[ts-7000] Spi driver bug in linux-2.6.27.4-matt-3

["greywolf9923" <>]

There's a bug in the spi_speed_set function:

static int spi_speed_set(struct ep93xx_spi *drv_data, unsigned speed_hz)
{
........
        for (cpsdvr = 2; cpsdvr <= 254; cpsdvr+=2) {
                scr = DIV_ROUND_UP(mainclk_hz / speed_hz, cpsdvr);
                /* now we have SCR+1 in scr, so count with that */
                if (scr == 0) {         /* speed_hz too big */
                        return -EINVAL;
                }
                if (scr <= (255 + 1))
                        break;          /* we have valid scr and cpsdvr */
        }
        if (cpsdvr > 254) { <------BUG HERE
    /* speed_hz is too small, set to minimum speed */
    scr = cpsdvr + 1;
    cpsdvr--;
        }
        scr--;
..........
}

If cpsdvr is greater than 254 will be 256 because of the for
(cpsdvr+=2), so scr will be 257 and cpsdvr 255 out of if, then scr
will finally be 256, but it's not possible because the range for scr
is 0-255 and 2-254 for cpsdvr. I think it'd be better:

        if (cpsdvr == 256) {
               return -EINVAL;
        }

or modify the if:

        if (cpsdvr == 256) {
          /* speed_hz is too small, set to minimum speed */
          scr = 256;
          cpsdvr = 254;
        }
        scr--;


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