linux-kernel - Re: [PATCH 1/3] usb: gadget: storage: Add fsg_get

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Message-ID: <4D7789F2.7000203@nokia.com>
Date:	Wed, 9 Mar 2011 16:08:50 +0200
From:	Roger Quadros <roger.quadros@...ia.com>
To:	ext Sergei Shtylyov <sshtylyov@...sta.com>
CC:	<gregkh@...e.de>, <linux-usb@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] usb: gadget: storage: Add fsg_get_toc helper

Hi,

On 03/09/2011 03:41 PM, ext Sergei Shtylyov wrote:
> Hello.
>
>> --- a/drivers/usb/gadget/storage_common.c
>> +++ b/drivers/usb/gadget/storage_common.c
>> @@ -655,6 +655,85 @@ static void store_cdrom_address(u8 *dest, int msf, u32 addr)
>> }
>> }
>>
>> +/*
>
> The kerneldoc comments should start with "/**".

OK.

>
>> + * put_toc() - Builds a TOC with required format @format.
>
> The function is called gsg_get_toc, isn't it?

Yes :). My initial version was named put_toc(). will correct it.

>
>> + * @curlun: The LUN for which the TOC has to be built
>> + * @msf: Min Sec Frame format or LBA format for address
>> + * @format: TOC format code
>> + * @buf: the buffer into which the TOC is built
>> + *
>> + * Builds a Table of Content which can be used as data for READ_TOC command.
>> + * The TOC simulates a single session, single track CD-ROM mode 1 disc.
>> + *
>> + * Returns number of bytes written to @buf, -EINVAL if format not supported.
>> + */
>> +static int fsg_get_toc(struct fsg_lun *curlun, int msf, int format, u8 *buf)
>> +{
>> + switch (format) {
>> + case 0:
>> + /* Formatted TOC */
>> + memset(buf, 0, 20);
>> + buf[1] = (20-2); /* TOC data length */
>
> Parens not needed here. And kernel style assumes putting spacves around operators.

I copied case 0: code from file_storage.c. But will correct it.
>
>> + buf[2] = 1; /* First track number */
>> + buf[3] = 1; /* Last track number */
>> + buf[5] = 0x16; /* Data track, copying allowed */
>> + buf[6] = 0x01; /* Only track is number 1 */
>> + store_cdrom_address(&buf[8], msf, 0);
>> +
>> + buf[13] = 0x16; /* Lead-out track is data */
>> + buf[14] = 0xAA; /* Lead-out track number */
>> + store_cdrom_address(&buf[16], msf, curlun->num_sectors);
>> + return 20;
>> + break;
>> +
>> + case 2:
>> + /* Raw TOC */
>> + memset(buf, 0, 37); /* Header + A0, A1& A2 descriptors */
>> + buf[1] = 37; /* 4 + 3*11 */
>> + buf[2] = 1; /* First complete session */
>> + buf[3] = 2; /* Last complete session */
>> +
>> + buf += 4;
>> + /* A0 point */
>> + buf[0] = 1; /* Session number */
>> + buf[1] = 0x16; /* Data track, copying alowed */
>> + /* 2 - Track number 0 -> TOC */
>> + buf[3] = 0xA0; /* Point A0 */
>> + /* 4, 5, 6 - Min, sec, frame is zero */
>> + /* 7 - zero */
>> + buf[8] = 1; /* Pmin: 1st track number */
>> + /* 9 - disc type 0: CD-ROM/DA with 1st track in mode 1 */
>> + /* 10 - pframe 0 */
>> +
>> + buf += 11;
>> + /* A1 point*/
>> + buf[0] = 1; /* Session number */
>> + buf[1] = 0x16; /* Data track, copying alowed */
>> + /* 2 - Track number 0 -> TOC */
>> + buf[3] = 0xA1; /* Point A1 */
>> + /* 4, 5, 6 - Min, sec, frame is zero */
>> + /* 7, zero */
>> + buf[8] = 1; /* Pmin: last track number */
>> + /* 9, 10 - pmin and pframe are 0 */
>
> The above code is repetitive -- might be worth factoring out into a function.
>
I would leave it as it is as nobody else would use the function.

> OK, but where this function is called from?
>
from file_storage.c and f_mass_storage.c in the next two patches of this series.

-- 
regards,
-roger
--
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