linux-kernel - Re: [PATCH V2] platform/x86: intel_pmc_core: Add CNP SLPS0 debug registers

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Date:   Thu, 31 May 2018 21:38:19 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     "David E. Box" <david.e.box@...ux.intel.com>
Cc:     Andy Shevchenko <andy@...radead.org>,
        Rajneesh Bhardwaj <rajneesh.bhardwaj@...el.com>,
        Vishwanath Somayaji <vishwanath.somayaji@...el.com>,
        Darren Hart <dvhart@...radead.org>,
        kyle.d.pelton@...ux.intel.com,
        Platform Driver <platform-driver-x86@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V2] platform/x86: intel_pmc_core: Add CNP SLPS0 debug registers

On Fri, May 25, 2018 at 4:10 AM, David E. Box
<david.e.box@...ux.intel.com> wrote:
> Adds debugfs access to registers in the Cannon Point PCH PMC that are
> useful for debugging #SLP_S0 signal assertion and other low power related
> activities. Device pm states are latched in these registers whenever the
> package enters C10 and can be read from slp_s0_debug_status. The pm
> states may also be latched by writing 1 to slp_s0_dbg_latch which will
> immediately capture the current state on the next read of
> slp_s0_debug_status. Also while in intel_pmc_core.h clean up spacing.
>

Thanks for an update. My comments below.

As far as I understand there is still ongoing discussion about the
approach when and how to show data. So I'll wait a bit for a
settlement between you, guys.

> +static void pmc_core_slps0_dbg_latch(struct pmc_dev *pmcdev, bool reset)
> +{
> +       const struct pmc_reg_map *map = pmcdev->map;
> +       u32 fd;
> +
> +       mutex_lock(&pmcdev->lock);
> +
> +       if (!reset && !slps0_dbg_latch)
> +               goto out_unlock;
> +
> +       fd = pmc_core_reg_read(pmcdev, map->slps0_dbg_offset);

> +       reset ? (fd &= ~CNP_PMC_LATCH_SLPS0_EVENTS) :
> +               (fd |= CNP_PMC_LATCH_SLPS0_EVENTS);

I would rather use classical pattern here, i.e.

if (reset)
 fd ...
else
 fd ...

> +       pmc_core_reg_write(pmcdev, map->slps0_dbg_offset, fd);
> +
> +       slps0_dbg_latch = 0;
> +
> +out_unlock:
> +       mutex_unlock(&pmcdev->lock);
> +}

> +       struct pmc_dev *pmcdev = s ? s->private : &pmc;

I'm not sure why do we need such condition.

Simple

... pmcdev = s->private;

is enough.

>  /* Cannonlake Power Management Controller register offsets */
> -#define CNP_PMC_SLP_S0_RES_COUNTER_OFFSET      0x193C
> -#define CNP_PMC_LTR_IGNORE_OFFSET              0x1B0C
> -#define CNP_PMC_PM_CFG_OFFSET                  0x1818
> +#define CNP_PMC_SLP_S0_RES_COUNTER_OFFSET      0x193C
> +#define CNP_PMC_LTR_IGNORE_OFFSET              0x1B0C
> +#define CNP_PMC_PM_CFG_OFFSET                  0x1818

I have hard time to understand what is the difference here.
Either do another clean up patch (white spaces vs. tabs?) or leave it untouched.

>  /* Cannonlake: PGD PFET Enable Ack Status Register(s) start */
> -#define CNP_PMC_HOST_PPFEAR0A                  0x1D90
> +#define CNP_PMC_HOST_PPFEAR0A                  0x1D90
>
> -#define CNP_PMC_MMIO_REG_LEN                   0x2000
> -#define CNP_PPFEAR_NUM_ENTRIES                 8
> -#define CNP_PMC_READ_DISABLE_BIT               22
> +#define CNP_PMC_MMIO_REG_LEN                   0x2000
> +#define CNP_PPFEAR_NUM_ENTRIES                 8
> +#define CNP_PMC_READ_DISABLE_BIT               22

Ditto.

> +struct slps0_dbg_map {
> +       const struct pmc_bit_map *slps0_dbg_sts;
> +       int size;
> +};

Didn't pay attention to this earlier. Why do we have a separate size
member? What does it define?

-- 
With Best Regards,
Andy Shevchenko