w1_therm:Retries:remove old code add CRC

w1_therm includes some obsolete code to detect bad_roms, this is no longer relevant.
The retry code is only used for this bad_rom test, however there is a CRC check that detects a bad read, but does not trigger a retry. This patch removes all the bad_rom code and uses the CRC check to trigger retries.

Patch is against Raspberry 3.2.27 ( my test hardware) but has also been tested against 3.7.

David Stevenson david at avoncliff.com

index 016dd7d..8166075 100644
@@ -45,10 +45,6 @@ MODULE_DESCRIPTION("Driver for 1-wire Dallas network

protocol, temperature famil
static int w1_strong_pullup = 1; module_param_named(strong_pullup, w1_strong_pullup, int, 0);

-static u8 bad_roms[][9] = {
- {0xaa, 0x00, 0x4b, 0x46, 0xff, 0xff, 0x0c, 0x10, 0x87},
- {}
- };

static ssize_t w1_therm_read(struct device *device,
struct device_attribute *attr, char *buf);
@@ -159,16 +155,6 @@ static inline int w1_convert_temp(u8 rom[9], u8 fid)
return 0;
}

-static int w1_therm_check_rom(u8 rom[9])
-{
- int i;
-
- for (i=0; i<sizeof(bad_roms)/9; ++i)
- if (!memcmp(bad_roms[i], rom, 9))
- return 1;
-
- return 0;
-}

static ssize_t w1_therm_read(struct device *device,
struct device_attribute *attr, char *buf)
@@ -183,10 +169,11 @@ static ssize_t w1_therm_read(struct device *device,

memset(rom, 0, sizeof(rom));

- verdict = 0;
- crc = 0;
-
while (max_trying--) {
+
+ verdict = 0;
+ crc = 0;
+
if (!w1_reset_select_slave(sl)) {
int count = 0;
unsigned int tm = 750;
@@ -214,7 +201,7 @@ static ssize_t w1_therm_read(struct device *device,
}
}

- if (!w1_therm_check_rom(rom))
+ if (verdict)
break;
}