On 1/13/2018 1:15 AM, Laurent Pinchart wrote:
According to the latest revisions of the R-Car gen3 manual, the LVDS mode
must be set before the LVDS I/O pins are enabled, not after -- fix the
gen3 LVDS startup sequence accordingly...
While at it, also fix the comment preceding the first LVDCR0 write in
the R-Car gen2 startup code that still talks about hardcoding the LVDS
mode 0...
How about fixing that in patch 2/2 that touches the Gen2 initialization
sequence ? I think I'd even go as far as squashing both patches, I don't
think there's a need to split them.
Fixes: e947eccbeba4 ("drm: rcar-du: Add support for LVDS mode selection")
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@xxxxxxxxxxxxxxxxxx>
Is this really needed ? Does it fix a problem you've experienced, or is it
theoretical only ? The mode shouldn't matter before the LVDS internal logic
is turned on. Unless there's a real issue I'm not sure we should make the
code more complex.
Furthermore the datasheet states
"3. This refers to settings other than those that are concerned with LVDS-IF
startup. These items may be set while waiting for the conditions of step 6 to
be met."
Ah, I hadn't paid much attention to this note. Howeve, it seems quite
vague to me... and there's no condition in step 6. ;-)
Doesn't this mean that the mode and input selector don't have to be set as the
very first step, but can be programmed at any point before starting the LVDS
encoder through the PWD bit (on Gen3) or the PLLON bit (on Gen2) ?
Frankly speaking, I don't know how to interpret that note...
[...]
MBR, Sergei
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