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Return to using disable/enable_intr() for guarding DMA register access.

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Mask the read value from the count register in order to return zero correctly
after TC, as per intel datasheet : "If it is not autoinitialised, this
register will have a count of FFFFH after TC"
This commit is contained in:
msmith 1997-07-29 05:24:36 +00:00
parent b1debf973d
commit 481c991667
2 changed files with 20 additions and 14 deletions
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17
sys/amd64/isa/isa.c
View File

@ -34,7 +34,7 @@
* SUCH DAMAGE.
*
* from: @(#)isa.c 7.2 (Berkeley) 5/13/91
* $Id: isa.c,v 1.97 1997/07/28 07:49:40 msmith Exp $
* $Id: isa.c,v 1.98 1997/07/28 09:13:11 msmith Exp $
*/
/*
@ -928,21 +928,24 @@ isa_dmastatus(int chan)
waport = DMA2_CHN(chan - 4) + 2;
}
ef = read_eflags(); /* get current flags */
disable_intr(); /* no interrupts Mr Jones! */
outb(ffport, 0); /* clear register LSB flipflop */
low1 = inb(waport);
high1 = inb(waport);
outb(ffport, 0); /* clear again (paranoia?) */
outb(ffport, 0); /* clear again */
low2 = inb(waport);
high2 = inb(waport);
write_eflags(ef); /* restore flags */
enable_intr(); /* enable interrupts again */
/* now decide if a wrap has tried to skew our results */
/*
* Now decide if a wrap has tried to skew our results.
* Note that after TC, the count will read 0xffff, while we want
* to return zero, so we add and then mask to compensate.
*/
if (low1 >= low2) {
cnt = low1 + (high1 << 8) + 1;
cnt = (low1 + (high1 << 8) + 1) & 0xffff;
} else {
cnt = low2 + (high2 << 8) + 1;
cnt = (low2 + (high2 << 8) + 1) & 0xffff;
}
if (chan >= 4) /* high channels move words */

17
sys/i386/isa/isa.c
View File

@ -34,7 +34,7 @@
* SUCH DAMAGE.
*
* from: @(#)isa.c 7.2 (Berkeley) 5/13/91
* $Id: isa.c,v 1.97 1997/07/28 07:49:40 msmith Exp $
* $Id: isa.c,v 1.98 1997/07/28 09:13:11 msmith Exp $
*/
/*
@ -928,21 +928,24 @@ isa_dmastatus(int chan)
waport = DMA2_CHN(chan - 4) + 2;
}
ef = read_eflags(); /* get current flags */
disable_intr(); /* no interrupts Mr Jones! */
outb(ffport, 0); /* clear register LSB flipflop */
low1 = inb(waport);
high1 = inb(waport);
outb(ffport, 0); /* clear again (paranoia?) */
outb(ffport, 0); /* clear again */
low2 = inb(waport);
high2 = inb(waport);
write_eflags(ef); /* restore flags */
enable_intr(); /* enable interrupts again */
/* now decide if a wrap has tried to skew our results */
/*
* Now decide if a wrap has tried to skew our results.
* Note that after TC, the count will read 0xffff, while we want
* to return zero, so we add and then mask to compensate.
*/
if (low1 >= low2) {
cnt = low1 + (high1 << 8) + 1;
cnt = (low1 + (high1 << 8) + 1) & 0xffff;
} else {
cnt = low2 + (high2 << 8) + 1;
cnt = (low2 + (high2 << 8) + 1) & 0xffff;
}
if (chan >= 4) /* high channels move words */