linux-kernel - Re: [PATCH] mux: mmio: Do not use syscon helper to build regmap

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Message-ID: <20250123200412.6zuhlbz4zorazdhq@deport>
Date: Thu, 23 Jan 2025 14:04:12 -0600
From: Nishanth Menon <nm@...com>
To: Andrew Davis <afd@...com>,
        Greg Kroah-Hartman
	<gregkh@...uxfoundation.org>,
        Peter Rosin <peda@...ntia.se>
CC: Vignesh Raghavendra <vigneshr@...com>, Peter Rosin <peda@...ntia.se>,
        <linux-kernel@...r.kernel.org>, "Rob Herring (Arm)" <robh@...nel.org>,
        Lee
 Jones <lee@...nel.org>
Subject: Re: [PATCH] mux: mmio: Do not use syscon helper to build regmap

On 12:20-20250123, Andrew Davis wrote:
> The syscon helper device_node_to_regmap() is used to fetch a regmap
> registered to a device node. It also currently creates this regmap
> if the node did not already have a regmap associated with it. This
> should only be used on "syscon" nodes. This driver is not such a
> device and instead uses device_node_to_regmap() on its own node as
> a hacky way to create a regmap for itself.
> 
> This will not work going forward and so we should create our regmap
> the normal way by defining our regmap_config, fetching our memory
> resource, then using the normal regmap_init_mmio() function.
> 
> Signed-off-by: Andrew Davis <afd@...com>
> ---
Tested-by: Nishanth Menon <nm@...com>

Greg, Peter,

This is part of the fixes TI K3 platforms boot issues reported in
https://lore.kernel.org/all/b2413460-ec8b-4c77-99b8-4c32b262439a@ti.com/
on the latest linus master v6.13-5001-gd0d106a2bd21 + linux
next-20250123

Total set of patches tested with:
https://lore.kernel.org/all/20250119182121.3956546-1-vaishnav.a@ti.com/
https://lore.kernel.org/r/20250123181726.597144-1-afd@ti.com
https://lore.kernel.org/r/20250123181913.597304-1-afd@ti.com
https://lore.kernel.org/r/20250123182059.597491-1-afd@ti.com
https://lore.kernel.org/r/20250123182234.597665-1-afd@ti.com

Could we get this routed to master as fixes asap please to get a sane 6.14?

Cc Rob and Lee

>  drivers/mux/mmio.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mux/mmio.c b/drivers/mux/mmio.c
> index 30a952c34365f..278efdc480777 100644
> --- a/drivers/mux/mmio.c
> +++ b/drivers/mux/mmio.c
> @@ -33,6 +33,12 @@ static const struct of_device_id mux_mmio_dt_ids[] = {
>  };
>  MODULE_DEVICE_TABLE(of, mux_mmio_dt_ids);
>  
> +static const struct regmap_config mux_mmio_regmap_cfg = {
> +	.reg_bits = 32,
> +	.val_bits = 32,
> +	.reg_stride = 4,
> +};
> +
>  static int mux_mmio_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
> @@ -40,6 +46,7 @@ static int mux_mmio_probe(struct platform_device *pdev)
>  	struct regmap_field **fields;
>  	struct mux_chip *mux_chip;
>  	struct regmap *regmap;
> +	void __iomem *base;
>  	int num_fields;
>  	int ret;
>  	int i;
> @@ -47,7 +54,11 @@ static int mux_mmio_probe(struct platform_device *pdev)
>  	if (of_device_is_compatible(np, "mmio-mux")) {
>  		regmap = syscon_node_to_regmap(np->parent);
>  	} else {
> -		regmap = device_node_to_regmap(np);
> +		base = devm_platform_ioremap_resource(pdev, 0);
> +		if (IS_ERR(base))
> +			regmap = ERR_PTR(-ENODEV);
> +		else
> +			regmap = regmap_init_mmio(dev, base, &mux_mmio_regmap_cfg);
>  		/* Fallback to checking the parent node on "real" errors. */
>  		if (IS_ERR(regmap) && regmap != ERR_PTR(-EPROBE_DEFER)) {
>  			regmap = dev_get_regmap(dev->parent, NULL);
> -- 
> 2.39.2
> 

-- 
Regards,
Nishanth Menon
Key (0xDDB5849D1736249D) / Fingerprint: F8A2 8693 54EB 8232 17A3  1A34 DDB5 849D 1736 249D