On Fri, Oct 07, 2011 at 07:00:42PM -0300, Eugeni Dodonov wrote: > This adds a new function intel_drm_get_valid_edid, which is used instead > of drm_get_edid within the i915 driver. > > It does a similar check to the one in previous patch, but it is limited to > i915 driver. > > The check is similar to the first part of EDID discovery performed by the > drm_do_probe_ddc_edid. In case the i2c_transfer fails with the -ENXIO > result, we know that the i2c_algo_bit was unable to locate the hardware, > so we give up on further edid discovery. > > They should also fix https://bugs.freedesktop.org/show_bug.cgi?id=41059 > > v2: change printk level to KERN_DEBUG to avoid filling up dmesg > > Signed-off-by: Eugeni Dodonov <eugeni.dodonov at intel.com> > --- > > diff --git a/drivers/gpu/drm/i915/intel_i2c.c > b/drivers/gpu/drm/i915/intel_i2c.c > index d98cee6..77115b9 100644 > --- a/drivers/gpu/drm/i915/intel_i2c.c > +++ b/drivers/gpu/drm/i915/intel_i2c.c > @@ -470,3 +470,36 @@ void intel_teardown_gmbus(struct drm_device *dev) > kfree(dev_priv->gmbus); > dev_priv->gmbus = NULL; > } > + > +/** > + * intel_drm_get_valid_edid - gets edid from existent adapters only > + * @connector: DRM connector device to use > + * @adapter: i2c adapter > + * > + * Verifies if the i2c adapter is responding to our queries before > + * attempting to do proper communication with it. If it does, > + * retreive the EDID with help of drm_get_edid > + */ > +struct edid * > +intel_drm_get_valid_edid(struct drm_connector *connector, > + struct i2c_adapter *adapter) > +{ > + unsigned char out; > + int ret; > + struct i2c_msg msgs[] = { > + { > + .addr = 0x50, > + .flags = 0, > + .len = 1, > + .buf = &out, > + } > + }; > + /* Let's try one edid transfer */ > + ret = i2c_transfer(adapter, msgs, 1); > + if (ret == -ENXIO) { > + printk(KERN_DEBUG "i915: adapter %s not responding: %d\n", > + adapter->name, ret); > + return NULL; > + } > + return drm_get_edid(connector, adapter); > +}
I think you may as well optimistically try to get the edid_data here. The problem is, in the success case you add ~10 i2c clocks because you next call drm_get_edid. If you optimistacally try to do both you should receive the -ENXIO after the slaves ignore the address byte, and not lose time. (So win on exists case, lose a *slight* amount of CPU time in fail case). Now if you do that I think most of the code can be taken from intel_ddc_probe. Just modify that function to take the args you need (dev_priv, and adatper I am thinking). I only see one caller of that function, which can easily be modified. Ben
