Re: [PATCH] drm/bridge: tc358767: Expose test mode functionality via debugfs
From: Tomi Valkeinen
Date: Wed Aug 28 2019 - 01:48:30 EST
On 28/08/2019 01:51, Andrey Smirnov wrote:
The whole point of a
driver is to avoid needing detailed knowledge of the device's internals
in userspace.
You won't avoid needing detailed knowledge of the device's internals
if you don't have a priori knowledge in the form of a agreed upon/well
known abstraction you are exposing from the driver. There is no such
abstraction in this case. Whether you present "tstctl" that takes a
magic value or "red", "green", "blue" and "pattern" taking numbers and
special strings, as a user, you still would have to go read the driver
code in order to figure out how that stuff works.
Given how this is an obscure _debug_ feature for a niche part, I think
exposing raw register and leaving a comment in the driver source code
explaining how it works is reasonably user-friendly (for all 10 - 15
unique users that this feature would ever have).
To avoid any further back and forth of this subject, how about the
following. If this is up to me, then I'd like to move forward to v2
with the interface as is. If you feel strongly about this and insist
on your vision of the interface, please let me know what it looks like
(e.g. is what I described above good enough) and I'll rework v2 to
have that.
I agree, I don't see a point in adding a pile of code to make a device
specific debug feature to hide the device internals. If someone is going
to use this feature, most likely he either has the datasheet or he has
been asked by someone with the datasheet to try the feature.
Tomi
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