Hello Dave,
My patch-set for adding support for 4 block EDID is now reviewed and ready.
Please let me know if you want any further clarification
Regards,
Shirish S
On Thu, Aug 30, 2012 at 12:04 AM, Shirish S <s.shir...@samsung.com> 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.shir...@samsung.com>
> Reviewed-by: Jean Delvare <jdelv...@suse.de>
> Reviewed-by: Daniel Vetter <daniel.vet...@ffwll.ch>
> Reviewed-by: Ville Syrjala <ville.syrj...@linux.intel.com>
> ---
> drivers/gpu/drm/drm_edid.c | 19 ++++++++++++++++---
> 1 files changed, 16 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index bcc4725..7f62de5 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
> @@ -265,6 +267,11 @@ drm_do_probe_ddc_edid(struct i2c_adapter *adapter,
> unsigned char *buf,
> do {
> struct i2c_msg msgs[] = {
> {
> + .addr = DDC_SEGMENT_ADDR,
> + .flags = 0,
> + .len = 1,
> + .buf = &segment,
> + }, {
> .addr = DDC_ADDR,
> .flags = 0,
> .len = 1,
> @@ -276,15 +283,21 @@ 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.
> + */
> + ret = i2c_transfer(adapter, &msgs[3 - xfers], 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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>
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