On 06/17/2014 07:15 PM, Stephen Warren wrote:
On 06/17/2014 06:16 AM, Tomeu Vizoso wrote:
On 06/16/2014 10:02 PM, Stephen Warren wrote:
On 06/16/2014 07:35 AM, Tomeu Vizoso wrote:
This binding looks quite anaemic vs.
Documentation/devicetree/bindings/arm/tegra/nvidia,tegra20-emc.txt; I
would expect that this binding needs all the EMC register data from the
tegra20-emc binding too. Can the two bindings be identical?
There's even less stuff needed right now, as all what ultimately the EMC
driver does is call clk_set_rate on the EMC clock. As the T124 EMC
driver gains more features, they should get more similar.
IIRC, even changing the EMC clock rate requires modifying the memory
controller's programming (e.g. delays/taps/tuning etc.). That's exactly
what the more complex stuff in the nvidia,tegra20-emc.txt is all about.
I not convinced that a driver that just modifies the clock rate without
adjusting the EMC programming will work reliably.
Indeed, changing the EMC clock rate is a somewhat complicated sequence
of ~10 steps. The kernel even won't let one the rate be change directly,
as the change would be propagated to PLL_M which cannot have its rate
changed while it is enabled. I suppose the sequence should be hidden in
the EMC clk's set_rate implementation, which I guess would leave just
the rate policy to this driver.
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