From 69433ff94c7890e4e2a0f8df746a846d8158ad97 Mon Sep 17 00:00:00 2001
From: Martin Guy <martinwguy@gmail.com>
Date: Wed, 13 Jul 2011 18:53:18 +0200
Subject: [PATCH] Fix MMCFS timeout code to wait for >= the required timeout

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.
---
 src/elua_mmc.c | 27 +++++++++++++++++++++++----
 1 file changed, 23 insertions(+), 4 deletions(-)

diff --git a/src/elua_mmc.c b/src/elua_mmc.c
index f62939ce..2208682a 100644
--- a/src/elua_mmc.c
+++ b/src/elua_mmc.c
@@ -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 )