From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Warren Date: Tue, 29 Jan 2013 15:13:59 -0700 Subject: [U-Boot] [PATCH 1/2] Tegra114: fdt: Update DT files with I2C info for T114/Dalmore In-Reply-To: References: <1359487175-21064-1-git-send-email-twarren@nvidia.com> <1359487175-21064-2-git-send-email-twarren@nvidia.com> <51082C70.3040108@wwwdotorg.org> <51083A69.5090108@wwwdotorg.org> Message-ID: <510849A7.8000301@wwwdotorg.org> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On 01/29/2013 02:57 PM, Tom Warren wrote: > Stephen, > > On Tue, Jan 29, 2013 at 2:08 PM, Stephen Warren wrote: >> On 01/29/2013 01:40 PM, Tom Warren wrote: >>> Stephen, >>> >>> On Tue, Jan 29, 2013 at 1:09 PM, Stephen Warren 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 at 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.