linux-kernel - Re: [PATCH V5 19/20] platform/x86/intel/pmc: Add debug attribute for Die C6 counter

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Message-ID: <5b3b7eb7-78c-c9ec-2acd-f54ff116188@linux.intel.com>
Date:   Thu, 23 Nov 2023 13:38:57 +0200 (EET)
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     "David E. Box" <david.e.box@...ux.intel.com>
cc:     LKML <linux-kernel@...r.kernel.org>,
        platform-driver-x86@...r.kernel.org, rajvi.jingar@...ux.intel.com
Subject: Re: [PATCH V5 19/20] platform/x86/intel/pmc: Add debug attribute
 for Die C6 counter

On Wed, 22 Nov 2023, David E. Box wrote:

> Add a "die_c6_us_show" debugfs attribute.  Reads the counter value using
> Intel Platform Monitoring Technology (PMT) driver API. This counter is
> useful for determining the idle residency of CPUs in the compute tile.
> Also adds a missing forward declaration for punit_ep which was declared in
> an earlier upstream commit but only used for the first time in this one.
> 
> Signed-off-by: David E. Box <david.e.box@...ux.intel.com>
> ---
> V5 - Change comment for crystal error and return value
> 
> V4 - no change
> 
> V3 - Split previous PATCH V2 13. Separates implementation (this patch) from
>      platform specific use (next patch)
> 
> V2 - Remove use of __func__
>    - Use HZ_PER_MHZ
>    - Fix missing newlines in printks
> 
>  drivers/platform/x86/intel/pmc/core.c | 55 +++++++++++++++++++++++++++
>  drivers/platform/x86/intel/pmc/core.h |  4 ++
>  2 files changed, 59 insertions(+)
> 
> diff --git a/drivers/platform/x86/intel/pmc/core.c b/drivers/platform/x86/intel/pmc/core.c
> index 4a38d52558fd..fb2c84fba0ae 100644
> --- a/drivers/platform/x86/intel/pmc/core.c
> +++ b/drivers/platform/x86/intel/pmc/core.c

> +static int pmc_core_die_c6_us_show(struct seq_file *s, void *unused)
> +{
> +	struct pmc_dev *pmcdev = s->private;
> +	u64 die_c6_res, count;
> +	int ret;
> +
> +	if (!pmcdev->crystal_freq) {
> +		dev_warn_once(&pmcdev->pdev->dev, "Crystal frequency unavailable\n");
> +		return -ENXIO;
> +	}

I actually started to wonder whether it would be better to just not show 
the file in this case (using .is_visible())? (I'm sorry I forgot to send 
the note about that earlier.)

-- 
 i.