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Subject[PATCH 4.19 111/142] drm/ast: fixed reading monitor EDID not stable issue
Date
4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

[ 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 7c6ac3cadb6b..8bb355d5d43d 100644
--- a/drivers/gpu/drm/ast/ast_mode.c
+++ b/drivers/gpu/drm/ast/ast_mode.c
@@ -973,9 +973,21 @@ 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;
}

@@ -983,9 +995,21 @@ 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;
}

@@ -998,7 +1022,7 @@ 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;
@@ -1014,7 +1038,7 @@ 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;
--
2.19.1


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