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mips: mt76x8: ddr_cal: Correct dqs_find_min/max implementations 

The current implementations have some issues detecting the correct
values:

dqs_find_max() will return "last passing fieldval + 1" instead of
"last passing fieldval". Also it will return "maxval + 1" in the
case that all fieldvals are tested valid (without error).

dqs_find_min() will not test the "lowest" value because of using ">"
instead of ">=".

This patch now rewrites these functions to fix those issues. Also,
this patch uses the same approach of a for loop in both functions making
it easier to read and maintain.

Since the variables are integers now, we can use min()/max(), which
handles the wrap around case for fieldval=0: return (0 - 1).

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Weijie Gao <weijie.gao@mediatek.com>
Cc: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Reviewed-by: Weijie Gao <weijie.gao@mediatek.com>
This commit is contained in:
Stefan Roese 2020-03-06 15:14:05 +01:00 committed by Daniel Schwierzeck
parent 112add362b
commit 04d21a93fa
1 changed files with 10 additions and 18 deletions
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28
arch/mips/mach-mtmips/ddr_cal.c
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@ -74,39 +74,31 @@ static inline bool dqs_test_error(void __iomem *memc, u32 memsize, u32 dqsval,
static inline int dqs_find_max(void __iomem *memc, u32 memsize, int initval,
int maxval, int shift, u32 regval)
{
int fieldval = initval;
int fieldval;
u32 dqsval;
do {
for (fieldval = initval; fieldval <= maxval; fieldval++) {
dqsval = regval | (fieldval << shift);
if (dqs_test_error(memc, memsize, dqsval, 3))
break;
return max(fieldval - 1, initval);
}
fieldval++;
} while (fieldval <= maxval);
return fieldval;
return maxval;
}
static inline int dqs_find_min(void __iomem *memc, u32 memsize, int initval,
int minval, int shift, u32 regval)
{
int fieldval = initval;
int fieldval;
u32 dqsval;
while (fieldval > minval) {
for (fieldval = initval; fieldval >= minval; fieldval--) {
dqsval = regval | (fieldval << shift);
if (dqs_test_error(memc, memsize, dqsval, 1)) {
fieldval++;
break;
}
fieldval--;
if (dqs_test_error(memc, memsize, dqsval, 1))
return min(fieldval + 1, initval);
}
return fieldval;
return minval;
}
void ddr_calibrate(void __iomem *memc, u32 memsize, u32 bw)