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From: Sasha Levin <sashal@kernel.org>
To: stable@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Sasha Levin <sashal@kernel.org>, Dave Airlie <airlied@redhat.com>,
	dri-devel@lists.freedesktop.org
Subject: [PATCH AUTOSEL 3.18 18/26] drm/ast: fixed reading monitor EDID not stable issue
Date: Wed,  5 Dec 2018 04:54:22 -0500	[thread overview]
Message-ID: <20181205095430.8019-18-sashal@kernel.org> (raw)
In-Reply-To: <20181205095430.8019-1-sashal@kernel.org>

From: "Y.C. Chen" <yc_chen@aspeedtech.com>

[ Upstream commit 300625620314194d9e6d4f6dda71f2dc9cf62d9f ]

v1: over-sample data to increase the stability with some specific monitors
v2: refine to avoid infinite loop
v3: remove un-necessary "volatile" declaration

[airlied: fix two checkpatch warnings]

Signed-off-by: Y.C. Chen <yc_chen@aspeedtech.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1542858988-1127-1-git-send-email-yc_chen@aspeedtech.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/ast/ast_mode.c | 36 ++++++++++++++++++++++++++++------
 1 file changed, 30 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/ast/ast_mode.c b/drivers/gpu/drm/ast/ast_mode.c
index a43d81b6d5d1..ba5149a0cb23 100644
--- a/drivers/gpu/drm/ast/ast_mode.c
+++ b/drivers/gpu/drm/ast/ast_mode.c
@@ -965,9 +965,21 @@ static int get_clock(void *i2c_priv)
 {
 	struct ast_i2c_chan *i2c = i2c_priv;
 	struct ast_private *ast = i2c->dev->dev_private;
-	uint32_t val;
+	uint32_t val, val2, count, pass;
+
+	count = 0;
+	pass = 0;
+	val = (ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xb7, 0x10) >> 4) & 0x01;
+	do {
+		val2 = (ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xb7, 0x10) >> 4) & 0x01;
+		if (val == val2) {
+			pass++;
+		} else {
+			pass = 0;
+			val = (ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xb7, 0x10) >> 4) & 0x01;
+		}
+	} while ((pass < 5) && (count++ < 0x10000));
 
-	val = ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xb7, 0x10) >> 4;
 	return val & 1 ? 1 : 0;
 }
 
@@ -975,9 +987,21 @@ static int get_data(void *i2c_priv)
 {
 	struct ast_i2c_chan *i2c = i2c_priv;
 	struct ast_private *ast = i2c->dev->dev_private;
-	uint32_t val;
+	uint32_t val, val2, count, pass;
+
+	count = 0;
+	pass = 0;
+	val = (ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xb7, 0x20) >> 5) & 0x01;
+	do {
+		val2 = (ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xb7, 0x20) >> 5) & 0x01;
+		if (val == val2) {
+			pass++;
+		} else {
+			pass = 0;
+			val = (ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xb7, 0x20) >> 5) & 0x01;
+		}
+	} while ((pass < 5) && (count++ < 0x10000));
 
-	val = ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xb7, 0x20) >> 5;
 	return val & 1 ? 1 : 0;
 }
 
@@ -990,7 +1014,7 @@ static void set_clock(void *i2c_priv, int clock)
 
 	for (i = 0; i < 0x10000; i++) {
 		ujcrb7 = ((clock & 0x01) ? 0 : 1);
-		ast_set_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xb7, 0xfe, ujcrb7);
+		ast_set_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xb7, 0xf4, ujcrb7);
 		jtemp = ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xb7, 0x01);
 		if (ujcrb7 == jtemp)
 			break;
@@ -1006,7 +1030,7 @@ static void set_data(void *i2c_priv, int data)
 
 	for (i = 0; i < 0x10000; i++) {
 		ujcrb7 = ((data & 0x01) ? 0 : 1) << 2;
-		ast_set_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xb7, 0xfb, ujcrb7);
+		ast_set_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xb7, 0xf1, ujcrb7);
 		jtemp = ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xb7, 0x04);
 		if (ujcrb7 == jtemp)
 			break;
-- 
2.17.1

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  parent reply	other threads:[~2018-12-05  9:56 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-05  9:54 [PATCH AUTOSEL 3.18 01/26] ARM: OMAP2+: prm44xx: Fix section annotation on omap44xx_prm_enable_io_wakeup Sasha Levin
2018-12-05  9:54 ` [PATCH AUTOSEL 3.18 02/26] ARM: OMAP1: ams-delta: Fix possible use of uninitialized field Sasha Levin
2018-12-05  9:54 ` [PATCH AUTOSEL 3.18 04/26] s390/cpum_cf: Reject request for sampling in event initialization Sasha Levin
2018-12-05  9:54 ` [PATCH AUTOSEL 3.18 05/26] hwmon: (w83795) temp4_type has writable permission Sasha Levin
2018-12-05  9:54 ` [PATCH AUTOSEL 3.18 06/26] Btrfs: send, fix infinite loop due to directory rename dependencies Sasha Levin
2018-12-05  9:54 ` [PATCH AUTOSEL 3.18 08/26] ASoC: omap-mcpdm: Add pm_qos handling to avoid under/overruns with CPU_IDLE Sasha Levin
2018-12-05  9:54 ` [PATCH AUTOSEL 3.18 09/26] ASoC: omap-dmic: Add pm_qos handling to avoid overruns " Sasha Levin
2018-12-05  9:54 ` [PATCH AUTOSEL 3.18 15/26] KVM: x86: fix empty-body warnings Sasha Levin
2018-12-05  9:54 ` [PATCH AUTOSEL 3.18 17/26] s390/qeth: fix length check in SNMP processing Sasha Levin
2018-12-05  9:54 ` Sasha Levin [this message]
2018-12-05  9:54 ` [PATCH AUTOSEL 3.18 23/26] hfs: do not free node before using Sasha Levin
2018-12-05  9:54 ` [PATCH AUTOSEL 3.18 24/26] hfsplus: " Sasha Levin

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