linux-kernel - Re: [PATCH v6 4/5] mmc: sdhci-msm: Add Device tree parsing logic for DLL settings

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Message-ID: <fkb4iietzzmhvatmvjn6s6dpdibmnhj5g4xjcsrvzfwkipgwwz@wde3bcrqxrhw>
Date: Thu, 18 Dec 2025 07:32:39 -0600
From: Bjorn Andersson <andersson@...nel.org>
To: Ram Prakash Gupta <quic_rampraka@...cinc.com>
Cc: Ulf Hansson <ulf.hansson@...aro.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Konrad Dybcio <konradybcio@...nel.org>, Adrian Hunter <adrian.hunter@...el.com>, 
	linux-mmc@...r.kernel.org, devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-arm-msm@...r.kernel.org, dmitry.baryshkov@....qualcomm.com, quic_pragalla@...cinc.com, 
	quic_sayalil@...cinc.com, quic_nitirawa@...cinc.com, quic_bhaskarv@...cinc.com, 
	kernel@....qualcomm.com, Sachin Gupta <quic_sachgupt@...cinc.com>
Subject: Re: [PATCH v6 4/5] mmc: sdhci-msm: Add Device tree parsing logic for
 DLL settings

On Mon, Dec 15, 2025 at 05:30:08PM +0530, Ram Prakash Gupta wrote:
> From: Sachin Gupta <quic_sachgupt@...cinc.com>
> 
> This update introduces the capability to configure HS200
> and HS400 DLL settings via the device tree and parsing it.

No it doesn't, it merely reads a bunch of integers from DeviceTree and
does nothing with them.

Please write your commit message in imperative mood (avoid "This
update") and please include a reasoning for why this commit exists, or
as
https://docs.kernel.org/process/submitting-patches.html#describe-your-changes
says "Describe your problem.".

> 
> Signed-off-by: Sachin Gupta <quic_sachgupt@...cinc.com>
> Signed-off-by: Ram Prakash Gupta <quic_rampraka@...cinc.com>
> ---
>  drivers/mmc/host/sdhci-msm.c | 41 ++++++++++++++++++++++++++++++++++++
>  1 file changed, 41 insertions(+)
> 
> diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
> index dc79f828522b..1fcd92158bee 100644
> --- a/drivers/mmc/host/sdhci-msm.c
> +++ b/drivers/mmc/host/sdhci-msm.c
> @@ -266,6 +266,19 @@ struct sdhci_msm_variant_info {
>  	const struct sdhci_msm_offset *offset;
>  };
>  
> +/*
> + * DLL registers which needs be programmed with HSR settings.
> + * Add any new register only at the end and don't change the
> + * sequence.

/* You have to only add entries at the end, but I'm not going to tell you why... */

> + */
> +struct sdhci_msm_dll {
> +	u32 dll_config;
> +	u32 dll_config_2;
> +	u32 dll_config_3;
> +	u32 dll_usr_ctl;
> +	u32 ddr_config;
> +};
> +
>  struct sdhci_msm_host {
>  	struct platform_device *pdev;
>  	void __iomem *core_mem;	/* MSM SDCC mapped address */
> @@ -274,6 +287,7 @@ struct sdhci_msm_host {
>  	struct clk *xo_clk;	/* TCXO clk needed for FLL feature of cm_dll*/
>  	/* core, iface, cal and sleep clocks */
>  	struct clk_bulk_data bulk_clks[4];
> +	struct sdhci_msm_dll dll[2];
>  #ifdef CONFIG_MMC_CRYPTO
>  	struct qcom_ice *ice;
>  #endif
> @@ -302,6 +316,7 @@ struct sdhci_msm_host {
>  	u32 dll_config;
>  	u32 ddr_config;

So this dll_config/ddr_config pair is no longer supposed to be used? Or
are there now two sets of dll and ddr configurations to be provided?

Regards,
Bjorn

>  	bool vqmmc_enabled;
> +	bool artanis_dll;
>  };
>  
>  static const struct sdhci_msm_offset *sdhci_priv_msm_offset(struct sdhci_host *host)
> @@ -2534,6 +2549,23 @@ static int sdhci_msm_gcc_reset(struct device *dev, struct sdhci_host *host)
>  	return ret;
>  }
>  
> +#define DLL_SIZE 10
> +static int sdhci_msm_dt_parse_dll_info(struct device *dev, struct sdhci_msm_host *msm_host)
> +{
> +	u32 *dll_table = &msm_host->dll[0].dll_config;
> +	int ret;
> +
> +	msm_host->artanis_dll = false;
> +
> +	ret = of_property_read_variable_u32_array(dev->of_node,
> +						  "qcom,dll-presets",
> +						  dll_table, DLL_SIZE, DLL_SIZE);
> +	if (ret == DLL_SIZE)
> +		msm_host->artanis_dll = true;
> +
> +	return ret;
> +}
> +
>  static int sdhci_msm_probe(struct platform_device *pdev)
>  {
>  	struct sdhci_host *host;
> @@ -2580,6 +2612,15 @@ static int sdhci_msm_probe(struct platform_device *pdev)
>  
>  	msm_host->saved_tuning_phase = INVALID_TUNING_PHASE;
>  
> +	/*
> +	 * Parse HSR dll only when property is present in DT.
> +	 */
> +	ret = sdhci_msm_dt_parse_dll_info(&pdev->dev, msm_host);
> +	if (ret == -ENODATA || ret == -EOVERFLOW) {
> +		dev_err(&pdev->dev, "Bad DLL in dt (%d)\n", ret);
> +		return ret;
> +	}
> +
>  	ret = sdhci_msm_gcc_reset(&pdev->dev, host);
>  	if (ret)
>  		return ret;
> -- 
> 2.34.1
>