[PATCH] drm/dp: Use large transactions for I2C over AUX

Simon Farnsworth simon.farnsworth at onelan.co.uk
Wed Jan 28 02:45:13 PST 2015


On Wednesday 28 January 2015 11:33:34 Jani Nikula wrote:
> On Wed, 28 Jan 2015, Daniel Vetter <daniel at ffwll.ch> wrote:
> > On Wed, Jan 28, 2015 at 10:59:06AM +0200, Jani Nikula wrote:
> >> On Tue, 27 Jan 2015, Ville Syrjälä <ville.syrjala at linux.intel.com> wrote:
--snip--
> >> > I made the msg size configurable via a module param just to help me test
> >> > this stuff, but I'm thinking we might want to upstream that just to make
> >> > it easier to try smaller message sizes if/when people encounter problematic
> >> > sinks/dongles.
> >> 
> >> How about just letting that happen first, to see if and how the problems
> >> occur? If there's a pattern, maybe we can fall back to 1-byte transfers
> >> in those cases (or even add OUI based quirks). I've grown really
> >> hesitant about adding new module parameters, they are ABI we can't
> >> easily remove/regress once added.
> >
> > module_param_debug takes care of any such risks imo.
> 
> No such thing, maybe you mean module_param_unsafe?
> 
> Jani.

Changing to module_param_unsafe is trivial. That would taint the kernel if
you play with it, hopefully making it clear that this is not permanent ABI.

I'm now seeing the Bizlink adapters fail after about 45 seconds of
isochronous link up, so it'll be a few days before I do a v4 of this patch,
as I need Datapath's assistance analysing the differences in behaviour
between us and Windows).

-- 
Simon Farnsworth
Software Engineer
ONELAN Ltd
http://www.onelan.com
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