drm/bridge: anx7625: Set HPD irq detect window to 2ms

Some panels trigger HPD irq due to noise, the HPD debounce
may be 1.8ms, exceeding the default irq detect window, ~1.4ms.
This patch set HPD irq detection window to 2ms to
tolerate the HPD noise.
Signed-off-by: Xin Ji <xji@analogixsemi.com>
Reviewed-by: Robert Foss <robert.foss@linaro.org>
Signed-off-by: Robert Foss <robert.foss@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220903130833.541463-1-xji@analogixsemi.com

drivers/gpu/drm/bridge/analogix/anx7625.c

@@ -1440,6 +1440,20 @@ static void anx7625_start_dp_work(struct anx7625_data *ctx)
 
 static int anx7625_read_hpd_status_p0(struct anx7625_data *ctx)
 {
+	int ret;
+
+	/* Set irq detect window to 2ms */
+	ret = anx7625_reg_write(ctx, ctx->i2c.tx_p2_client,
+				HPD_DET_TIMER_BIT0_7, HPD_TIME & 0xFF);
+	ret |= anx7625_reg_write(ctx, ctx->i2c.tx_p2_client,
+				 HPD_DET_TIMER_BIT8_15,
+				 (HPD_TIME >> 8) & 0xFF);
+	ret |= anx7625_reg_write(ctx, ctx->i2c.tx_p2_client,
+				 HPD_DET_TIMER_BIT16_23,
+				 (HPD_TIME >> 16) & 0xFF);
+	if (ret < 0)
+		return ret;
+
 	return anx7625_reg_read(ctx, ctx->i2c.rx_p0_client, SYSTEM_STSTUS);
 }
 

drivers/gpu/drm/bridge/analogix/anx7625.h

@@ -132,6 +132,12 @@
 #define I2S_SLAVE_MODE 0x08
 #define AUDIO_LAYOUT   0x01
 
+#define HPD_DET_TIMER_BIT0_7   0xea
+#define HPD_DET_TIMER_BIT8_15  0xeb
+#define HPD_DET_TIMER_BIT16_23 0xec
+/* HPD debounce time 2ms for 27M clock */
+#define HPD_TIME               54000
+
 #define AUDIO_CONTROL_REGISTER 0xe6
 #define TDM_TIMING_MODE 0x08