On 23.07.2014 11:20, Antti Palosaari wrote: > Moikka Matthias > Moikka Antti, > On 07/22/2014 11:12 PM, Matthias Schwarzott wrote: >> + >> + my $CRC="\x0A\xCC"; >> + my $BLOCKS_MAIN="\x27"; >> + open FW,">$fwfile"; >> + print FW "\x01\x00"; # just a version id for the driver itself >> + print FW "\x9A"; # fw version >> + print FW "\x00"; # padding >> + print FW "$BLOCKS_MAIN"; # number of blocks of main part >> + print FW "\x00"; # padding >> + print FW "$CRC"; # 16bit crc value of main part >> + appendfile(FW,"$tmpdir/fw1"); > > I have to say I little bit dislike that kind of own headers. There is no > way to read firmware version from binary itself (very often there is)? > Whats is benefit of telling how many blocks there is? Isn't it possible > to detect somehow by examining firmware image itself runtime? > > Anyhow, you are the author of that driver and even I don't personally > like those, I think it is up to your decision as a author. > I thought a bit about the need for the header. And yes, some fields I can get rid of. firmware version: I guess that the exact version number is not really needed - it is just written to a seperate register - and later only read to check if firmware was already downloaded (but for documentation it might be interesting). I have no clue where it could be in the raw block - it looks like it is writing to just some memory addresses. But for the pure process it would also work to write a random number != 0x00. For $BLOCKS_MAIN: The firmware is downloaded like this: * write 1 block * reset crc logic * write $BLOCKS_MAIN * read out crc and compare against $CRC in header * write last 5 blocks so the number of blocks in $BLOCKS_MAIN could be checked by iterating over all blocks counting them and then substracting 6. The crc value: It protects the content of the file until it is in the demod - so calculating it on my own would only check if the data is correctly transferred from the driver into the chip. But for this I needed to know the algorithm and which data is checksummed exactly. Are the different algorithms for CRC values that give 16 bit of output? Matthias -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
