drm/bridge: analogix_dp: some rockchip chips need to flip REF_CLK bit setting

As vendor document indicate, when REF_CLK bit set 0, then DP
phy's REF_CLK should switch to 24M source clock.

But due to IC PHY layout mistaken, some chips need to flip this
bit(like RK3288), and unfortunately they didn't indicate in the
DP version register. That's why we have to make this little hack.

Signed-off-by: Yakir Yang <ykk@rock-chips.com>
Reviewed-by: Tomasz Figa <tomasz.figa@chromium.com>
Tested-by: Javier Martinez Canillas <javier@osg.samsung.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>

drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c

@@ -74,8 +74,12 @@ void analogix_dp_init_analog_param(struct analogix_dp_device *dp)
 	reg = SEL_24M | TX_DVDD_BIT_1_0625V;
 	writel(reg, dp->reg_base + ANALOGIX_DP_ANALOG_CTL_2);
 
-	if (dp->plat_data && (dp->plat_data->dev_type == RK3288_DP)) {
-		writel(REF_CLK_24M, dp->reg_base + ANALOGIX_DP_PLL_REG_1);
+	if (dp->plat_data && is_rockchip(dp->plat_data->dev_type)) {
+		reg = REF_CLK_24M;
+		if (dp->plat_data->dev_type == RK3288_DP)
+			reg ^= REF_CLK_MASK;
+
+		writel(reg, dp->reg_base + ANALOGIX_DP_PLL_REG_1);
 		writel(0x95, dp->reg_base + ANALOGIX_DP_PLL_REG_2);
 		writel(0x40, dp->reg_base + ANALOGIX_DP_PLL_REG_3);
 		writel(0x58, dp->reg_base + ANALOGIX_DP_PLL_REG_4);
@@ -244,7 +248,7 @@ void analogix_dp_set_analog_power_down(struct analogix_dp_device *dp,
 	u32 reg;
 	u32 phy_pd_addr = ANALOGIX_DP_PHY_PD;
 
-	if (dp->plat_data && (dp->plat_data->dev_type == RK3288_DP))
+	if (dp->plat_data && is_rockchip(dp->plat_data->dev_type))
 		phy_pd_addr = ANALOGIX_DP_PD;
 
 	switch (block) {
@@ -448,7 +452,7 @@ void analogix_dp_init_aux(struct analogix_dp_device *dp)
 	analogix_dp_reset_aux(dp);
 
 	/* Disable AUX transaction H/W retry */
-	if (dp->plat_data && (dp->plat_data->dev_type == RK3288_DP))
+	if (dp->plat_data && is_rockchip(dp->plat_data->dev_type))
 		reg = AUX_BIT_PERIOD_EXPECTED_DELAY(0) |
 		      AUX_HW_RETRY_COUNT_SEL(3) |
 		      AUX_HW_RETRY_INTERVAL_600_MICROSECONDS;

drivers/gpu/drm/bridge/analogix/analogix_dp_reg.h

@@ -165,6 +165,7 @@
 /* ANALOGIX_DP_PLL_REG_1 */
 #define REF_CLK_24M				(0x1 << 0)
 #define REF_CLK_27M				(0x0 << 0)
+#define REF_CLK_MASK				(0x1 << 0)
 
 /* ANALOGIX_DP_LANE_MAP */
 #define LANE3_MAP_LOGIC_LANE_0			(0x0 << 6)

include/drm/bridge/analogix_dp.h

@@ -18,6 +18,11 @@ enum analogix_dp_devtype {
 	RK3288_DP,
 };
 
+static inline bool is_rockchip(enum analogix_dp_devtype type)
+{
+	return type == RK3288_DP;
+}
+
 struct analogix_dp_plat_data {
 	enum analogix_dp_devtype dev_type;
 	struct drm_panel *panel;