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drm: Eliminate magic I2C frobbing when reading EDID

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This code depends on the underlying I2C adapter using the bit-banging algo,
which may not be the case. If specific encoders require this mechanism, they
should build a custom I2C algo that implements this workaround, rather than
having it in the general path.

Signed-off-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
Keith Packard 2009-05-30 20:42:27 -07:00 committed by Dave Airlie
parent 7ff145593d
commit 61f11699e7
1 changed files with 1 additions and 73 deletions
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74
drivers/gpu/drm/drm_edid.c
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@ -584,85 +584,13 @@ int drm_do_probe_ddc_edid(struct i2c_adapter *adapter,
} }
EXPORT_SYMBOL(drm_do_probe_ddc_edid); EXPORT_SYMBOL(drm_do_probe_ddc_edid);
/**
* Get EDID information.
*
* \param adapter : i2c device adaptor.
* \param buf : EDID data buffer to be filled
* \param len : EDID data buffer length
* \return 0 on success or -1 on failure.
*
* Initialize DDC, then fetch EDID information
* by calling drm_do_probe_ddc_edid function.
*/
static int drm_ddc_read(struct i2c_adapter *adapter,
unsigned char *buf, int len)
{
struct i2c_algo_bit_data *algo_data = adapter->algo_data;
int i, j;
int ret = -1;
algo_data->setscl(algo_data->data, 1);
for (i = 0; i < 1; i++) {
/* For some old monitors we need the
* following process to initialize/stop DDC
*/
algo_data->setsda(algo_data->data, 1);
msleep(13);
algo_data->setscl(algo_data->data, 1);
for (j = 0; j < 5; j++) {
msleep(10);
if (algo_data->getscl(algo_data->data))
break;
}
if (j == 5)
continue;
algo_data->setsda(algo_data->data, 0);
msleep(15);
algo_data->setscl(algo_data->data, 0);
msleep(15);
algo_data->setsda(algo_data->data, 1);
msleep(15);
/* Do the real work */
ret = drm_do_probe_ddc_edid(adapter, buf, len);
algo_data->setsda(algo_data->data, 0);
algo_data->setscl(algo_data->data, 0);
msleep(15);
algo_data->setscl(algo_data->data, 1);
for (j = 0; j < 10; j++) {
msleep(10);
if (algo_data->getscl(algo_data->data))
break;
}
algo_data->setsda(algo_data->data, 1);
msleep(15);
algo_data->setscl(algo_data->data, 0);
algo_data->setsda(algo_data->data, 0);
if (ret == 0)
break;
}
/* Release the DDC lines when done or the Apple Cinema HD display
* will switch off
*/
algo_data->setsda(algo_data->data, 1);
algo_data->setscl(algo_data->data, 1);
return ret;
}
static int drm_ddc_read_edid(struct drm_connector *connector, static int drm_ddc_read_edid(struct drm_connector *connector,
struct i2c_adapter *adapter, struct i2c_adapter *adapter,
char *buf, int len) char *buf, int len)
{ {
int ret; int ret;
ret = drm_ddc_read(adapter, buf, len); ret = drm_do_probe_ddc_edid(adapter, buf, len);
if (ret != 0) { if (ret != 0) {
dev_info(&connector->dev->pdev->dev, "%s: no EDID data\n", dev_info(&connector->dev->pdev->dev, "%s: no EDID data\n",
drm_get_connector_name(connector)); drm_get_connector_name(connector));