Re: [PATCH] drm/i915/dp: Fix I2C/EDID handling with active DisplayPort to DVI converter

On Wed, 8 Dec 2010 16:10:21 +0000, David Flynn davidf@rd.bbc.co.uk wrote:

The DisplayPort standard (1.1a) states that: The I2C-over-AUX Reply field is valid only when Native AUX CH Reply field is AUX_ACK (00). When Native AUX CH Reply field is not 00, then, I2C-over-AUX Reply field must be 00 and be ignored.

This fixes broken EDID reading when using an active DisplayPort to duallink DVI converter. If the AUX CH replier chooses to defer the transaction, a short read occurs and erroneous data is returned as the i2c reply due to a lack of length checking and failure to check for AUX ACK.

And it didn't break my bog standard DP setup. :) Applied to -fixes and tagged for stable.

Thanks, -Chris