Re: [PATCH v3 2/2] memory: mtk-smi: mt8188: Add SMI reset and clamp for MT8188

[Philipp Zabel <p.zabel@pengutronix.de>]

On Di, 2025-01-21 at 14:49 +0800, Friday Yang wrote:
> From: "friday.yang" <friday.yang@mediatek.com>
> 
> To prevent handling glitch signals during MTCMOS on/off transitions,
> SMI requires clamp and reset operations. Parse the reset settings for
> SMI LARBs and the clamp settings for the SMI Sub-Common. Register
> genpd callback for the SMI LARBs located in image, camera and IPE
> subsystems, and apply reset and clamp operations within the callback.
> 
> Signed-off-by: Friday Yang <friday.yang@mediatek.com>
> ---
>  drivers/memory/mtk-smi.c | 141 +++++++++++++++++++++++++++++++++++++--
>  1 file changed, 137 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/memory/mtk-smi.c b/drivers/memory/mtk-smi.c
> index 5710348f72f6..aaeb80379ec1 100644
> --- a/drivers/memory/mtk-smi.c
> +++ b/drivers/memory/mtk-smi.c
[...]
> @@ -528,6 +598,53 @@ static int mtk_smi_dts_clk_init(struct device *dev, struct mtk_smi *smi,
>  	return ret;
>  }
> 
> +static int mtk_smi_larb_parse_clamp_optional(struct mtk_smi_larb *larb)
> +{
> +	struct device *dev = larb->dev;
> +	const struct mtk_smi_larb_gen *larb_gen = larb->larb_gen;
> +	u32 larb_id;
> +	int ret;
> +
> +	/**
> +	 * Only SMI LARBs in camera, image and IPE subsys need to
> +	 * apply clamp and reset operations, others can be skipped.
> +	 */
> +	ret = of_property_read_u32(dev->of_node, "mediatek,larb-id", &larb_id);
> +	if (ret)
> +		return -EINVAL;
> +	if (!larb_gen->clamp_port || !larb_gen->clamp_port[larb_id])
> +		return 0;
> +
> +	larb->sub_comm_inport = larb_gen->clamp_port[larb_id];
> +	larb->sub_comm_syscon = syscon_regmap_lookup_by_phandle(dev->of_node, "mediatek,smi");
> +	if (IS_ERR(larb->sub_comm_syscon)) {
> +		larb->sub_comm_syscon = NULL;
> +		return dev_err_probe(dev, -EINVAL,
> +				     "Unknown clamp port for larb %d\n", larb_id);
> +	}
> +
> +	return 0;
> +}
> +
> +static int mtk_smi_larb_parse_reset_optional(struct mtk_smi_larb *larb)
> +{
> +	struct device *dev = larb->dev;
> +	int ret;
> +
> +	larb->rst_con = devm_reset_control_get(dev, "larb");

Please use devm_reset_control_get_exclusive() directly.
Or use devm_reset_control_get_optional_exclusive(), which returns NULL
instead of -ENOENT. That way you can ...

> +	if (IS_ERR(larb->rst_con))
> +		return dev_err_probe(dev, PTR_ERR(larb->rst_con),
> +				     "Failed to get larb reset controller\n");

... suppress this error message in case of -ENOENT and return with:

	if (!larb->rst_con)
		return 0;

here.

> +
> +	larb->nb.notifier_call = mtk_smi_genpd_callback;
> +	ret = dev_pm_genpd_add_notifier(dev, &larb->nb);
> +	if (ret)
> +		return dev_err_probe(dev, -EINVAL,
> +				     "Failed to add genpd callback %d\n", ret);
> +
> +	return 0;
> +}
> +
>  static int mtk_smi_larb_probe(struct platform_device *pdev)
>  {
>  	struct mtk_smi_larb *larb;
> @@ -538,6 +655,7 @@ static int mtk_smi_larb_probe(struct platform_device *pdev)
>  	if (!larb)
>  		return -ENOMEM;
> 
> +	larb->dev = dev;
>  	larb->larb_gen = of_device_get_match_data(dev);
>  	larb->base = devm_platform_ioremap_resource(pdev, 0);
>  	if (IS_ERR(larb->base))
> @@ -554,15 +672,24 @@ static int mtk_smi_larb_probe(struct platform_device *pdev)
>  	if (ret < 0)
>  		return ret;
> 
> -	pm_runtime_enable(dev);
> +	ret = mtk_smi_larb_parse_clamp_optional(larb);
> +	if (ret)
> +		goto err_link_remove;
> +
> +	ret = mtk_smi_larb_parse_reset_optional(larb);
> +	if (ret && ret != -ENOENT)

The ret != -ENOENT check could be dropped if you use
devm_reset_control_get_optional_exclusive() above.


regards
Philipp