Date:	Mon, 8 Feb 2016 14:10:58 -0500
From:	Linda Knippers <linda.knippers@....com>
To:	Dan Williams <dan.j.williams@...el.com>, linux-nvdimm@...ts.01.org
Cc:	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Subject: Re: [PATCH 1/3] nfit: fix multi-interface dimm handling, acpi6.1
 compatibility

On 2/8/2016 1:30 PM, Dan Williams wrote:
> ACPI 6.1 clarified that multi-interface dimms require multiple control
> region entries (DCRs) per dimm.  Previously we were assuming that a
> control region is only present when block-data-windows are present.

We need to give this a quick test with NVDIMM-N because those types of
NVDIMMs have control regions without block-data-windows.  We've fixed
bugs related to that assumption a couple of times.

> This implementation was done with an eye to be compatibility with the
> looser ACPI 6.0 interpretation of this table.
> 
> 1/ When coalescing the memory device (MEMDEV) tables for a single dimm,
> coalesce on device_handle rather than control region index.
> 
> 2/ Whenever we disocver a control region with non-zero block windows
discover

> re-scan for block-data-window (BDW) entries.
> 
> We may need to revisit this if a DIMM ever implements a format interface
> outside of blk or pmem, but that is not on the foreseeable horizon.
> 
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Dan Williams <dan.j.williams@...el.com>
> ---
>  drivers/acpi/nfit.c |   71 +++++++++++++++++++++++++--------------------------
>  1 file changed, 35 insertions(+), 36 deletions(-)
> 
> diff --git a/drivers/acpi/nfit.c b/drivers/acpi/nfit.c
> index ad6d8c6b777e..424b362e8fdc 100644
> --- a/drivers/acpi/nfit.c
> +++ b/drivers/acpi/nfit.c
> @@ -469,37 +469,16 @@ static void nfit_mem_find_spa_bdw(struct acpi_nfit_desc *acpi_desc,
>  	nfit_mem->bdw = NULL;
>  }
>  
> -static int nfit_mem_add(struct acpi_nfit_desc *acpi_desc,
> +static void nfit_mem_init_bdw(struct acpi_nfit_desc *acpi_desc,
>  		struct nfit_mem *nfit_mem, struct acpi_nfit_system_address *spa)
>  {
>  	u16 dcr = __to_nfit_memdev(nfit_mem)->region_index;
>  	struct nfit_memdev *nfit_memdev;
>  	struct nfit_flush *nfit_flush;
> -	struct nfit_dcr *nfit_dcr;
>  	struct nfit_bdw *nfit_bdw;
>  	struct nfit_idt *nfit_idt;
>  	u16 idt_idx, range_index;
>  
> -	list_for_each_entry(nfit_dcr, &acpi_desc->dcrs, list) {
> -		if (nfit_dcr->dcr->region_index != dcr)
> -			continue;
> -		nfit_mem->dcr = nfit_dcr->dcr;
> -		break;
> -	}
> -
> -	if (!nfit_mem->dcr) {
> -		dev_dbg(acpi_desc->dev, "SPA %d missing:%s%s\n",
> -				spa->range_index, __to_nfit_memdev(nfit_mem)
> -				? "" : " MEMDEV", nfit_mem->dcr ? "" : " DCR");
> -		return -ENODEV;
> -	}
> -
> -	/*
> -	 * We've found enough to create an nvdimm, optionally
> -	 * find an associated BDW
> -	 */
> -	list_add(&nfit_mem->list, &acpi_desc->dimms);
> -
>  	list_for_each_entry(nfit_bdw, &acpi_desc->bdws, list) {
>  		if (nfit_bdw->bdw->region_index != dcr)
>  			continue;
> @@ -508,12 +487,12 @@ static int nfit_mem_add(struct acpi_nfit_desc *acpi_desc,
>  	}
>  
>  	if (!nfit_mem->bdw)
> -		return 0;
> +		return;
>  
>  	nfit_mem_find_spa_bdw(acpi_desc, nfit_mem);
