Re: [PATCH 4/4] Input: goodix - Support interchanging x and y coordinates in hardware

On Thu, 2016-10-27 at 12:42 -0500, Franklin S Cooper Jr wrote:

On 10/27/2016 05:34 AM, Bastien Nocera wrote:

quoted

On Wed, 2016-10-26 at 18:18 -0500, Rob Herring wrote:

quoted

On Thu, Oct 20, 2016 at 02:59:17PM -0500, Franklin S Cooper Jr
wrote:

quoted

<snip>

quoted

I'm not sure I follow why existing properties don't cover this.

Me neither. I certainly don't understand why the driver can't
mangle
the data from the touchscreen all it wants. It's not like user-
space is
talking to the touchscreen directly.

Sorry the above could of been clearer.

Lets ignore talking about X and Y axis for a little bit since that
really depends on the default touchscreen config values and the way
it
is mounted on the touchscreen. Now lets say when your interacting
with
the touchscreen the touchscreen controller outputs a max value of
1280
when moving your finger horizontally and 800 when moving your finger
vertically.

<-1280->
------

quoted

   |  ^
   |  |
   | 800
   |  |

------  V

So no matter what your horizontal range is 0-1280 and your vertical
range is 0-800. Now based on the above diagram you can see that
usually
you want the longer side to have a higher resolution. So you may want
a
vertical range of 0-1280 and a horizontal range from 0-800 instead.

So lets add labels to the original diagram and assume that the x and
y
axis from the driver/user-space perspective is as follows.
<-1280-> (X)
------

quoted

   |  ^
   |  |
   | 800  (Y)
   |  |

------  V

The only thing the driver (software) has the ability to do is change
the
"orientation".

<-1280-> (Y)
------

quoted

   |  ^
   |  |
   | 800  (X)
   |  |

------  V

However, this doesn't change the resolution ie range of values in the
horizontal and vertical direction the touch screen controller will
report. Only the hardware can determine the resolution it will use.
The
interchange bit I set essentially swaps the range that the controller
is
currently programmed to use which in my first diagram the horizontal
range was 0-1280 and my vertical range is 0-800. So by setting this
interchange bit in hardware the horizontal range will now be 0-800
while
the vertical range will be 0-1280 which is what we want.

Does this clarify things? I messed up the second diagram in my commit
message which is probably what caused the confusion.

Looks to me that this should be fixed in the firmware configuration,
which is what Irina's patches allow doing.

If the goal of this series is implementing this, I wouldn't take any of
those patches until we figure out why the firmware config in those
devices isn't set properly.
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html