linux-kernel - Re: [PATCH v4 3/4] mmc: sdhci-msm: Add Device tree parsing logic for DLL settings

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Message-ID: <5fc715ac-1e24-ee59-db24-cc0a5797c43e@quicinc.com>
Date: Tue, 7 Oct 2025 16:38:50 +0530
From: Ram Prakash Gupta <quic_rampraka@...cinc.com>
To: Rob Herring <robh@...nel.org>
CC: Ulf Hansson <ulf.hansson@...aro.org>,
        Krzysztof Kozlowski
	<krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Adrian Hunter
	<adrian.hunter@...el.com>,
        Bjorn Andersson <andersson@...nel.org>,
        "Konrad
 Dybcio" <konradybcio@...nel.org>, <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 v4 3/4] mmc: sdhci-msm: Add Device tree parsing logic for
 DLL settings

On 10/7/2025 3:14 AM, Rob Herring wrote:
> On Mon, Sep 29, 2025 at 05:05:14PM +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.
>>
>> 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 | 91 ++++++++++++++++++++++++++++++++++++
>>  1 file changed, 91 insertions(+)
>>
>> diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
>> index 36700735aa3e..d07f0105b733 100644
>> --- a/drivers/mmc/host/sdhci-msm.c
>> +++ b/drivers/mmc/host/sdhci-msm.c
>> @@ -265,6 +265,19 @@ 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.
>> + */
>> +struct sdhci_msm_dll {
>> +	u32 dll_config[2];
>> +	u32 dll_config_2[2];
>> +	u32 dll_config_3[2];
>> +	u32 dll_usr_ctl[2];
>> +	u32 ddr_config[2];
>> +};
>> +
>>  struct sdhci_msm_host {
>>  	struct platform_device *pdev;
>>  	void __iomem *core_mem;	/* MSM SDCC mapped address */
>> @@ -273,6 +286,7 @@ 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;
>>  #ifdef CONFIG_MMC_CRYPTO
>>  	struct qcom_ice *ice;
>>  #endif
>> @@ -301,6 +315,7 @@ struct sdhci_msm_host {
>>  	u32 dll_config;
>>  	u32 ddr_config;
>>  	bool vqmmc_enabled;
>> +	bool artanis_dll;
>>  };
>>  
>>  static const struct sdhci_msm_offset *sdhci_priv_msm_offset(struct sdhci_host *host)
>> @@ -2516,6 +2531,73 @@ static int sdhci_msm_gcc_reset(struct device *dev, struct sdhci_host *host)
>>  	return ret;
>>  }
>>  
>> +static int sdhci_msm_dt_get_array(struct device *dev, const char *prop_name,
>> +				  u32 **dll_table, int *len)
>> +{
>> +	struct device_node *np = dev->of_node;
>> +	u32 *arr = NULL;
>> +	int ret = 0, sz = 0;
>> +
>> +	if (!np)
>> +		return -ENODEV;
>> +	if (!of_get_property(np, prop_name, &sz))
> Don't add new users of of_get_property which adds untracked pointers to 
> raw DT data.

Adrian also checked and provided some suggestion, and with those I could
get rid of this function, so it is no longer needed.

>
>> +		return -EINVAL;
>> +
>> +	sz = sz / sizeof(*arr);
>> +	if (sz <= 0)
>> +		return -EINVAL;
>> +
>> +	arr = kcalloc(sz,  sizeof(*arr), GFP_KERNEL);
> Why do you need to count the length first when only 5 entries is valid?

This line also would not be needed in needed in next patchset.

>> +	if (!arr)
>> +		return -ENOMEM;
>> +
>> +	ret = of_property_read_u32_array(np, prop_name, arr, sz);
>> +	if (ret) {
>> +		dev_err(dev, "%s failed reading array %d\n", prop_name, ret);
>> +		*len = 0;
>> +		return ret;
>> +	}
>> +
>> +	*dll_table = arr;
>> +	*len = sz;
>> +
>> +	return ret;
>> +}
>> +
>> +static int sdhci_msm_dt_parse_dll_info(struct device *dev, struct sdhci_msm_host *msm_host)
>> +{
>> +	int dll_table_len, dll_reg_count;
>> +	u32 *dll_table = NULL;
>> +	int i, j;
>> +
>> +	msm_host->artanis_dll = false;
>> +
>> +	if (sdhci_msm_dt_get_array(dev, "qcom,dll-hsr-list",
>> +				   &dll_table, &dll_table_len))
>> +		return -EINVAL;
>> +
>> +	dll_reg_count = sizeof(struct sdhci_msm_dll) / sizeof(u32);
>> +
>> +	if (dll_table_len != dll_reg_count) {
>> +		dev_err(dev, "Number of HSR entries are not matching\n");
>> +		return -EINVAL;
> You just leaked memory. devm_* functions are your friend.

These changes would also be removed in next patchset, after addressing
Adrian comment.

>
>> +	}
>> +
>> +	for (i = 0, j = 0; j < 2; i = i + 5, j++) {
>> +		msm_host->dll.dll_config[j] = dll_table[i];
>> +		msm_host->dll.dll_config_2[j] = dll_table[i + 1];
>> +		msm_host->dll.dll_config_3[j] = dll_table[i + 2];
>> +		msm_host->dll.dll_usr_ctl[j] = dll_table[i + 3];
>> +		msm_host->dll.ddr_config[j] = dll_table[i + 4];
>> +	}
>> +
>> +	msm_host->artanis_dll = true;
>> +
>> +	kfree(dll_table);
>> +
>> +	return 0;
>> +}