ae9 upstream.
> 
> Commit 90c2d2eb7ab5 ("MIPS: pci: lantiq: switch to using gpiod API") 
> not
> only switched to the gpiod API, but also inverted / changed the 
> polarity
> of the GPIO.
> 
> According to the PCI specification, the RST# pin is an active-low
> signal. However, most of the device trees that have been widely used 
> for
> a long time (mainly in the openWrt project) define this GPIO as
> active-high and the old driver code inverted the signal internally.
> 
> Apparently there are actually boards where the reset gpio must be
> operated inverted. For this reason, we cannot use the 
> GPIOD_OUT_LOW/HIGH
> flag for initialization. Instead, we must explicitly set the gpio to
> value 1 in order to take into account any "GPIO_ACTIVE_LOW" flag that
> may have been set.
> 
> In order to remain compatible with all these existing device trees, we
> should therefore keep the logic as it was before the commit.
> 
> Fixes: 90c2d2eb7ab5 ("MIPS: pci: lantiq: switch to using gpiod API")
> Cc: stable@vger.kernel.org
> Signed-off-by: Martin Schiller <ms@dev.tdt.de>
> Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
>  arch/mips/pci/pci-lantiq.c |    8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> --- a/arch/mips/pci/pci-lantiq.c
> +++ b/arch/mips/pci/pci-lantiq.c
> @@ -124,14 +124,14 @@ static int ltq_pci_startup(struct platfo
>  		clk_disable(clk_external);
> 
>  	/* setup reset gpio used by pci */
> -	reset_gpio = devm_gpiod_get_optional(&pdev->dev, "reset",
> -					     GPIOD_OUT_LOW);
> +	reset_gpio = devm_gpiod_get_optional(&pdev->dev, "reset", 
> GPIOD_ASIS);
>  	error = PTR_ERR_OR_ZERO(reset_gpio);
>  	if (error) {
>  		dev_err(&pdev->dev, "failed to request gpio: %d\n", error);
>  		return error;
>  	}
>  	gpiod_set_consumer_name(reset_gpio, "pci_reset");
> +	gpiod_direction_output(reset_gpio, 1);
> 
>  	/* enable auto-switching between PCI and EBU */
>  	ltq_pci_w32(0xa, PCI_CR_CLK_CTRL);
> @@ -194,10 +194,10 @@ static int ltq_pci_startup(struct platfo
> 
>  	/* toggle reset pin */
>  	if (reset_gpio) {
> -		gpiod_set_value_cansleep(reset_gpio, 1);
> +		gpiod_set_value_cansleep(reset_gpio, 0);
>  		wmb();
>  		mdelay(1);
> -		gpiod_set_value_cansleep(reset_gpio, 0);
> +		gpiod_set_value_cansleep(reset_gpio, 1);
>  	}
>  	return 0;
>  }
> 
> 
> Patches currently in stable-queue which might be from ms@dev.tdt.de are
> 
> queue-6.9/mips-pci-lantiq-restore-reset-gpio-polarity.patch