linux-kernel - RE: [PATCH v6 3/6] fpga: dfl: check released_port_num and num

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Message-ID: <DM6PR11MB381950AC46C7913128AE212D85129@DM6PR11MB3819.namprd11.prod.outlook.com>
Date:   Thu, 17 Mar 2022 08:49:16 +0000
From:   "Wu, Hao" <hao.wu@...el.com>
To:     "Zhang, Tianfei" <tianfei.zhang@...el.com>,
        "trix@...hat.com" <trix@...hat.com>,
        "mdf@...nel.org" <mdf@...nel.org>,
        "Xu, Yilun" <yilun.xu@...el.com>,
        "linux-fpga@...r.kernel.org" <linux-fpga@...r.kernel.org>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "rdunlap@...radead.org" <rdunlap@...radead.org>
CC:     "corbet@....net" <corbet@....net>,
        Matthew Gerlach <matthew.gerlach@...ux.intel.com>
Subject: RE: [PATCH v6 3/6] fpga: dfl: check released_port_num and num_vfs for
 legacy model

> Subject: [PATCH v6 3/6] fpga: dfl: check released_port_num and num_vfs for
> legacy model
> 
> From: Tianfei zhang <tianfei.zhang@...el.com>
> 
> In OFS legacy model, there is 1:1 mapping for Port device and VF,
> so it need to check the number of released port match the number of
> VFs or not. But in "Multiple VFs per PR slot" model, there is 1:N
> mapping for the Port device and VFs.

The title and commit message seems not matching the code..
>From code it sounds like we are trying to skip the PORT 
(PF access-> VF access) function, as new SRIOV usage model is introduced.
Probably we can skip it early in this function or even skip this function
directly. It doesn't matter it's 1:N or 1:1, we always want to keep PF
access to port, right?

> 
> Signed-off-by: Matthew Gerlach <matthew.gerlach@...ux.intel.com>
> Signed-off-by: Tianfei zhang <tianfei.zhang@...el.com>
> ---
>  drivers/fpga/dfl.c | 10 ++++++----
>  drivers/fpga/dfl.h |  2 ++
>  2 files changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c
> index 712c53363fda..b95b29c5c81d 100644
> --- a/drivers/fpga/dfl.c
> +++ b/drivers/fpga/dfl.c
> @@ -1707,11 +1707,13 @@ int dfl_fpga_cdev_config_ports_vf(struct
> dfl_fpga_cdev *cdev, int num_vfs)
> 
>  	mutex_lock(&cdev->lock);
>  	/*
> -	 * can't turn multiple ports into 1 VF device, only 1 port for 1 VF
> -	 * device, so if released port number doesn't match VF device number,
> -	 * then reject the request with -EINVAL error code.
> +	 * In the OFS legacy model, it can't turn multiple ports into 1 VF
> +	 * device, because only 1 port conneced to 1 VF device, so if released
> +	 * port number doesn't match VF device number, then reject the request
> +	 * with -EINVAL error code.
>  	 */
> -	if (cdev->released_port_num != num_vfs) {
> +	if ((dfl_has_port_connected_afu(cdev) &&

Could we really use this as indication for which SRIOV model of hardware?

> +	     cdev->released_port_num != num_vfs)) {
>  		ret = -EINVAL;
>  		goto done;
>  	}
> diff --git a/drivers/fpga/dfl.h b/drivers/fpga/dfl.h
> index bc56b7e8c01b..83c2c50975e5 100644
> --- a/drivers/fpga/dfl.h
> +++ b/drivers/fpga/dfl.h
> @@ -471,6 +471,8 @@ void dfl_fpga_enum_info_free(struct
> dfl_fpga_enum_info *info);
>  #define DFL_PORT_CONNECT_BITS  MAX_DFL_FPGA_PORT_NUM
>  #define DFL_FEAT_PORT_CONNECT_MASK ((1UL <<
> (DFL_PORT_CONNECT_BITS)) - 1)
> 
> +#define dfl_has_port_connected_afu(cdev) ((cdev)->flags &
> DFL_FEAT_PORT_CONNECT_MASK)
> +
>  /**
>   * struct dfl_fpga_cdev - container device of DFL based FPGA
>   *
> --
> 2.26.2