linux-kernel - Re: [PATCH 3/3] ACPI: Change NFIT driver to set PMEM type to iomem entry

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Date:	Fri, 12 Feb 2016 11:41:04 -0800
From:	Dan Williams <dan.j.williams@...el.com>
To:	Toshi Kani <toshi.kani@....com>
Cc:	Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...e.de>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"linux-nvdimm@...ts.01.org" <linux-nvdimm@...ts.01.org>,
	Linux ACPI <linux-acpi@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/3] ACPI: Change NFIT driver to set PMEM type to iomem entry

On Tue, Feb 2, 2016 at 10:55 AM, Toshi Kani <toshi.kani@....com> wrote:
> Change acpi_nfit_register_region() to call iomem_set_desc() with
> IORES_DESC_PERSISTENT_MEMORY for NFIT_SPA_PM ranges found in ACPI
> NFIT table.
>
> When FW sets E820_PMEM in e820 and EFI_PERSISTENT_MEMORY in EFI,
> this code simply sets PMEM type again to "Persistent Memory" entries
> in the iomem table.  When FW sets reserved type for persistent
> memory ranges, it sets PMEM type to "reserved" entries covering
> PMEM ranges.
>
> This allows the EINJ driver, which calls region_intersects() with
> IORES_DESC_PERSISTENT_MEMORY to check persistent memory ranges,
> to work continuously even if FW sets reserved type to persistent
> memory in e820 and EFI.
>
> Signed-off-by: Toshi Kani <toshi.kani@....com>
> Cc: Rafael J. Wysocki <rjw@...ysocki.net>
> Cc: Dan Williams <dan.j.williams@...el.com>
> Cc: Ingo Molnar <mingo@...nel.org>
> Cc: Borislav Petkov <bp@...e.de>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> ---
>  drivers/acpi/nfit.c |    6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/drivers/acpi/nfit.c b/drivers/acpi/nfit.c
> index ad6d8c6..add04f0 100644
> --- a/drivers/acpi/nfit.c
> +++ b/drivers/acpi/nfit.c
> @@ -1781,6 +1781,12 @@ static int acpi_nfit_register_region(struct acpi_nfit_desc *acpi_desc,
>
>         nvdimm_bus = acpi_desc->nvdimm_bus;
>         if (nfit_spa_type(spa) == NFIT_SPA_PM) {
> +               rc = iomem_set_desc(spa->address, spa->length,
> +                                       IORES_DESC_PERSISTENT_MEMORY);
> +               if (rc)
> +                       dev_dbg(acpi_desc->dev,
> +                               "error setting iomem desc: %d\n", rc);
> +

Hmm, if we set the type on driver load, should we clear the type on
driver unload?

Actually it might be more straightforward to specify a type at
request_region() time.  That way it gets released at release_region().
We're already setting a resource name at request_region time, adding a
type annotation at the time seems appropriate.