Re: [PATCH 1/4] media: dvb/af9015, implement eeprom hashing

From: Antti Palosaari
Date: Sun Jan 24 2010 - 11:16:43 EST


Hei,
Comments below.

On 01/22/2010 05:10 PM, Jiri Slaby wrote:
We read the eeprom anyway for dumping. Switch the dumping to
print_hex_dump_bytes and compute hash above that by
hash = 0;
for (u32 VAL) in (eeprom):
hash *= GOLDEN_RATIO_PRIME_32
hash += VAL; // while preserving endinaness

The computation is moved earlier to the flow, namely from
af9015_af9013_frontend_attach to af9015_read_config, so that
we can access the sum in af9015_read_config already.

Signed-off-by: Jiri Slaby<jslaby@xxxxxxx>
Cc: Antti Palosaari<crope@xxxxxx>
Cc: Mauro Carvalho Chehab<mchehab@xxxxxxxxxx>
Cc: linux-media@xxxxxxxxxxxxxxx
---
drivers/media/dvb/dvb-usb/af9015.c | 65 +++++++++++++++++++++++------------
drivers/media/dvb/dvb-usb/af9015.h | 1 +
2 files changed, 44 insertions(+), 22 deletions(-)

diff --git a/drivers/media/dvb/dvb-usb/af9015.c b/drivers/media/dvb/dvb-usb/af9015.c
index a365c05..616b3ba 100644
--- a/drivers/media/dvb/dvb-usb/af9015.c
+++ b/drivers/media/dvb/dvb-usb/af9015.c
@@ -21,6 +21,8 @@
*
*/

+#include<linux/hash.h>
+
#include "af9015.h"
#include "af9013.h"
#include "mt2060.h"
@@ -553,26 +555,45 @@ exit:
return ret;
}

-/* dump eeprom */
-static int af9015_eeprom_dump(struct dvb_usb_device *d)
+/* hash (and dump) eeprom */
+static int af9015_eeprom_hash(struct usb_device *udev)
{
- u8 reg, val;
+ static const unsigned int eeprom_size = 256;
+ unsigned int reg;
+ int ret;
+ u8 val, *eeprom;
+ struct req_t req = {READ_I2C, AF9015_I2C_EEPROM, 0, 0, 1, 1,&val};

- for (reg = 0; ; reg++) {
- if (reg % 16 == 0) {
- if (reg)
- deb_info(KERN_CONT "\n");
- deb_info(KERN_DEBUG "%02x:", reg);
- }
- if (af9015_read_reg_i2c(d, AF9015_I2C_EEPROM, reg,&val) == 0)
- deb_info(KERN_CONT " %02x", val);
- else
- deb_info(KERN_CONT " --");
- if (reg == 0xff)
- break;
+ eeprom = kmalloc(eeprom_size, GFP_KERNEL);
+ if (eeprom == NULL)
+ return -ENOMEM;
+
+ for (reg = 0; reg< eeprom_size; reg++) {
+ req.addr = reg;
+ ret = af9015_rw_udev(udev,&req);
+ if (ret)
+ goto free;
+ eeprom[reg] = val;
}
- deb_info(KERN_CONT "\n");
- return 0;
+
+ if (dvb_usb_af9015_debug& 0x01)
+ print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, eeprom,
+ eeprom_size);
+
+ BUG_ON(eeprom_size % 4);
+
+ af9015_config.eeprom_sum = 0;
+ for (reg = 0; reg< eeprom_size / sizeof(u32); reg++) {
+ af9015_config.eeprom_sum *= GOLDEN_RATIO_PRIME_32;
+ af9015_config.eeprom_sum += le32_to_cpu(((u32 *)eeprom)[reg]);
+ }
+
+ deb_info("%s: eeprom sum=%.8x\n", __func__, af9015_config.eeprom_sum);

Does this sum contain all 256 bytes from EEPROM? 256/4 is 64.

regards
Antti
--
http://palosaari.fi/
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/