Re: [PATCH 2/3] soc: qcom: qcom_stats: Add QMP support for syncing ddr stats

[Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>]

On 4/29/25 5:52 AM, Maulik Shah wrote:
> Recent SoCs (SM8450 onwards) require QMP command to be sent before reading
> ddr stats. The duration field of ddr stats will get populated only if QMP
> command is sent.
> 
> Add support to send ddr stats freqsync QMP command.
> 
> Signed-off-by: Maulik Shah <maulik.shah@oss.qualcomm.com>
> ---
>  drivers/soc/qcom/qcom_stats.c | 30 +++++++++++++++++++++++++++++-
>  1 file changed, 29 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/soc/qcom/qcom_stats.c b/drivers/soc/qcom/qcom_stats.c
> index ee11fb0919742454d40442112787c087ba8f6598..15bdb8e6a542bbab34f788ac4270f7759ca83e3c 100644
> --- a/drivers/soc/qcom/qcom_stats.c
> +++ b/drivers/soc/qcom/qcom_stats.c
> @@ -13,6 +13,7 @@
>  #include <linux/platform_device.h>
>  #include <linux/seq_file.h>
>  
> +#include <linux/soc/qcom/qcom_aoss.h>
>  #include <linux/soc/qcom/smem.h>
>  #include <clocksource/arm_arch_timer.h>
>  
> @@ -37,6 +38,8 @@
>  #define DDR_STATS_TYPE(data)		FIELD_GET(GENMASK(15, 8), data)
>  #define DDR_STATS_FREQ(data)		FIELD_GET(GENMASK(31, 16), data)
>  
> +static struct qmp *qcom_stats_qmp;
> +
>  struct subsystem_data {
>  	const char *name;
>  	u32 smem_item;
> @@ -188,12 +191,28 @@ static int qcom_ddr_stats_show(struct seq_file *s, void *d)
>  	struct ddr_stats_entry data[DDR_STATS_MAX_NUM_MODES];
>  	void __iomem *reg = (void __iomem *)s->private;
>  	u32 entry_count;
> -	int i;
> +	int i, ret;
>  
>  	entry_count = readl_relaxed(reg + DDR_STATS_NUM_MODES_ADDR);
>  	if (entry_count > DDR_STATS_MAX_NUM_MODES)
>  		return 0;
>  
> +	if (qcom_stats_qmp) {
> +		/*
> +		 * Recent SoCs (SM8450 onwards) do not have duration field
> +		 * populated from boot up onwards for both DDR LPM Stats
> +		 * and DDR Frequency Stats.
> +		 *
> +		 * Send QMP message to Always on processor which will
> +		 * populate duration field into MSG RAM area.
> +		 *
> +		 * Sent everytime to read latest data.
> +		 */
> +		ret = qmp_send(qcom_stats_qmp, "{class: ddr, action: freqsync}");
> +		if (ret)
> +			seq_printf(s, "Error updating duration field %d\n", ret);

let's just return some error, instead of printing "error" successfully

> +	}
> +
>  	reg += DDR_STATS_ENTRY_START_ADDR;
>  	memcpy_fromio(data, reg, sizeof(struct ddr_stats_entry) * entry_count);
>  
> @@ -310,6 +329,15 @@ static int qcom_stats_probe(struct platform_device *pdev)
>  	qcom_create_subsystem_stat_files(root, config);
>  	qcom_create_soc_sleep_stat_files(root, reg, d, config);
>  	qcom_create_ddr_stat_files(root, reg, config);
> +	/*
> +	 * QMP is used for DDR stats syncing to MSG RAM for certain SoCs having

having what? (you could drop that word and the sentence would still make sense)

> +	 * (SM8450 onwards). The prior SoCs do not need QMP handle as the required
> +	 * stats are already present in MSG RAM, provided the DDR_STATS_MAGIC_KEY
> +	 * matches.
> +	 */

Konrad