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

From: Xin Ji <xji@analogixsemi.com>
To: Andrzej Hajda <andrzej.hajda@intel.com>,
	Neil Armstrong <narmstrong@baylibre.com>,
	Robert Foss <robert.foss@linaro.org>,
	Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
	Jonas Karlman <jonas@kwiboo.se>,
	Jernej Skrabec <jernej.skrabec@gmail.com>,
	David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>
Cc: qwen@analogixsemi.com, linux-kernel@vger.kernel.org,
	dri-devel@lists.freedesktop.org, mliu@analogixsemi.com,
	hsinyi@chromium.org, bliang@analogixsemi.com,
	Xin Ji <xji@analogixsemi.com>
Subject: [PATCH] drm/bridge: anx7625: Set HPD irq detect window to 2ms
Date: Sat,  3 Sep 2022 21:08:33 +0800	[thread overview]
Message-ID: <20220903130833.541463-1-xji@analogixsemi.com> (raw)

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>
---
 drivers/gpu/drm/bridge/analogix/anx7625.c | 14 ++++++++++++++
 drivers/gpu/drm/bridge/analogix/anx7625.h |  6 ++++++
 2 files changed, 20 insertions(+)

diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c b/drivers/gpu/drm/bridge/analogix/anx7625.c
index c74b5df4cade..0c323b5a1c99 100644
--- a/drivers/gpu/drm/bridge/analogix/anx7625.c
+++ b/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);
 }
 
diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.h b/drivers/gpu/drm/bridge/analogix/anx7625.h
index e257a84db962..14f33d6be289 100644
--- a/drivers/gpu/drm/bridge/analogix/anx7625.h
+++ b/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
 
-- 
2.25.1

