[PATCH] drm/ast: fixed reading monitor EDID not stable issue

[Y.C. Chen]

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

over-sample data to increase the stability with some specific monitors

Signed-off-by: Y.C. Chen <yc_c...@aspeedtech.com>
---
 drivers/gpu/drm/ast/ast_mode.c | 32 ++++++++++++++++++++++++++------
 1 file changed, 26 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/ast/ast_mode.c b/drivers/gpu/drm/ast/ast_mode.c
index 5e77d45..22e80c0 100644
--- a/drivers/gpu/drm/ast/ast_mode.c
+++ b/drivers/gpu/drm/ast/ast_mode.c
@@ -972,9 +972,19 @@ 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;
+       volatile uint32_t val, val2, count;
+
+       count = 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) count++;
+               else {
+                       count = 0;
+                       val   = (ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 
0xb7, 0x10) >> 4) & 0x01;
+               }
+       } while (count < 5);
 
-       val = ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xb7, 0x10) >> 4;
        return val & 1 ? 1 : 0;
 }
 
@@ -982,9 +992,19 @@ 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;
+       volatile uint32_t val, val2, count;
+
+       count = 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) count++;
+               else {
+                       count = 0;
+                       val   = (ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 
0xb7, 0x20) >> 5) & 0x01;
+               }
+       } while (count < 5);
 
-       val = ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xb7, 0x20) >> 5;
        return val & 1 ? 1 : 0;
 }
 
@@ -997,7 +1017,7 @@ 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;
@@ -1013,7 +1033,7 @@ 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;
-- 
1.8.3.1

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel