Laurent,
now things are getting clearer. All this sounds to me that the shift direction in slave serial mode is not compatible to the parallel download code. When we say that fpga_load (and the fpga load command) should only work for promgen files with mirrored bits and fpga_loadbitstream() (and the fpga loadb command) should be used for .bit files, I would like to get rid of the mirroring at least for slave serial mode because changing the shift order is much more efficient.
Bruce suggested a CONFIG option to turn on/off mirroring. This is not the right way. It should be handled by the FPGA subsystem. What about passing a bitorder flag down to the load functions? So we get rid of the huge malloc in loadbitstream and we can just swap bits in parallel mode just before writing it to the FPGA port. For Slave serial mode the _load funtion can use the correct shift direction and so swapping is needed.
Matthias
On Tuesday 21 August 2007 10:59, Laurent Pinchart wrote:
So what option are you using for and which bitsteam format/file are you using?
I'm calling fpga_load directly from board-specific code, using PROMgen generated data (with bit mirroring applied).
Bit mirroring might not be needed in slave serial mode, but is needed in slave parallel mode. Bytes in the .bit file are stored with the LSB on the left side. The bytes must then be reversed before being written in slave parallel mode, as the FPGA expects the LSB on D0, not on D7.
In slave serial mode, you can choose the shift direction, so mirroring is not required.
I still vote for removing the bit mirror :-)
Without mirroring, bitstreams won't load in slave parallel mode. You should keep mirroring, and change the slave serial code to shift bits the other way around.
Are you using .bit Images, PROM files and which fpga command option do you use? load or loadb?
I don't use the fpga commands, but call fpga_load() directly from board specific code. This is roughly equivalent to "fpga load". The data come from a bit-mirrored PROM file. I used to use a .bit file, which required "fpga loadb" to be loaded correctly.