On 01/29/2013 02:57 PM, Tom Warren wrote:
Stephen,
On Tue, Jan 29, 2013 at 2:08 PM, Stephen Warren swarren@wwwdotorg.org wrote:
On 01/29/2013 01:40 PM, Tom Warren wrote:
Stephen,
On Tue, Jan 29, 2013 at 1:09 PM, Stephen Warren swarren@wwwdotorg.org wrote:
On 01/29/2013 12:19 PM, Tom Warren wrote:
Note that T114 does not have a separate/different DVC (power I2C) controller like T20 - all 5 I2C controllers are identical, but I2C5 is used to designate the controller intended for power control (PWR_I2C in the schematics).
If you do keep this node, it needs the clocks property filled in.
i2c@7000c000 {compatible = "nvidia,tegra114-i2c", "nvidia,tegra20-i2c";The I2C nodes also aren't backwards-compatible.
They were on T30 (same compatible string there, except of course s/114/30/). And the tegra20-i2c is needed for fdtdec.c to find it (compat_names table).
Yes, I believe the HW changes between Tegra20 and Tegra30 were such that the Tegra20 driver would run unmodified on Tegra30 without issue. I don't believe that's the case for Tegra114 though. The solution would be to add the Tegra114 compatible value to the I2C driver so that it can search for both.
Looking at the TRMs for both T30 and T114, I2C looks nearly identical, except for some additional registers tacked onto the end for bus clear support. 99% of the bits appear exactly the same, too (with the addition of a bus clear int bit on T114 in an used bit position). I know next to nothing about I2C, but it appears to me that the current tegra_I2C.c driver should work fine on T114 (and does, since I can probe addresses with it). I don't see a need for a different driver or compat value here.
I Cc'd in Laxman here, since he wrote the Tegra114 I2C support for the kernel. He made the decision that Tegra114 I2C wasn't compatible with Tegra20/30 I2C, and can explain that. Certainly looking at the kernel patch I pointed at, it seems some of the clock divisors must be programmed differently, which certainly seems enough to declare the HW blocks incompatible, even if everything else is identical.
diff --git a/board/nvidia/dts/tegra114-dalmore.dts b/board/nvidia/dts/tegra114-dalmore.dts
That's the way I have it on T30, and looking at arch/arm/boot/dts/tegra30.dtsi in the kernel, all 5 ports are set to 100KHz.
But this is board-specific; it depends on which of the I2C controllers are actually pinmux'd out onto the board (-> which to enable), and which devices are attached to those buses (-> max I2C clock rate). I don't see how Tegra30 nor tegra30.dtsi are relevant here.
I see your point, but I don't know exactly how to find out the proper clock & disable settings for E1611 Dalmore. I'll talk to Yen & peruse the docs.
The board schematics should show which I2C buses are hooked up.