Quoting Amit Nischal (2018-06-06 04:41:46)
To turn on the gpu_gx_gdsc, there is a hardware requirement to
turn on the root clock (GFX3D RCG) first which would be the turn
on signal for the gdsc along with the SW_COLLAPSE. As per the
current implementation of clk_rcg2_shared_ops, it clears the
root_enable bit in the enable() and set_rate() clock ops. But due
to the above said requirement for GFX3D shared RCG, root_enable bit
would be already set by gdsc driver and rcg2_shared_ops should not clear
the root unless the disable is called.
It sounds like the GDSC enable is ANDed with the RCG's root enable
bit?
Does the RCG need to be clocking for the GDSC to actually turn on?
Or is it purely that the enable bit is logically combined that way so
that if the RCG is parented to a PLL that's off the GDSC will still turn
on?
Add support for the same by reusing the existing clk_rcg2_shared_ops
and deriving "clk_rcg2_gfx3d_ops" clk_ops for GFX3D clock to
take care of the root set/clear requirement.
Anyway, this patch will probably significantly change given that the RCG
is a glorified div-2 that muxes between a safe CXO speed and a
configurable PLL frequency. A lot of the logic can probably just be
hardcoded then.
Signed-off-by: Amit Nischal <anischal@xxxxxxxxxxxxxx>
Patch looks sane.
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