Problem with sh4 7760 on logic PD lsh-7760-10 card

Hi All,
I tried to run linux 2.6.8.1 and the CVS linux-sh tree on lsh-7760-10 card.
I compiled sh-ipl+g for running together the native ipl of the board and wirks 
properly.
I found that the code arch/sh/kernel/cpu/sh4/probe.c
at line 100
        case 0x500 ... 0x501:
                switch (prr) {
                    case 0x10: cpu_data->type = CPU_SH7750R; break;
                    case 0x11: cpu_data->type = CPU_SH7751R; break;
                    case 0x50: cpu_data->type = CPU_SH7760;  break;
                }

doesn't work because of prr is shifted of 4 bits and on the sh 7760 hw manual 
I read the MSB of the first byte is not defined so that it not sure 0x50 is 
really 0x50 but is could be 0x5x (x in [0,...,f]).
In fact I added by test:
                switch ((prr  >>  4) & 0x0f) {
                    case 0x05: cpu_data->type = CPU_SH7760;  break;
                }


and I could boot the kernel successfully.

Why could be such a problem? Is it a bug or am I misundrestandig anything?
If it is a bug, how ca I solve propely it? Shoud I have to add a

#ifdef CONFIG_myboard

#endif

Let me know.

Fabio


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