linux-kernel - Re: [PATCH v1 6/7] fpga: dfl: Handle dfl's starting with AFU

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Date:   Tue, 15 Feb 2022 08:09:49 -0800
From:   Tom Rix <trix@...hat.com>
To:     Tianfei zhang <tianfei.zhang@...el.com>, hao.wu@...el.com,
        mdf@...nel.org, yilun.xu@...el.com, linux-fpga@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     corbet@....net, Matthew Gerlach <matthew.gerlach@...ux.intel.com>
Subject: Re: [PATCH v1 6/7] fpga: dfl: Handle dfl's starting with AFU


On 2/14/22 3:26 AM, Tianfei zhang wrote:
> From: Matthew Gerlach <matthew.gerlach@...ux.intel.com>
>
> Allow for a Device Feature List (DFL) to start with
> a Device Feature Header (DFH) of type Accelerator Function Unit (AFU)
> by doing nothing.  This allows for PCIe VFs to be created.
>
> Signed-off-by: Matthew Gerlach <matthew.gerlach@...ux.intel.com>
> Signed-off-by: Tianfei Zhang <tianfei.zhang@...el.com>
> ---
>   drivers/fpga/dfl-pci.c |  7 ++++++-
>   drivers/fpga/dfl.c     | 23 ++++++++++++++---------
>   2 files changed, 20 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/fpga/dfl-pci.c b/drivers/fpga/dfl-pci.c
> index 8abd9b408403..83b604d6dbe6 100644
> --- a/drivers/fpga/dfl-pci.c
> +++ b/drivers/fpga/dfl-pci.c
> @@ -277,7 +277,12 @@ static int find_dfls_by_default(struct pci_dev *pcidev,
>   
>   		dfl_fpga_enum_info_add_dfl(info, start, len);
>   	} else {
> -		ret = -ENODEV;
> +		v = readq(base + DFH);

This isn't likely to work on older cards.

Is there there a version to key off of ?

Tom

> +		if (FIELD_GET(DFH_TYPE, v) != DFH_TYPE_AFU) {
> +			dev_info(&pcidev->dev, "Unknown feature type 0x%llx id 0x%llx\n",
> +				 FIELD_GET(DFH_TYPE, v), FIELD_GET(DFH_ID, v));
> +			ret = -ENODEV;
> +		}
>   	}
>   
>   	/* release I/O mappings for next step enumeration */
> diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c
> index a5263ac258c5..25bd24a4cca0 100644
> --- a/drivers/fpga/dfl.c
> +++ b/drivers/fpga/dfl.c
> @@ -900,9 +900,11 @@ static void build_info_free(struct build_feature_devs_info *binfo)
>   		dfl_id_free(feature_dev_id_type(binfo->feature_dev),
>   			    binfo->feature_dev->id);
>   
> -		list_for_each_entry_safe(finfo, p, &binfo->sub_features, node) {
> -			list_del(&finfo->node);
> -			kfree(finfo);
> +		if (!list_empty(&binfo->sub_features)) {
> +			list_for_each_entry_safe(finfo, p, &binfo->sub_features, node) {
> +				list_del(&finfo->node);
> +				kfree(finfo);
> +			}
>   		}
>   	}
>   
> @@ -1437,6 +1439,7 @@ dfl_fpga_feature_devs_enumerate(struct dfl_fpga_enum_info *info)
>   
>   	binfo->dev = info->dev;
>   	binfo->cdev = cdev;
> +	INIT_LIST_HEAD(&binfo->sub_features);
>   
>   	binfo->nr_irqs = info->nr_irqs;
>   	if (info->nr_irqs)
> @@ -1446,12 +1449,14 @@ dfl_fpga_feature_devs_enumerate(struct dfl_fpga_enum_info *info)
>   	 * start enumeration for all feature devices based on Device Feature
>   	 * Lists.
>   	 */
> -	list_for_each_entry(dfl, &info->dfls, node) {
> -		ret = parse_feature_list(binfo, dfl->start, dfl->len);
> -		if (ret) {
> -			remove_feature_devs(cdev);
> -			build_info_free(binfo);
> -			goto unregister_region_exit;
> +	if (!list_empty(&info->dfls)) {
> +		list_for_each_entry(dfl, &info->dfls, node) {
> +			ret = parse_feature_list(binfo, dfl->start, dfl->len);
> +			if (ret) {
> +				remove_feature_devs(cdev);
> +				build_info_free(binfo);
> +				goto unregister_region_exit;
> +			}
>   		}
>   	}
>