linux-kernel - Re: [PATCH v2] platform/x86/intel/pmc: core: Add support to show LTR-ignored components

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Date:   Mon, 30 Jan 2023 14:07:11 +0100
From:   Hans de Goede <hdegoede@...hat.com>
To:     Rajat Khandelwal <rajat.khandelwal@...el.com>,
        irenic.rajneesh@...il.com, david.e.box@...el.com,
        markgross@...nel.org
Cc:     platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org,
        Rajat Khandelwal <rajat.khandelwal@...ux.intel.com>
Subject: Re: [PATCH v2] platform/x86/intel/pmc: core: Add support to show
 LTR-ignored components

Hi,

On 1/25/23 13:43, Rajat Khandelwal wrote:
> From: Rajat Khandelwal <rajat.khandelwal@...ux.intel.com>
> 
> Currently, 'ltr_ignore' sysfs attribute, when read, returns nothing, even
> if there are components whose LTR values have been ignored.
> 
> This patch adds the feature to print out such components, if they exist.
> 
> Signed-off-by: Rajat Khandelwal <rajat.khandelwal@...ux.intel.com>
> ---
> 
> v2: kmalloc -> devm_kmalloc
> 
>  drivers/platform/x86/intel/pmc/core.c | 47 ++++++++++++++++++++-------
>  drivers/platform/x86/intel/pmc/core.h |  2 +-
>  2 files changed, 36 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/platform/x86/intel/pmc/core.c b/drivers/platform/x86/intel/pmc/core.c
> index 3a15d32d7644..d4196b10b8af 100644
> --- a/drivers/platform/x86/intel/pmc/core.c
> +++ b/drivers/platform/x86/intel/pmc/core.c
> @@ -53,6 +53,14 @@ const struct pmc_bit_map msr_map[] = {
>  	{}
>  };
>  
> +struct ltr_entry {
> +	u32 comp_index;
> +	const char *comp_name;
> +	struct list_head node;
> +};
> +
> +static LIST_HEAD(ltr_ignore_list);

You need to add a static mutex here to protect this list and then take
that mutex in places where you modify or read the list.

Regards,

Hans



> +
>  static inline u32 pmc_core_reg_read(struct pmc_dev *pmcdev, int reg_offset)
>  {
>  	return readl(pmcdev->regbase + reg_offset);
> @@ -435,27 +443,18 @@ static int pmc_core_pll_show(struct seq_file *s, void *unused)
>  }
>  DEFINE_SHOW_ATTRIBUTE(pmc_core_pll);
>  
> -int pmc_core_send_ltr_ignore(struct pmc_dev *pmcdev, u32 value)
> +void pmc_core_send_ltr_ignore(struct pmc_dev *pmcdev, u32 value)
>  {
>  	const struct pmc_reg_map *map = pmcdev->map;
>  	u32 reg;
> -	int err = 0;
>  
>  	mutex_lock(&pmcdev->lock);
>  
> -	if (value > map->ltr_ignore_max) {
> -		err = -EINVAL;
> -		goto out_unlock;
> -	}
> -
>  	reg = pmc_core_reg_read(pmcdev, map->ltr_ignore_offset);
>  	reg |= BIT(value);
>  	pmc_core_reg_write(pmcdev, map->ltr_ignore_offset, reg);
>  
> -out_unlock:
>  	mutex_unlock(&pmcdev->lock);
> -
> -	return err;
>  }
>  
>  static ssize_t pmc_core_ltr_ignore_write(struct file *file,
> @@ -464,6 +463,8 @@ static ssize_t pmc_core_ltr_ignore_write(struct file *file,
>  {
>  	struct seq_file *s = file->private_data;
>  	struct pmc_dev *pmcdev = s->private;
> +	const struct pmc_reg_map *map = pmcdev->map;
> +	struct ltr_entry *entry;
>  	u32 buf_size, value;
>  	int err;
>  
> @@ -473,13 +474,35 @@ static ssize_t pmc_core_ltr_ignore_write(struct file *file,
>  	if (err)
>  		return err;
>  
> -	err = pmc_core_send_ltr_ignore(pmcdev, value);
> +	if (value > map->ltr_ignore_max)
> +		return -EINVAL;
>  
> -	return err == 0 ? count : err;
> +	list_for_each_entry(entry, &ltr_ignore_list, node) {
> +		if (entry->comp_index == value)
> +			return -EEXIST;
> +	}
> +
> +	entry = devm_kmalloc(&pmcdev->pdev->dev, sizeof(*entry), GFP_KERNEL);
> +	if (!entry)
> +		return -ENOMEM;
> +
> +	entry->comp_name = map->ltr_show_sts[value].name;
> +	entry->comp_index = value;
> +	list_add_tail(&entry->node, &ltr_ignore_list);
> +
> +	pmc_core_send_ltr_ignore(pmcdev, value);
> +
> +	return count;
>  }
>  
>  static int pmc_core_ltr_ignore_show(struct seq_file *s, void *unused)
>  {
> +	struct ltr_entry *entry;
> +
> +	list_for_each_entry(entry, &ltr_ignore_list, node) {
> +		seq_printf(s, "%s\n", entry->comp_name);
> +	}
> +
>  	return 0;
>  }
>  
> diff --git a/drivers/platform/x86/intel/pmc/core.h b/drivers/platform/x86/intel/pmc/core.h
> index 810204d758ab..da35b0fcbe6e 100644
> --- a/drivers/platform/x86/intel/pmc/core.h
> +++ b/drivers/platform/x86/intel/pmc/core.h
> @@ -396,7 +396,7 @@ extern const struct pmc_reg_map adl_reg_map;
>  extern const struct pmc_reg_map mtl_reg_map;
>  
>  extern void pmc_core_get_tgl_lpm_reqs(struct platform_device *pdev);
> -extern int pmc_core_send_ltr_ignore(struct pmc_dev *pmcdev, u32 value);
> +extern void pmc_core_send_ltr_ignore(struct pmc_dev *pmcdev, u32 value);
>  
>  void spt_core_init(struct pmc_dev *pmcdev);
>  void cnp_core_init(struct pmc_dev *pmcdev);