Re: [PATCH V4] drm: edid: add support for E-DDC

On Sat, Aug 25, 2012 at 03:13:56PM +0530, Shirish S wrote:

The current logic for probing ddc is limited to 2 blocks (256 bytes), this patch adds support for the 4 block (512) data.

To do this, a single 8-bit segment index is passed to the display via the I2C address 30h. Data from the selected segment is then immediately read via the regular DDC2 address using a repeated I2C 'START' signal.

Signed-off-by: Shirish S s.shirish@samsung.com

Looks good.

Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch

---

drivers/gpu/drm/drm_edid.c | 22 ++++++++++++++++++---- 1 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c index a8743c3..cde7af0 100644 --- a/drivers/gpu/drm/drm_edid.c +++ b/drivers/gpu/drm/drm_edid.c @@ -254,6 +254,8 @@ drm_do_probe_ddc_edid(struct i2c_adapter *adapter, unsigned char *buf, int block, int len) { unsigned char start = block * EDID_LENGTH;

• unsigned char segment = block >> 1;

• unsigned char xfers = segment ? 3 : 2; int ret, retries = 5;

  /* The core i2c driver will automatically retry the transfer if the

@@ -264,7 +266,12 @@ drm_do_probe_ddc_edid(struct i2c_adapter *adapter, unsigned char *buf, */ do { struct i2c_msg msgs[] = {

• 	{
  

• 	{ /*set segment pointer */
  

• 		.addr	= DDC_SEGMENT_ADDR,
  

• 		.flags	= segment ? 0 : I2C_M_IGNORE_NAK,
  

• 		.len	= 1,
  

• 		.buf	= &segment,
  

• 	}, {
  	.addr	= DDC_ADDR,
  	.flags	= 0,
  	.len	= 1,
  

@@ -276,15 +283,22 @@ drm_do_probe_ddc_edid(struct i2c_adapter *adapter, unsigned char *buf, .buf = buf, } };

• ret = i2c_transfer(adapter, msgs, 2);
  

• /* Avoid sending the segment addr to not upset non-compliant ddc

• * monitors.
  

• */
  

• if (!segment)
  

• 	ret = i2c_transfer(adapter, &msgs[1], xfers);
  

• else
  

• 	ret = i2c_transfer(adapter, msgs, xfers);
  

• if (ret == -ENXIO) { DRM_DEBUG_KMS("drm: skipping non-existent adapter %s\n", adapter->name); break; }

• } while (ret != 2 && --retries);

• } while (ret != xfers && --retries);

• return ret == 2 ? 0 : -1;

• return ret == xfers ? 0 : -1;

}

static bool drm_edid_is_zero(u8 *in_edid, int length)

1.7.0.4

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