[PATCH 1/1] drm/radeon: Fix Asus M2A-VM HDMI EDID error flooding problem

From: reimth
Date: Tue Jun 21 2011 - 21:21:22 EST

From: Thomas Reim <rdratlos@xxxxxxxxxxx>

Some integrated ATI Radeon chipset implementations
(e. g. Asus M2A-VM HDMI) indicate the availability
of a DDC even when there's no monitor connected.
In this case, drm_get_edid() and drm_edid_block_valid()
periodically dump data and kernel errors into system
log files and onto terminals, which lead to an unacceptable
system behaviour.

Tested since kernel 2.35 on Asus M2A-VM HDMI board

Signed-off-by: Thomas Reim <rdratlos@xxxxxxxxxxx>
---
drivers/gpu/drm/radeon/radeon_connectors.c | 21 +++++++++--
drivers/gpu/drm/radeon/radeon_display.c | 11 ++++++
drivers/gpu/drm/radeon/radeon_i2c.c | 55 ++++++++++++++++++++++++++++
drivers/gpu/drm/radeon/radeon_mode.h | 1 +
4 files changed, 85 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/radeon/radeon_connectors.c b/drivers/gpu/drm/radeon/radeon_connectors.c
index cbfca3a..497e32a 100644
--- a/drivers/gpu/drm/radeon/radeon_connectors.c
+++ b/drivers/gpu/drm/radeon/radeon_connectors.c
@@ -825,9 +825,24 @@ radeon_dvi_detect(struct drm_connector *connector, bool force)
int i;
enum drm_connector_status ret = connector_status_disconnected;
bool dret = false;
-
- if (radeon_connector->ddc_bus)
- dret = radeon_ddc_probe(radeon_connector);
+
+ if (radeon_connector->ddc_bus) {
+ /* AMD 690 chipset series HDMI DDC quirk:
+ * Some integrated ATI Radeon chipset implementations (e. g.
+ * Asus M2A-VM HDMI) indicate the availability of a DDC even
+ * when there's no monitor connected to HDMI. For HDMI
+ * connectors we check for the availability of EDID with
+ * at least a correct EDID header and EDID version/revision
+ * information. Only then, DDC is assumed to be available.
+ * This prevents drm_get_edid() and drm_edid_block_valid() of
+ * periodically dumping data and kernel errors into the logs
+ * and onto the terminal, which would lead to an unacceptable
+ * system behaviour */
+ if (connector->connector_type == DRM_MODE_CONNECTOR_HDMIA)
+ dret = radeon_ddc_edid_probe(radeon_connector);
+ else
+ dret = radeon_ddc_probe(radeon_connector);
+ }
if (dret) {
if (radeon_connector->edid) {
kfree(radeon_connector->edid);
diff --git a/drivers/gpu/drm/radeon/radeon_display.c b/drivers/gpu/drm/radeon/radeon_display.c
index 292f73f..550f143 100644
--- a/drivers/gpu/drm/radeon/radeon_display.c
+++ b/drivers/gpu/drm/radeon/radeon_display.c
@@ -715,6 +715,9 @@ static bool radeon_setup_enc_conn(struct drm_device *dev)
if (ret) {
radeon_setup_encoder_clones(dev);
radeon_print_display_setup(dev);
+ /* Is this really required here?
+ Seems to just force drm to dump EDID errors
+ to kernel logs */
list_for_each_entry(drm_connector, &dev->mode_config.connector_list, head)
radeon_ddc_dump(drm_connector);
}
@@ -777,8 +780,16 @@ static int radeon_ddc_dump(struct drm_connector *connector)
if (!radeon_connector->ddc_bus)
return -1;
edid = drm_get_edid(connector, &radeon_connector->ddc_bus->adapter);
+ /* Asus M2A-VM HDMI DDC quirk: Log EDID retrieval status here once,
+ * instead of periodically dumping data and kernel errors into the
+ * logs, if a monitor is not connected to HDMI */
if (edid) {
+ DRM_INFO("Radeon display connector %s: Found valid EDID",
+ drm_get_connector_name(connector));
kfree(edid);
+ } else {
+ DRM_INFO("Radeon display connector %s: No display connected or invalid EDID",
+ drm_get_connector_name(connector));
}
return ret;
}
diff --git a/drivers/gpu/drm/radeon/radeon_i2c.c b/drivers/gpu/drm/radeon/radeon_i2c.c
index 781196d..80b871f 100644
--- a/drivers/gpu/drm/radeon/radeon_i2c.c
+++ b/drivers/gpu/drm/radeon/radeon_i2c.c
@@ -63,6 +63,61 @@ bool radeon_ddc_probe(struct radeon_connector *radeon_connector)
return false;
}

+/*
+ * Probe EDID information via I2C:
+ * Try to fetch EDID information by calling i2c_transfer driver function and
+ * probe for valid EDID header and version information.
+ *
+ * AMD 690 chipset series HDMI DDC quirk:
+ * Some integrated ATI Radeon chipset implementations (e. g. Asus M2A-VM HDMI
+ * indicate the availability of a DDC even when there's no monitor connected.
+ * Invalid EDID leads to flooding of logs and terminals with error messages
+ */
+bool radeon_ddc_edid_probe(struct radeon_connector *radeon_connector)
+{
+ u8 out_buf[] = {0x0, 0x0};
+ u8 block[20];
+ int ret;
+ struct i2c_msg msgs[] = {
+ {
+ .addr = 0x50,
+ .flags = 0,
+ .len = 1,
+ .buf = out_buf,
+ }, {
+ .addr = 0x50,
+ .flags = I2C_M_RD,
+ .len = 20,
+ .buf = block,
+ }
+ };
+
+ /* on hw with routers, select right port */
+ if (radeon_connector->router.ddc_valid)
+ radeon_router_select_ddc_port(radeon_connector);
+
+ ret = i2c_transfer(&radeon_connector->ddc_bus->adapter, msgs, 2);
+ if (ret == 2)
+ if (block[0] == 0x00 &&
+ block[7] == 0x00 &&
+ block[1] == 0xff &&
+ block[2] == 0xff &&
+ block[3] == 0xff &&
+ block[4] == 0xff &&
+ block[5] == 0xff &&
+ block[6] == 0xff)
+ /* EDID header starts with:
+ * 0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x00
+ */
+ if (block[18] != 0x00 || block[19] != 0x00)
+ /* EDID header ends with EDID version and
+ * revision number <> 0.0
+ */
+ return true;
+ /* Couldn't find an accessible EDID on this connector */
+ return false;
+}
+
/* bit banging i2c */

static void radeon_i2c_do_lock(struct radeon_i2c_chan *i2c, int lock_state)
diff --git a/drivers/gpu/drm/radeon/radeon_mode.h b/drivers/gpu/drm/radeon/radeon_mode.h
index 6df4e3c..14710fc 100644
--- a/drivers/gpu/drm/radeon/radeon_mode.h
+++ b/drivers/gpu/drm/radeon/radeon_mode.h
@@ -515,6 +515,7 @@ extern void radeon_i2c_put_byte(struct radeon_i2c_chan *i2c,
extern void radeon_router_select_ddc_port(struct radeon_connector *radeon_connector);
extern void radeon_router_select_cd_port(struct radeon_connector *radeon_connector);
extern bool radeon_ddc_probe(struct radeon_connector *radeon_connector);
+extern bool radeon_ddc_edid_probe(struct radeon_connector *radeon_connector);
extern int radeon_ddc_get_modes(struct radeon_connector *radeon_connector);

extern struct drm_encoder *radeon_best_encoder(struct drm_connector *connector);
--
1.7.1

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