linux-kernel - Re: [PATCH v8 1/3] hwmon: (asus_wmi_ec

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Date:   Mon, 25 Oct 2021 22:37:06 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Denis Pauk <pauk.denis@...il.com>
Cc:     eugene.shalygin@...il.com, platform-driver-x86@...r.kernel.org,
        thomas@...ssschuh.net, Tor Vic <torvic9@...lbox.org>,
        Oleksandr Natalenko <oleksandr@...alenko.name>,
        Jean Delvare <jdelvare@...e.com>,
        Guenter Roeck <linux@...ck-us.net>,
        Jonathan Corbet <corbet@....net>, linux-hwmon@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 1/3] hwmon: (asus_wmi_ec_sensors) Support B550 Asus
 WMI.

On Mon, Oct 25, 2021 at 10:20:17PM +0300, Andy Shevchenko wrote:
> On Fri, Oct 22, 2021 at 11:00:29PM +0300, Denis Pauk wrote:
> > Linux HWMON sensors driver for ASUS motherboards to read
> > sensors from the embedded controller.
> > 
> > Many ASUS motherboards do not publish all the available
> > sensors via the Super I/O chip but the missing ones are
> > available through the embedded controller (EC) registers.
> > 
> > This driver implements reading those sensor data via the
> > WMI method BREC, which is known to be present in all ASUS
> > motherboards based on the AMD 500 series chipsets (and
> > probably is available in other models too). The driver
> > needs to know exact register addresses for the sensors and
> > thus support for each motherboard has to be added explicitly.
> > 
> > The EC registers do not provide critical values for the
> > sensors and as such they are not published to the HWMON.
> > 
> > Supported motherboards:
> > * PRIME X570-PRO
> > * Pro WS X570-ACE
> > * ROG CROSSHAIR VIII HERO
> > * ROG CROSSHAIR VIII DARK HERO
> > * ROG CROSSHAIR VIII FORMULA
> > * ROG STRIX X570-E GAMING
> > * ROG STRIX B550-E GAMING
> 
> Below is a follow up, I have not compiled it.
> Feel free to take fully or partially.

...

> -static int asus_wmi_ec_decode_reply_buffer(const u8 *inp, u8 *out, u32 length)
> +static int asus_wmi_ec_decode_reply_buffer(const u8 *in, u32 length, u8 *out)
>  {
>  	char buffer[ASUSWMI_MAX_BUF_LEN * 2];
> -	const char *pos = buffer;
> -	const u8 *data = inp + 2;
>  	u32 len;
>  
> -	/* Minimum of size of response and size of ACPI result*/
> -	len = min_t(u32, inp[0] / 4, (length - 2) / 4);
> -	len = min_t(u32, len, ASUSWMI_MAX_BUF_LEN);
> +	/* Minimum of size of response and size of ACPI result (in bytes) */
> +	len = min_t(u32, in[0], length - 2);

Of course this should be

        len = min_t(u32, get_unaligned_le16(in), length - 2);

(compare to the opposite below).

> -	utf16s_to_utf8s((wchar_t *)data, len * 2,  UTF16_LITTLE_ENDIAN, buffer, len * 2);
> +	utf16s_to_utf8s((wchar_t *)(in + 2), len / 2, UTF16_LITTLE_ENDIAN, buffer, sizeof(buffer));
>  
> -	return hex2bin(out, pos, len);
> +	return hex2bin(out, buffer, len / 2);
>  }
>  
> -static void asus_wmi_ec_encode_registers(const u16 *registers, u8 len, char *out)
> +static void asus_wmi_ec_encode_registers(const u8 *in, u32 length, char *out)
>  {
>  	char buffer[ASUSWMI_MAX_BUF_LEN * 2];
> -	char *pos = buffer;
> -	unsigned int i;
> -	u8 byte;
> -
> -	*out++ = len * 8;
> -	*out++ = 0;
> -
> -	for (i = 0; i < len; i++) {
> -		byte = registers[i] >> 8;
> -		pos = bin2hex(pos, &byte, 1);
> -		byte = registers[i];
> -		pos = bin2hex(pos, &byte, 1);
> -	}
> +	u16 len = nr_registers * 2;
> +
> +	put_unaligned_le16(len * 2, out);
> +
> +	bin2hex(buffer, in, len);
>  
> -	utf8s_to_utf16s(buffer, len * 4, UTF16_LITTLE_ENDIAN, (wchar_t *)out, len * 4);
> +	utf8s_to_utf16s(buffer, len * 2, UTF16_LITTLE_ENDIAN, (wchar_t *)(out + 2), len);
>  }

-- 
With Best Regards,
Andy Shevchenko