>  
>  	if (!nfit_mem->spa_bdw)
> -		return 0;
> +		return;
>  
>  	range_index = nfit_mem->spa_bdw->range_index;
>  	list_for_each_entry(nfit_memdev, &acpi_desc->memdevs, list) {
> @@ -538,8 +517,6 @@ static int nfit_mem_add(struct acpi_nfit_desc *acpi_desc,
>  		}
>  		break;
>  	}
> -
> -	return 0;
>  }
>  
>  static int nfit_mem_dcr_init(struct acpi_nfit_desc *acpi_desc,
> @@ -548,7 +525,6 @@ static int nfit_mem_dcr_init(struct acpi_nfit_desc *acpi_desc,
>  	struct nfit_mem *nfit_mem, *found;
>  	struct nfit_memdev *nfit_memdev;
>  	int type = nfit_spa_type(spa);
> -	u16 dcr;
>  
>  	switch (type) {
>  	case NFIT_SPA_DCR:
> @@ -559,14 +535,18 @@ static int nfit_mem_dcr_init(struct acpi_nfit_desc *acpi_desc,
>  	}
>  
>  	list_for_each_entry(nfit_memdev, &acpi_desc->memdevs, list) {
> -		int rc;
> +		struct nfit_dcr *nfit_dcr;
> +		u32 device_handle;
> +		u16 dcr;
>  
>  		if (nfit_memdev->memdev->range_index != spa->range_index)
>  			continue;
>  		found = NULL;
>  		dcr = nfit_memdev->memdev->region_index;
> +		device_handle = nfit_memdev->memdev->device_handle;
>  		list_for_each_entry(nfit_mem, &acpi_desc->dimms, list)
> -			if (__to_nfit_memdev(nfit_mem)->region_index == dcr) {
> +			if (__to_nfit_memdev(nfit_mem)->device_handle
> +					== device_handle) {
>  				found = nfit_mem;
>  				break;
>  			}
> @@ -579,6 +559,31 @@ static int nfit_mem_dcr_init(struct acpi_nfit_desc *acpi_desc,
>  			if (!nfit_mem)
>  				return -ENOMEM;
>  			INIT_LIST_HEAD(&nfit_mem->list);
> +			list_add(&nfit_mem->list, &acpi_desc->dimms);
> +		}
> +
> +		list_for_each_entry(nfit_dcr, &acpi_desc->dcrs, list) {
> +			if (nfit_dcr->dcr->region_index != dcr)
> +				continue;
> +			/*
> +			 * Record the control region for the dimm.  For
> +			 * the ACPI 6.1 case, where there are separate
> +			 * control regions for the pmem vs blk
> +			 * interfaces, be sure to record the extended
> +			 * blk details.
> +			 */
> +			if (!nfit_mem->dcr)
> +				nfit_mem->dcr = nfit_dcr->dcr;
> +			else if (nfit_mem->dcr->windows == 0
> +					&& nfit_dcr->dcr->windows)
> +				nfit_mem->dcr = nfit_dcr->dcr;
> +			break;
> +		}
> +
> +		if (dcr && !nfit_mem->dcr) {
> +			dev_err(acpi_desc->dev, "SPA %d missing DCR %d\n",
> +					spa->range_index, dcr);
> +			return -ENODEV;
>  		}
>  
>  		if (type == NFIT_SPA_DCR) {
> @@ -595,6 +600,7 @@ static int nfit_mem_dcr_init(struct acpi_nfit_desc *acpi_desc,
>  				nfit_mem->idt_dcr = nfit_idt->idt;
>  				break;
>  			}
> +			nfit_mem_init_bdw(acpi_desc, nfit_mem, spa);
>  		} else {
>  			/*
>  			 * A single dimm may belong to multiple SPA-PM
> @@ -603,13 +609,6 @@ static int nfit_mem_dcr_init(struct acpi_nfit_desc *acpi_desc,
>  			 */
>  			nfit_mem->memdev_pmem = nfit_memdev->memdev;
>  		}
> -
> -		if (found)
> -			continue;
> -
> -		rc = nfit_mem_add(acpi_desc, nfit_mem, spa);
> -		if (rc)
> -			return rc;
>  	}
>  
>  	return 0;
> 
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> Linux-nvdimm@...ts.01.org
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> 

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