diff options
| author | Dan Carpenter <[email protected]> | 2020-01-31 07:57:39 +0300 |
|---|---|---|
| committer | Alex Deucher <[email protected]> | 2020-03-13 11:52:35 -0400 |
| commit | 9543a9c3e2359db4b9576ee2ae3bae5a28e08387 (patch) | |
| tree | 04b4d01fa15a3339bec2a81b4e41fcf5603dc02f | |
| parent | 95f247e73f8dd4d3f586b410d07df791ca3b2fef (diff) | |
drm/amd/display: Possible divide by zero in set_speed()
If "speed" is zero then we use it as a divisor to find "prescale". It's
better to move the check for zero to the very start of the function.
Fixes: 9eeec26a1339 ("drm/amd/display: Refine i2c frequency calculating sequence")
Signed-off-by: Dan Carpenter <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>
| -rw-r--r-- | drivers/gpu/drm/amd/display/dc/dce/dce_i2c_hw.c | 23 |
1 files changed, 12 insertions, 11 deletions
diff --git a/drivers/gpu/drm/amd/display/dc/dce/dce_i2c_hw.c b/drivers/gpu/drm/amd/display/dc/dce/dce_i2c_hw.c index 066188ba7949..24adec407972 100644 --- a/drivers/gpu/drm/amd/display/dc/dce/dce_i2c_hw.c +++ b/drivers/gpu/drm/amd/display/dc/dce/dce_i2c_hw.c @@ -267,6 +267,9 @@ static void set_speed( uint32_t xtal_ref_div = 0; uint32_t prescale = 0; + if (speed == 0) + return; + REG_GET(MICROSECOND_TIME_BASE_DIV, XTAL_REF_DIV, &xtal_ref_div); if (xtal_ref_div == 0) @@ -274,17 +277,15 @@ static void set_speed( prescale = ((dce_i2c_hw->reference_frequency * 2) / xtal_ref_div) / speed; - if (speed) { - if (dce_i2c_hw->masks->DC_I2C_DDC1_START_STOP_TIMING_CNTL) - REG_UPDATE_N(SPEED, 3, - FN(DC_I2C_DDC1_SPEED, DC_I2C_DDC1_PRESCALE), prescale, - FN(DC_I2C_DDC1_SPEED, DC_I2C_DDC1_THRESHOLD), 2, - FN(DC_I2C_DDC1_SPEED, DC_I2C_DDC1_START_STOP_TIMING_CNTL), speed > 50 ? 2:1); - else - REG_UPDATE_N(SPEED, 2, - FN(DC_I2C_DDC1_SPEED, DC_I2C_DDC1_PRESCALE), prescale, - FN(DC_I2C_DDC1_SPEED, DC_I2C_DDC1_THRESHOLD), 2); - } + if (dce_i2c_hw->masks->DC_I2C_DDC1_START_STOP_TIMING_CNTL) + REG_UPDATE_N(SPEED, 3, + FN(DC_I2C_DDC1_SPEED, DC_I2C_DDC1_PRESCALE), prescale, + FN(DC_I2C_DDC1_SPEED, DC_I2C_DDC1_THRESHOLD), 2, + FN(DC_I2C_DDC1_SPEED, DC_I2C_DDC1_START_STOP_TIMING_CNTL), speed > 50 ? 2:1); + else + REG_UPDATE_N(SPEED, 2, + FN(DC_I2C_DDC1_SPEED, DC_I2C_DDC1_PRESCALE), prescale, + FN(DC_I2C_DDC1_SPEED, DC_I2C_DDC1_THRESHOLD), 2); } static bool setup_engine( |