drm: Eliminate magic I2C frobbing when reading EDID

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>

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index ca9c616..c4d9b33 100644 (file)
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -584,85 +584,13 @@ int drm_do_probe_ddc_edid(struct i2c_adapter *adapter,
 }
 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,
                             struct i2c_adapter *adapter,
                             char *buf, int len)
 {
        int ret;
 
-       ret = drm_ddc_read(adapter, buf, len);
+       ret = drm_do_probe_ddc_edid(adapter, buf, len);
        if (ret != 0) {
                dev_info(&connector->dev->pdev->dev, "%s: no EDID data\n",
                         drm_get_connector_name(connector));