drm/amd/display: Possible divide by zero in set_speed() (9543a9c3) · Commits · 戴 / test

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: ("drm/amd/display: Refine i2c frequency calculating sequence") Signed-off-by:

Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by:

Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dce/dce_i2c_hw.c

+12 −11

Original line number	Diff line number	Diff line
		@@ -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)
		@@ -274,7 +277,6 @@ 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,
		@@ -285,7 +287,6 @@ static void set_speed(
		FN(DC_I2C_DDC1_SPEED, DC_I2C_DDC1_PRESCALE), prescale,
		FN(DC_I2C_DDC1_SPEED, DC_I2C_DDC1_THRESHOLD), 2);
		}
		}

		static bool setup_engine(
		struct dce_i2c_hw *dce_i2c_hw)

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