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-rw-r--r--drivers/gpu/drm/radeon/radeon_i2c.c17
1 files changed, 8 insertions, 9 deletions
diff --git a/drivers/gpu/drm/radeon/radeon_i2c.c b/drivers/gpu/drm/radeon/radeon_i2c.c
index 5d93418f9fca..f007fcb1191b 100644
--- a/drivers/gpu/drm/radeon/radeon_i2c.c
+++ b/drivers/gpu/drm/radeon/radeon_i2c.c
@@ -183,11 +183,10 @@ static void set_data(void *i2c_priv, int data)
static u32 radeon_get_i2c_prescale(struct radeon_device *rdev)
{
- struct radeon_pll *spll = &rdev->clock.spll;
u32 sclk = radeon_get_engine_clock(rdev);
u32 prescale = 0;
- u32 n, m;
- u8 loop;
+ u32 nm;
+ u8 n, m, loop;
int i2c_clock;
switch (rdev->family) {
@@ -203,13 +202,15 @@ static u32 radeon_get_i2c_prescale(struct radeon_device *rdev)
case CHIP_R300:
case CHIP_R350:
case CHIP_RV350:
- n = (spll->reference_freq) / (4 * 6);
+ i2c_clock = 60;
+ nm = (sclk * 10) / (i2c_clock * 4);
for (loop = 1; loop < 255; loop++) {
- if ((loop * (loop - 1)) > n)
+ if ((nm / loop) < loop)
break;
}
- m = loop - 1;
- prescale = m | (loop << 8);
+ n = loop - 1;
+ m = loop - 2;
+ prescale = m | (n << 8);
break;
case CHIP_RV380:
case CHIP_RS400:
@@ -217,7 +218,6 @@ static u32 radeon_get_i2c_prescale(struct radeon_device *rdev)
case CHIP_R420:
case CHIP_R423:
case CHIP_RV410:
- sclk = radeon_get_engine_clock(rdev);
prescale = (((sclk * 10)/(4 * 128 * 100) + 1) << 8) + 128;
break;
case CHIP_RS600:
@@ -232,7 +232,6 @@ static u32 radeon_get_i2c_prescale(struct radeon_device *rdev)
case CHIP_RV570:
case CHIP_R580:
i2c_clock = 50;
- sclk = radeon_get_engine_clock(rdev);
if (rdev->family == CHIP_R520)
prescale = (127 << 8) + ((sclk * 10) / (4 * 127 * i2c_clock));
else
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