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ubb-vga2.c: corrected and improved loading of the first TX word

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- ubb-vga2.c (line): write the first word to the TX FIFO after starting
  the command or it is lost
- ubb-vga2.c (line): fetch the first word while waiting for the back
  porch, making sure we have plenty of time for cache effects
- ubb-vga2.c (line): we no longer need to prefetch the first word of
  the next line
This commit is contained in:
Werner Almesberger 2011-04-28 12:30:22 -03:00
parent e94b3bbcfc
commit 4480b32c50
1 changed files with 4 additions and 2 deletions
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6
ubb-vga/ubb-vga2.c
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@ -265,6 +265,7 @@ void setup(void)
static void line(const uint32_t *line) static void line(const uint32_t *line)
{ {
const uint32_t *p = line; const uint32_t *p = line;
uint32_t first;
/* Back porch */ /* Back porch */
@ -273,7 +274,7 @@ static void line(const uint32_t *line)
*msc_strpcl = 1 << 3; /* reset the MSC */ *msc_strpcl = 1 << 3; /* reset the MSC */
// while (*msc_stat & (1 << 15)); // while (*msc_stat & (1 << 15));
*msc_txfifo = *p++; first = *p++;
until(US(0.79)); until(US(0.79));
@ -316,6 +317,8 @@ static void line(const uint32_t *line)
/* Front porch */ /* Front porch */
*msc_txfifo = first;
*pdfuns = CMD; *pdfuns = CMD;
*pddats = HSYNC; *pddats = HSYNC;
*pdfunc = CMD; *pdfunc = CMD;
@ -344,7 +347,6 @@ static void line(const uint32_t *line)
} }
fail: fail:
(void) *(volatile const uint32_t *) p;
until(line_cycles); until(line_cycles);
} }