linux-kernel - Re: [PATCH v2] nvmem: mtk-efuse: Only register socinfo device if needed cells are there

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Message-ID: <a1914f2b-93f2-4de4-9c4b-2e1f6b39cf3a@collabora.com>
Date: Wed, 10 Jul 2024 11:31:11 +0200
From: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
To: Nícolas F. R. A. Prado <nfraprado@...labora.com>,
 Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
 Matthias Brugger <matthias.bgg@...il.com>, Chen-Yu Tsai <wenst@...omium.org>
Cc: kernel@...labora.com, linux-kernel@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH v2] nvmem: mtk-efuse: Only register socinfo device if
 needed cells are there

Il 08/07/24 21:43, Nícolas F. R. A. Prado ha scritto:
> Not every efuse region has cells storing SoC information. Only register
> an socinfo device if the required cells are present.
> 
> This prevents the pointless process of creating an socinfo device,
> probing it with the socinfo driver only to ultimately error out like so
> 
>    mtk-socinfo mtk-socinfo.0.auto: error -ENOENT: Failed to get socinfo data
>    mtk-socinfo mtk-socinfo.0.auto: probe with driver mtk-socinfo failed with error -2
> 
> This issue is observed on the mt8183-kukui-jacuzzi-juniper-sku16
> platform, which has two efuse regions, but only one of them contains the
> SoC data.
> 

I think that we should rather remove or disable the first eFuse region, as
even though that is enabled:

  - This is the only SoC having two regions
    - I'm not even sure that the region at 0x8000000 is really efuse
    - Not even referenced in datasheets....
  - It's unused, as in, it's not exposing any information and no declared cells

Don't misunderstand me, this is not an invalid change, but I rather prefer
to resolve this by disabling that (effectively unused!) node, avoiding to
add more lines to this driver that would be useless after fixing that small
single thing.

Cheers,
Angelo


> Signed-off-by: Nícolas F. R. A. Prado <nfraprado@...labora.com>
> ---
> Changes in v2:
> - Added missing include for of.h
> - Link to v1: https://lore.kernel.org/r/20240708-mtk-socinfo-no-data-probe-err-v1-1-fb2acd3a47bf@collabora.com
> ---
>   drivers/nvmem/mtk-efuse.c | 18 ++++++++++++++----
>   1 file changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/nvmem/mtk-efuse.c b/drivers/nvmem/mtk-efuse.c
> index 9caf04667341..74def409bc20 100644
> --- a/drivers/nvmem/mtk-efuse.c
> +++ b/drivers/nvmem/mtk-efuse.c
> @@ -11,6 +11,7 @@
>   #include <linux/nvmem-provider.h>
>   #include <linux/platform_device.h>
>   #include <linux/property.h>
> +#include <linux/of.h>
>   
>   struct mtk_efuse_pdata {
>   	bool uses_post_processing;
> @@ -60,6 +61,8 @@ static void mtk_efuse_fixup_dt_cell_info(struct nvmem_device *nvmem,
>   		cell->read_post_process = mtk_efuse_gpu_speedbin_pp;
>   }
>   
> +static const char socinfo_data_first_name[] = "socinfo-data1";
> +
>   static int mtk_efuse_probe(struct platform_device *pdev)
>   {
>   	struct device *dev = &pdev->dev;
> @@ -69,6 +72,7 @@ static int mtk_efuse_probe(struct platform_device *pdev)
>   	struct mtk_efuse_priv *priv;
>   	const struct mtk_efuse_pdata *pdata;
>   	struct platform_device *socinfo;
> +	struct device_node *np;
>   
>   	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
>   	if (!priv)
> @@ -92,10 +96,16 @@ static int mtk_efuse_probe(struct platform_device *pdev)
>   	if (IS_ERR(nvmem))
>   		return PTR_ERR(nvmem);
>   
> -	socinfo = platform_device_register_data(&pdev->dev, "mtk-socinfo",
> -						PLATFORM_DEVID_AUTO, NULL, 0);
> -	if (IS_ERR(socinfo))
> -		dev_info(dev, "MediaTek SoC Information will be unavailable\n");
> +	np = of_get_child_by_name(pdev->dev.of_node, socinfo_data_first_name);
> +	if (np) {
> +		of_node_put(np);
> +		socinfo = platform_device_register_data(&pdev->dev, "mtk-socinfo",
> +							PLATFORM_DEVID_AUTO, NULL, 0);
> +		if (IS_ERR(socinfo))
> +			dev_info(dev, "MediaTek SoC Information will be unavailable\n");
> +	} else {
> +		dev_info(dev, "Efuse region does not contain SoC information - skipping socinfo driver setup\n");
> +	}
>   
>   	platform_set_drvdata(pdev, socinfo);
>   	return 0;
> 
> ---
> base-commit: 0b58e108042b0ed28a71cd7edf5175999955b233
> change-id: 20240708-mtk-socinfo-no-data-probe-err-d7558343dc82
> 
> Best regards,