Re: [PATCH] identify firmware version

[Dmitry Torokhov]

Hi Rafi,

On Mon, Sep 06, 2010 at 12:42:42PM -0400, Rafi Rubin wrote:
> This adds firmware version polling to the end of probe and reports the
> version both in the raw form and proccessed to match the formatting used
> by N-Trig.
> 
> Signed-off-by: Rafi Rubin <rafi@xxxxxxxxxxxxxx>
> ---
>  drivers/hid/hid-ntrig.c |   56 +++++++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 56 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/hid/hid-ntrig.c b/drivers/hid/hid-ntrig.c
> index 43e95de..3472b3b 100644
> --- a/drivers/hid/hid-ntrig.c
> +++ b/drivers/hid/hid-ntrig.c
> @@ -90,6 +90,26 @@ struct ntrig_data {
>  };
>  
>  
> +/*
> + * This function converts the 4 byte raw firmware code into
> + * a string containing 5 comma separated numbers.
> + */
> +static int ntrig_version_string(unsigned char *raw, char *buf)
> +{
> +	__u8 a =  (raw[1] & 0x0e) >> 1;
> +	__u8 b =  (raw[0] & 0x3c) >> 2;
> +	__u8 c = ((raw[0] & 0x03) << 3) | ((raw[3] & 0xe0) >> 5);
> +	__u8 d = ((raw[3] & 0x07) << 3) | ((raw[2] & 0xe0) >> 5);
> +	__u8 e =   raw[2] & 0x07;
> +
> +	/*
> +	 * As yet unmapped bits:
> +	 * 0b11000000 0b11110001 0b00011000 0b00011000
> +	 */
> +
> +	return sprintf(buf, "%u.%u.%u.%u.%u", a, b, c, d, e);
> +}
> +
>  static ssize_t show_phys_width(struct device *dev,
>  			       struct device_attribute *attr,
>  			       char *buf)
> @@ -776,6 +796,9 @@ static int ntrig_probe(struct hid_device *hdev, const struct hid_device_id *id)
>  	struct hid_input *hidinput;
>  	struct input_dev *input;
>  	struct hid_report *report;
> +	unsigned char *data;
> +	struct usb_device *usb_dev = hid_to_usb_dev(hdev);
> +	char *buf;
>  
>  	if (id->driver_data)
>  		hdev->quirks |= HID_QUIRK_MULTI_INPUT;
> @@ -848,10 +871,43 @@ static int ntrig_probe(struct hid_device *hdev, const struct hid_device_id *id)
>  	if (report)
>  		usbhid_submit_report(hdev, report, USB_DIR_OUT);
>  
> +	data = kmalloc(8, GFP_KERNEL);
> +	if (!data) {
> +		ret = -ENOMEM;
> +		goto err_free;
> +	}
> +
> +	ret = usb_control_msg(usb_dev, usb_rcvctrlpipe(usb_dev, 0),
> +			      USB_REQ_CLEAR_FEATURE,
> +			      USB_TYPE_CLASS | USB_RECIP_INTERFACE |
> +			      USB_DIR_IN,
> +			      0x30c, 1, data, 8,
> +			      USB_CTRL_SET_TIMEOUT);
> +
> +	if (ret == 8) {
> +		buf = kmalloc(20, GFP_KERNEL);
> +		if (!buf) {
> +			ret = -ENOMEM;
> +			goto err_free_data;
> +		}

Why do you allocate this from heap? Surely we can spare 20 bytes on
stack (you aren't doing DMA into it).

I'd also split all this code into ntrig_report_version() to simplifu
error handling here.

> +
> +		ret = ntrig_version_string(&data[2], buf);
> +
> +		dev_info(&hdev->dev,
> +			 "Firmware version: %s (%02x%02x %02x%02x)\n",
> +			 buf, data[2], data[3], data[4], data[5]);
> +
> +		kfree(buff);
> +	}
> +
>  	ret = sysfs_create_group(&hdev->dev.kobj,
>  			&ntrig_attribute_group);
>  
> +	kfree(data);
> +
>  	return 0;
> +err_free_data:
> +	kfree(data);
>  err_free:
>  	kfree(nd);
>  	return ret;
> -- 
> 1.7.1
> 

-- 
Dmitry
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