ALSA: bebob: compare whole string for model name so that readers are not confused

A modalias of 'ieee1394:ven00000D6Cmo00010060sp' hits units for M-Audio
FireWire Audiophile only. However the unit has two states relevant to
loaded firmware. Initial firmware returns 'FW Audiophile Bootloader',
while functional firmware returns 'FW Audiophile'.

ALSA bebob driver compares the units' model name to strings of 24 characters
by the first 15 characters. This is shorter way to differentiate these two
states but confusing to readers.

This commit improves the code for this point. Kernel stack is consumed more in
call of check_audiophile_booted() by a bit.

With initial firmware:
$ ./linux-firewire-utils/src/crpp < /sys/bus/firewire/devices/fw1/config_rom
               ROM header and bus information block
               -----------------------------------------------------------------
400  04276da6  bus_info_length 4, crc_length 39, crc 28070
404  31333934  bus_name "1394"
408  006481f2  irmc 0, cmc 0, isc 0, bmc 0, pmc 0, cyc_clk_acc 100,
               max_rec 8 (512), max_rom 1, gen 15, spd 2 (S400)
40c  000d6c03  company_id 000d6c     |
410  102b7e2e  device_id 03102b7e2e  | EUI-64 000d6c03102b7e2e

               root directory
               -----------------------------------------------------------------
414  00067414  directory_length 6, crc 29716
418  0c0083c0  node capabilities per IEEE 1394
41c  03000d6c  vendor
420  81000009  --> descriptor leaf at 444
424  17010060  model
428  8100000c  --> descriptor leaf at 458
42c  d1000001  --> unit directory at 430

               unit directory at 430
               -----------------------------------------------------------------
430  00049da1  directory_length 4, crc 40353 (should be 48611)
434  1200a02d  specifier id: 1394 TA
438  13014001  version: Vender Unique and AV/C
43c  17010060  model
440  8100000f  --> descriptor leaf at 47c

               descriptor leaf at 444
               -----------------------------------------------------------------
444  0004073e  leaf_length 4, crc 1854
448  00000000  textual descriptor
44c  00000000  minimal ASCII
450  4d2d4155  "M-AU"
454  44494f00  "DIO"

               descriptor leaf at 458
               -----------------------------------------------------------------
458  00086f21  leaf_length 8, crc 28449
45c  00000000  textual descriptor
460  00000000  minimal ASCII
464  46572041  "FW A"
468  7564696f  "udio"
46c  7068696c  "phil"
470  6520426f  "e Bo"
474  6f746c6f  "otlo"
478  61646572  "ader"

               descriptor leaf at 47c
               -----------------------------------------------------------------
47c  00086f21  leaf_length 8, crc 28449
480  00000000  textual descriptor
484  00000000  minimal ASCII
488  46572041  "FW A"
48c  7564696f  "udio"
490  7068696c  "phil"
494  6520426f  "e Bo"
498  6f746c6f  "otlo"
49c  61646572  "ader"

With functional firmware:
$ ./linux-firewire-utils/src/crpp < /sys/bus/firewire/devices/fw1/config_rom
               ROM header and bus information block
               -----------------------------------------------------------------
400  042de16f  bus_info_length 4, crc_length 45, crc 57711
404  31333934  bus_name "1394"
408  f0648122  irmc 1, cmc 1, isc 1, bmc 1, pmc 0, cyc_clk_acc 100,
               max_rec 8 (512), max_rom 1, gen 2, spd 2 (S400)
40c  000d6c03  company_id 000d6c     |
410  002b7e2e  device_id 03002b7e2e  | EUI-64 000d6c03002b7e2e

               root directory
               -----------------------------------------------------------------
414  0009dac4  directory_length 9, crc 56004
418  0400000d  hardware version
41c  0c0083c0  node capabilities per IEEE 1394
420  03000d6c  vendor
424  81000012  --> descriptor leaf at 46c
428  17010060  model
42c  81000015  --> descriptor leaf at 480
430  13ffffff  version
434  d1000002  --> unit directory at 43c
438  d4000006  --> dependent info directory at 450

               unit directory at 43c
               -----------------------------------------------------------------
43c  00041eb9  directory_length 4, crc 7865
440  1200a02d  specifier id: 1394 TA
444  13014001  version: Vender Unique and AV/C
448  17010060  model
44c  81000014  --> descriptor leaf at 49c

               dependent info directory at 450
               -----------------------------------------------------------------
450  000637c7  directory_length 6, crc 14279
454  120007f5  specifier id
458  13000001  version
45c  3affffc7  (immediate value)
460  3b100000  (immediate value)
464  3cffffc7  (immediate value)
468  3d600000  (immediate value)

               descriptor leaf at 46c
               -----------------------------------------------------------------
46c  0004b8e4  leaf_length 4, crc 47332
470  00000000  textual descriptor
474  00000000  minimal ASCII
478  4d2d4175  "M-Au"
47c  64696f00  "dio"

               descriptor leaf at 480
               -----------------------------------------------------------------
480  0006194b  leaf_length 6, crc 6475
484  00000000  textual descriptor
488  00000000  minimal ASCII
48c  46572041  "FW A"
490  7564696f  "udio"
494  7068696c  "phil"
498  65000000  "e"

               descriptor leaf at 49c
               -----------------------------------------------------------------
49c  0006194b  leaf_length 6, crc 6475
4a0  00000000  textual descriptor
4a4  00000000  minimal ASCII
4a8  46572041  "FW A"
4ac  7564696f  "udio"
4b0  7068696c  "phil"
4b4  65000000  "e"
Reported-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Reported-by: Joe Perches <joe@perches.com>
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/firewire/bebob/bebob.c

@@ -172,12 +172,12 @@ get_saffire_spec(struct fw_unit *unit)
 static bool
 check_audiophile_booted(struct fw_unit *unit)
 {
-	char name[24] = {0};
+	char name[28] = {0};
 
 	if (fw_csr_string(unit->directory, CSR_MODEL, name, sizeof(name)) < 0)
 		return false;
 
-	return strncmp(name, "FW Audiophile Bootloader", 15) != 0;
+	return strncmp(name, "FW Audiophile Bootloader", 24) != 0;
 }
 
 static void