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Fix MMCFS timeout code to wait for >= the required timeout

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MMCFS timeouts work by counting ticks of the virtual timer, which is
free-running and could tick immediately, giving a zero timeout.
This fixes the calculation of the number of ticks to wait for to set up
an N-millisecond timeout, ensuring that the actual timeout used is >= N.
This commit is contained in:
Martin Guy 2011-07-13 18:53:18 +02:00
parent 5cb72c0595
commit 69433ff94c
1 changed files with 23 additions and 4 deletions
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27
src/elua_mmc.c
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@ -67,6 +67,25 @@ BYTE CardType; /* b0:MMC, b1:SDC, b2:Block addressing */
static
BYTE PowerFlag = 0; /* indicates if "power" is on */
/*-----------------------------------------------------------------------*/
/* Find the value to set in Timer1 or Timer2 to obtain a timeout of at */
/* least N milliseconds. */
/* */
/* Timer1 and Timer2 are decremented by the virtual timer interrupt, */
/* which is free-running and will sometimes decrement TimerN immediately */
/* so to wait for N ms to pass, you need to wait for N+1 ticks to occur. */
/* */
/* Usage example: */
/* Timer1 = set_Timer_ms(N); */
/* do { whatever } while (Timer1); */
/*-----------------------------------------------------------------------*/
static UINT set_Timer_ms(UINT ms)
{
UINT ticks = ms / MMCFS_TICK_MS;
return (ticks > 0 ? ticks : 1) + 1;
}
/*-----------------------------------------------------------------------*/
/* Transmit a byte to MMC via SPI (Platform dependent) */
/*-----------------------------------------------------------------------*/
@ -109,7 +128,7 @@ BYTE wait_ready (void)
{
BYTE res;
Timer2 = 500/MMCFS_TICK_MS; /* Wait for ready in timeout of 500ms */
Timer2 = set_Timer_ms(500); /* Wait for ready in timeout of 500ms. */
rcvr_spi();
do
res = rcvr_spi();
@ -205,8 +224,7 @@ BOOL rcvr_datablock (
{
BYTE token;
Timer1 = 100/MMCFS_TICK_MS ? 100/MMCFS_TICK_MS : 1;
Timer1 = set_Timer_ms(100);
do { /* Wait for data packet in timeout of 100ms */
token = rcvr_spi();
} while ((token == 0xFF) && Timer1);
@ -326,7 +344,7 @@ DSTATUS disk_initialize (
SELECT(); /* CS = L */
ty = 0;
if (send_cmd(CMD0, 0) == 1) { /* Enter Idle state */
Timer1 = 1000/MMCFS_TICK_MS; /* Initialization timeout of 1000 msec */
Timer1 = set_Timer_ms(1000); /* Initialization timeout of 1000 msec */
if (send_cmd(CMD8, 0x1AA) == 1) { /* SDC Ver2+ */
for (n = 0; n < 4; n++) ocr[n] = rcvr_spi();
if (ocr[2] == 0x01 && ocr[3] == 0xAA) { /* The card can work at vdd range of 2.7-3.6V */
@ -583,6 +601,7 @@ DRESULT disk_ioctl (
/*-----------------------------------------------------------------------*/
/* Device Timer Interrupt Procedure (Platform dependent) */
/*-----------------------------------------------------------------------*/
/* This function must be called in period of 10ms */
void disk_timerproc( void )