linux-kernel - Re: [PATCH v8 3/4] fpga: dfl: add basic support for DFHv1

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Message-ID: <Y61kb9OGikxLvAcr@smile.fi.intel.com>
Date:   Thu, 29 Dec 2022 11:57:03 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     matthew.gerlach@...ux.intel.com
Cc:     hao.wu@...el.com, yilun.xu@...el.com, russell.h.weight@...el.com,
        basheer.ahmed.muddebihal@...el.com, trix@...hat.com,
        mdf@...nel.org, linux-fpga@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        tianfei.zhang@...el.com, corbet@....net,
        gregkh@...uxfoundation.org, linux-serial@...r.kernel.org,
        jirislaby@...nel.org, geert+renesas@...der.be,
        niklas.soderlund+renesas@...natech.se, macro@...am.me.uk,
        johan@...nel.org, lukas@...ner.de, ilpo.jarvinen@...ux.intel.com,
        marpagan@...hat.com, bagasdotme@...il.com
Subject: Re: [PATCH v8 3/4] fpga: dfl: add basic support for DFHv1

On Wed, Dec 28, 2022 at 10:16:23AM -0800, matthew.gerlach@...ux.intel.com wrote:
> From: Matthew Gerlach <matthew.gerlach@...ux.intel.com>
> 
> Version 1 of the Device Feature Header (DFH) definition adds
> functionality to the DFL bus.
> 
> A DFHv1 header may have one or more parameter blocks that
> further describes the HW to SW.  Add support to the DFL bus

Single space is enough.

> to parse the MSI-X parameter.
> 
> The location of a feature's register set is explicitly
> described in DFHv1 and can be relative to the base of the DFHv1
> or an absolute address.  Parse the location and pass the information
> to DFL driver.

I'm wondering what DFL states for.

...

> +/**
> + * dfh_get_u64_param_vals() - get array of u64 param values for given parameter id
> + * @dfl_dev: dfl device
> + * @param: id of dfl parameter
> + * @pval: location of parameter data destination
> + * @nvals: number of u64 elements of parameter data
> + *
> + * Return: pointer to start of parameter block, PTR_ERR otherwise
> + */
> +u64 *dfh_get_u64_param_vals(struct dfl_device *dfl_dev, int param_id, u64 *pval, int nvals)
> +{
> +	u64 *param = find_param(dfl_dev->params, dfl_dev->param_size, param_id);
> +	u64 next;
> +	int i;
> +
> +	if (!param)
> +		return ERR_PTR(-ENOENT);
> +
> +	next = FIELD_GET(DFHv1_PARAM_HDR_NEXT_OFFSET, *param);
> +
> +	if (nvals >= next)
> +		return ERR_PTR(-ENOMEM);

ENODATA ?

> +	for (i = 0; i < nvals; i++)
> +		*pval++ = param[i + 1];

memcpy() ?

> +	return param;
> +}

...

> +	finfo = kzalloc(struct_size(finfo, params, dfh_psize/sizeof(u64)), GFP_KERNEL);

' / ' (mind the spaces)

Also, perhaps better to use sizeof(*params) or what is the member of that
structure. So it will be more robust against possible changes.

>  	if (!finfo)
>  		return -ENOMEM;

-- 
With Best Regards,
Andy Shevchenko