drm/ast: fixed reading monitor EDID not stable issue

From: "Y.C. Chen" <[email protected]>

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

Signed-off-by Y.C. Chen <[email protected]>

---
 drivers/gpu/drm/ast/ast_mode.c | 32 ++++++++++++++++++++++++++------
 1 file changed, 26 insertions(+), 6 deletions(-)

drivers/gpu/drm/ast/ast_mode.c +2 -1

index 5e77d45..22e80c0 100644
@@ -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;
+

From: "Y.C. Chen" <[email protected]>

v1: over-sample data to increase the stability with some specific monitors
v2: refine to avoid infinite loop

Signed-off-by Y.C. Chen <[email protected]>

---
 drivers/gpu/drm/ast/ast_mode.c | 34 ++++++++++++++++++++++++++++------
 1 file changed, 28 insertions(+), 6 deletions(-)

drivers/gpu/drm/ast/ast_mode.c +28 -7

index 5e77d45..092e9a7 100644
@@ -972,9 +972,20 @@ 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, 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;
 }

@@ -982,9 +993,20 @@ 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, 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;
 }
 

@@ -997,7 +1019,7 @@ 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 +1035,7 @@ 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
[email protected]
https://lists.freedesktop.org/mailman/listinfo/dri-devel

Quoted 4 lines

From: "Y.C. Chen" <[email protected]>

v1: over-sample data to increase the stability with some specific

monitors

Quoted 1 line

v2: refine to avoid infinite loop

This contains at least 4 whitespace breakages (val =) in a few places, also why the volatiles, I don't think they make much sense here, have you verified they are required?

Dave.

Review

Quoted 7 lines

Signed-off-by Y.C. Chen <[email protected]>

---
 drivers/gpu/drm/ast/ast_mode.c | 34 ++++++++++++++++++++++++++++------
 1 file changed, 28 insertions(+), 6 deletions(-)

(quoted diff) +0 -0

b/drivers/gpu/drm/ast/ast_mode.c

drivers/gpu/drm/ast/ast_mode.c static int get_clock(void *i2c_priv) · line 979

Quoted 13 lines

index 5e77d45..092e9a7 100644

drivers/gpu/drm/ast/ast_mode.c +5 -1

@@ -972,9 +972,20 @@ 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, pass;
+
+       count = 0;
+       pass  = 0;
+       val   = (ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xb7,

0x10) >> 4) & 0x01;

drivers/gpu/drm/ast/ast_mode.c static int get_clock(void *i2c_priv) · line 981

Quoted 2 lines

drivers/gpu/drm/ast/ast_mode.c +2 -0

+       do {
+               val2 = (ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT,

0xb7, 0x10) >> 4) & 0x01;

drivers/gpu/drm/ast/ast_mode.c static int get_clock(void *i2c_priv)

Quoted 4 lines

drivers/gpu/drm/ast/ast_mode.c +4 -0

+               if (val == val2) pass++;
+               else {
+                       pass = 0;
+                       val   = (ast_get_index_reg_mask(ast,

AST_IO_CRTC_PORT, 0xb7, 0x10) >> 4) & 0x01;

Quoted 9 lines

drivers/gpu/drm/ast/ast_mode.c +2 -1

+               }
+       } while ((pass < 5) && (count++ < 0x10000));
 
-       val = ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xb7, 0x10)
 > 4;
        return val & 1 ? 1 : 0;
 }

drivers/gpu/drm/ast/ast_mode.c static int get_data(void *i2c_priv) · line 1000

Quoted 9 lines

drivers/gpu/drm/ast/ast_mode.c +5 -1

@@ -982,9 +993,20 @@ 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, pass;
+
+       count = 0;
+       pass  = 0;
+       val   = (ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xb7,

0x20) >> 5) & 0x01;

drivers/gpu/drm/ast/ast_mode.c static int get_data(void *i2c_priv) · line 1002

Quoted 2 lines

drivers/gpu/drm/ast/ast_mode.c +2 -0

+       do {
+               val2 = (ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT,

0xb7, 0x20) >> 5) & 0x01;

drivers/gpu/drm/ast/ast_mode.c static int get_clock(void *i2c_priv)

Quoted 4 lines

drivers/gpu/drm/ast/ast_mode.c +4 -0

+               if (val == val2) pass++;
+               else {
+                       pass = 0;
+                       val   = (ast_get_index_reg_mask(ast,

AST_IO_CRTC_PORT, 0xb7, 0x20) >> 5) & 0x01;

drivers/gpu/drm/ast/ast_mode.c static void set_clock(void *i2c_priv, int clock) · line 1000

Quoted 13 lines

drivers/gpu/drm/ast/ast_mode.c +2 -2

+               }
+       } while ((pass < 5) && (count++ < 0x10000));
 
-       val = ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xb7, 0x20)
 > 5;
        return val & 1 ? 1 : 0;
 }

@@ -997,7 +1019,7 @@ 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);

drivers/gpu/drm/ast/ast_mode.c static void set_clock(void *i2c_priv, int clock) · line 1022

Quoted 1 line

drivers/gpu/drm/ast/ast_mode.c +1 -0

+               ast_set_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xb7,

0xf4, ujcrb7);

drivers/gpu/drm/ast/ast_mode.c static void set_clock(void *i2c_priv, int clock) · line 1023

Quoted 1 line

drivers/gpu/drm/ast/ast_mode.c +0 -0

                jtemp = ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT,

0xb7, 0x01);

Quoted 4 lines

drivers/gpu/drm/ast/ast_mode.c +0 -0

                if (ujcrb7 == jtemp)
                        break;

@@ -1013,7 +1035,7 @@ static void set_data(void *i2c_priv, int data)
 

drivers/gpu/drm/ast/ast_mode.c static void set_data(void *i2c_priv, int data)

Quoted 3 lines

drivers/gpu/drm/ast/ast_mode.c +0 -1

        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);

drivers/gpu/drm/ast/ast_mode.c static void set_data(void *i2c_priv, int data) · line 1038

Quoted 1 line

drivers/gpu/drm/ast/ast_mode.c +1 -0

+               ast_set_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xb7,

0xf1, ujcrb7);

drivers/gpu/drm/ast/ast_mode.c static void set_data(void *i2c_priv, int data) · line 1039

Quoted 1 line

drivers/gpu/drm/ast/ast_mode.c +0 -0

                jtemp = ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT,

0xb7, 0x04);

Quoted 9 lines

drivers/gpu/drm/ast/ast_mode.c +0 -1

                if (ujcrb7 == jtemp)
                        break;
--

1.8.3.1

_______________________________________________
dri-devel mailing list
[email protected]
https://lists.freedesktop.org/mailman/listinfo/dri-devel

Hi Dave,
Thanks for your feedback. No issue found actually if I remove "volatile" on my platform. In my experience, if the value is volatile, adding "volatile" will be safer and no harm, that is why I add it by default. If you think it is not necessary, it's ok for me to remove it.