netdev - Re: [PATCH v7 05/24] wfx: add main.c/main.h

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Date:   Fri, 01 Oct 2021 12:22:08 +0300
From:   Kalle Valo <kvalo@...eaurora.org>
To:     Jerome Pouiller <Jerome.Pouiller@...abs.com>
Cc:     linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "David S . Miller" <davem@...emloft.net>,
        devicetree@...r.kernel.org, Rob Herring <robh+dt@...nel.org>,
        linux-mmc@...r.kernel.org,
        Pali Rohár <pali@...nel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>
Subject: Re: [PATCH v7 05/24] wfx: add main.c/main.h

Jerome Pouiller <Jerome.Pouiller@...abs.com> writes:

> From: Jérôme Pouiller <jerome.pouiller@...abs.com>
>
> Signed-off-by: Jérôme Pouiller <jerome.pouiller@...abs.com>

[...]

> +/* The device needs data about the antenna configuration. This information in
> + * provided by PDS (Platform Data Set, this is the wording used in WF200
> + * documentation) files. For hardware integrators, the full process to create
> + * PDS files is described here:
> + *   https:github.com/SiliconLabs/wfx-firmware/blob/master/PDS/README.md
> + *
> + * So this function aims to send PDS to the device. However, the PDS file is
> + * often bigger than Rx buffers of the chip, so it has to be sent in multiple
> + * parts.
> + *
> + * In add, the PDS data cannot be split anywhere. The PDS files contains tree
> + * structures. Braces are used to enter/leave a level of the tree (in a JSON
> + * fashion). PDS files can only been split between root nodes.
> + */
> +int wfx_send_pds(struct wfx_dev *wdev, u8 *buf, size_t len)
> +{
> +	int ret;
> +	int start, brace_level, i;
> +
> +	start = 0;
> +	brace_level = 0;
> +	if (buf[0] != '{') {
> + dev_err(wdev->dev, "valid PDS start with '{'. Did you forget to
> compress it?\n");
> +		return -EINVAL;
> +	}
> +	for (i = 1; i < len - 1; i++) {
> +		if (buf[i] == '{')
> +			brace_level++;
> +		if (buf[i] == '}')
> +			brace_level--;
> +		if (buf[i] == '}' && !brace_level) {
> +			i++;
> +			if (i - start + 1 > WFX_PDS_MAX_SIZE)
> +				return -EFBIG;
> +			buf[start] = '{';
> +			buf[i] = 0;
> +			dev_dbg(wdev->dev, "send PDS '%s}'\n", buf + start);
> +			buf[i] = '}';
> +			ret = hif_configuration(wdev, buf + start,
> +						i - start + 1);
> +			if (ret > 0) {
> + dev_err(wdev->dev, "PDS bytes %d to %d: invalid data (unsupported
> options?)\n",
> +					start, i);
> +				return -EINVAL;
> +			}
> +			if (ret == -ETIMEDOUT) {
> + dev_err(wdev->dev, "PDS bytes %d to %d: chip didn't reply (corrupted
> file?)\n",
> +					start, i);
> +				return ret;
> +			}
> +			if (ret) {
> + dev_err(wdev->dev, "PDS bytes %d to %d: chip returned an unknown
> error\n",
> +					start, i);
> +				return -EIO;
> +			}
> +			buf[i] = ',';
> +			start = i;
> +		}
> +	}
> +	return 0;
> +}

I'm not really fond of having this kind of ASCII based parser in the
kernel. Do you have an example compressed file somewhere?

Does the device still work without these PDS files? I ask because my
suggestion is to remove this part altogether and revisit after the
initial driver is moved to drivers/net/wireless. A lot simpler to review
complex features separately.

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