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git://projects.qi-hardware.com/ben-blinkenlights.git
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ubb-la/ubb-la.c: raise MMC bus clock to 84 MHz during overhead
We also de-optimize the start bit (DAT0=0) phase for now. In the 12 MHz scenario, this produces the following results: 1 3 gap+0 2 0 1 3 ------- ------- ------- ------- ------- ------- ------- 8 38 26 100 146 102 38 26 6 52 39 26 55 147 41 26 105 97 39 26 10 146 Note that the gap now includes the start bit phase, since the clock change may complicate the calculation of how many 12 MHz samples it corresponds to.
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@ -167,7 +167,8 @@ quit:
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}
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static void xfers(unsigned long *bufs, int n_bufs, int nibbles)
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static void xfers(unsigned long *bufs, int n_bufs, int nibbles,
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const struct mmcclk *clk, const struct mmcclk *fast_clk)
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{
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int i = 0;
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@ -194,18 +195,24 @@ static void xfers(unsigned long *bufs, int n_bufs, int nibbles)
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MSC_STRPCL = MSC_STRPCRL_START_OP;
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MSC_CLKRT = fast_clk->clkrt;
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MSCCDR = 0;
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/*
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* Experimental value for 12 MSa/s: hangs always/usually with
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* 231 cycles, hangs sometimes with 232, hands never (so far)
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* with 233.
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*/
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for (j = 0; j != 233; j++) asm volatile ("");
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// for (j = 0; j != 233; j++) asm volatile ("");
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// while (MSC_STAT & MSC_STAT_DATA_FIFO_EMPTY);
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// while (!(MSC_STAT & MSC_STAT_END_CMD_RES));
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while (!(MSC_STAT & MSC_STAT_END_CMD_RES));
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IN(UBB_CMD);
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MSCCDR = clk->clkdiv;
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MSC_CLKRT = clk->clkrt;
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DCS(DMA) =
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DCS_NDES | /* no descriptor */
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DCS_CTE; /* enable channel */
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@ -291,7 +298,8 @@ static int do_buf(int nibbles, uint32_t trigger, uint32_t mask)
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}
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static void do_bufs(int n_bufs, int nibbles)
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static void do_bufs(int n_bufs, int nibbles,
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const struct mmcclk *clk, const struct mmcclk *fast_clk)
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{
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uint8_t *bufs[n_bufs];
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struct physmem_vec vecs[n_bufs];
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@ -316,7 +324,8 @@ static void do_bufs(int n_bufs, int nibbles)
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}
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addrs[i] = vecs[i].addr;
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}
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xfers(addrs, n_bufs, nibbles);
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assert(!fast_clk->clkdiv);
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xfers(addrs, n_bufs, nibbles, clk, fast_clk);
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for (i = 0; i != n_bufs; i++)
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print_samples(stdout, bufs[i], 0, nibbles);
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@ -382,7 +391,7 @@ int main(int argc, char **argv)
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unsigned long trigger = 1, mask = 0;
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unsigned long multi = 0;
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int clkout = 0;
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struct mmcclk clk;
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struct mmcclk clk, fast_clk;
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char *end;
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int c, res;
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@ -442,7 +451,8 @@ int main(int argc, char **argv)
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if (!multi) {
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res = !do_buf(8128, trigger, mask);
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} else {
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do_bufs(multi, 8128);
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frequency(&fast_clk, 84e6, 1);
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do_bufs(multi, 8128, &clk, &fast_clk);
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res = 0;
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}
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