[PATCH 0/3] Misc fixes for Tegra

[PATCH 0/3] Misc fixes for Tegra

[tomcwarren3959 at gmail.com]

From: Tom Warren <twarren@nvidia.com>

These fixes originated on our downstream L4T U-Boot, and include
fdt, pll and code relocation changes.

Stephen Warren (1):
  ARM: tegra: p2371-2180: add I2C nodes to DT

Tom Warren (1):
  fdt: Fix 'system' command

Vishruth (1):
  ARM: tegra: p2771-0000: enable PIE relocation

 arch/arm/dts/tegra210-p2371-2180.dts | 18 ++++++++++++++++++
 cmd/fdt.c                            |  2 +-
 configs/p2771-0000-000_defconfig     |  1 +
 configs/p2771-0000-500_defconfig     |  1 +
 4 files changed, 21 insertions(+), 1 deletion(-)

-- 
1.8.2.1.610.g562af5b


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[PATCH 1/3] ARM: tegra: p2771-0000: enable PIE relocation

[tomcwarren3959 at gmail.com]

From: Vishruth <vishruthj@nvidia.com>

U-Boot is configured to build as position independent executable. Enable
relocation of RELA section required to work with different load
addresses.

Signed-off-by: Vishruth <vishruthj@nvidia.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>
---
 configs/p2771-0000-000_defconfig | 1 +
 configs/p2771-0000-500_defconfig | 1 +
 2 files changed, 2 insertions(+)

diff --git a/configs/p2771-0000-000_defconfig b/configs/p2771-0000-000_defconfig
index 06f12e2..e347a77 100644
--- a/configs/p2771-0000-000_defconfig
+++ b/configs/p2771-0000-000_defconfig
@@ -36,3 +36,4 @@ CONFIG_TEGRA186_POWER_DOMAIN=y
 CONFIG_SYS_NS16550=y
 CONFIG_USB=y
 CONFIG_DM_USB=y
+CONFIG_POSITION_INDEPENDENT=y
diff --git a/configs/p2771-0000-500_defconfig b/configs/p2771-0000-500_defconfig
index 1a14a92..0803b26 100644
--- a/configs/p2771-0000-500_defconfig
+++ b/configs/p2771-0000-500_defconfig
@@ -36,3 +36,4 @@ CONFIG_TEGRA186_POWER_DOMAIN=y
 CONFIG_SYS_NS16550=y
 CONFIG_USB=y
 CONFIG_DM_USB=y
+CONFIG_POSITION_INDEPENDENT=y
-- 
1.8.2.1.610.g562af5b


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[PATCH 1/3] ARM: tegra: p2771-0000: enable PIE relocation

[Peter Robinson]

> From: Vishruth <vishruthj@nvidia.com>
>
> U-Boot is configured to build as position independent executable. Enable
> relocation of RELA section required to work with different load
> addresses.
>
> Signed-off-by: Vishruth <vishruthj@nvidia.com>
> Signed-off-by: Tom Warren <twarren@nvidia.com>
Tested-by: Peter Robinson <pbrobinson@gmail.com>

Tested on TX1


> ---
>  configs/p2771-0000-000_defconfig | 1 +
>  configs/p2771-0000-500_defconfig | 1 +
>  2 files changed, 2 insertions(+)
>
> diff --git a/configs/p2771-0000-000_defconfig b/configs/p2771-0000-000_defconfig
> index 06f12e2..e347a77 100644
> --- a/configs/p2771-0000-000_defconfig
> +++ b/configs/p2771-0000-000_defconfig
> @@ -36,3 +36,4 @@ CONFIG_TEGRA186_POWER_DOMAIN=y
>  CONFIG_SYS_NS16550=y
>  CONFIG_USB=y
>  CONFIG_DM_USB=y
> +CONFIG_POSITION_INDEPENDENT=y
> diff --git a/configs/p2771-0000-500_defconfig b/configs/p2771-0000-500_defconfig
> index 1a14a92..0803b26 100644
> --- a/configs/p2771-0000-500_defconfig
> +++ b/configs/p2771-0000-500_defconfig
> @@ -36,3 +36,4 @@ CONFIG_TEGRA186_POWER_DOMAIN=y
>  CONFIG_SYS_NS16550=y
>  CONFIG_USB=y
>  CONFIG_DM_USB=y
> +CONFIG_POSITION_INDEPENDENT=y
> --
> 1.8.2.1.610.g562af5b
>
>
> -----------------------------------------------------------------------------------
> This email message is for the sole use of the intended recipient(s) and may contain
> confidential information.  Any unauthorized review, use, disclosure or distribution
> is prohibited.  If you are not the intended recipient, please contact the sender by
> reply email and destroy all copies of the original message.
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[PATCH 2/3] fdt: Fix 'system' command

[tomcwarren3959 at gmail.com]

From: Tom Warren <twarren@nvidia.com>

'fdt systemsetup' wasn't working, due to the fact that the 'set' command
was being parsed in do_fdt() by only testing for the leading 's' instead
of "se", which kept the "sys" test further down from executing. Changed
to test for "se" instead, now 'fdt systemsetup' works (to test the
ft_system_setup proc w/o having to boot a kernel).

Signed-off-by: Tom Warren <twarren@nvidia.com>
---
 cmd/fdt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/cmd/fdt.c b/cmd/fdt.c
index 25a6ed4..36cc726 100644
--- a/cmd/fdt.c
+++ b/cmd/fdt.c
@@ -286,7 +286,7 @@ static int do_fdt(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 	/*
 	 * Set the value of a property in the working_fdt.
 	 */
-	} else if (argv[1][0] == 's') {
+	} else if (strncmp(argv[1], "se", 2) == 0) {
 		char *pathp;		/* path */
 		char *prop;		/* property */
 		int  nodeoffset;	/* node offset from libfdt */
-- 
1.8.2.1.610.g562af5b


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[PATCH 2/3] fdt: Fix 'system' command

[sjg at google.com]

From: Tom Warren <twarren@nvidia.com>

'fdt systemsetup' wasn't working, due to the fact that the 'set' command
was being parsed in do_fdt() by only testing for the leading 's' instead
of "se", which kept the "sys" test further down from executing. Changed
to test for "se" instead, now 'fdt systemsetup' works (to test the
ft_system_setup proc w/o having to boot a kernel).

Signed-off-by: Tom Warren <twarren@nvidia.com>
---
 cmd/fdt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Applied to u-boot-dm/next, thanks!

[PATCH 3/3] ARM: tegra: p2371-2180: add I2C nodes to DT

[tomcwarren3959 at gmail.com]

From: Stephen Warren <swarren@nvidia.com>

This adds to the DT the I2C controllers that connect to the board ID EEPROM,
camera board EEPROM, etc. With this change, you can now probe all I2C devices
on a TX1 board.

Signed-off-by: Tom Warren <twarren@nvidia.com>
---
 arch/arm/dts/tegra210-p2371-2180.dts | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/arch/arm/dts/tegra210-p2371-2180.dts b/arch/arm/dts/tegra210-p2371-2180.dts
index c2f497c..d982b5f 100644
--- a/arch/arm/dts/tegra210-p2371-2180.dts
+++ b/arch/arm/dts/tegra210-p2371-2180.dts
@@ -12,6 +12,9 @@
 
 	aliases {
 		i2c0 = "/i2c at 7000d000";
+		i2c2 = "/i2c at 7000c400";
+		i2c3 = "/i2c at 7000c500";
+		i2c5 = "/i2c at 546c0c00";
 		mmc0 = "/sdhci at 700b0600";
 		mmc1 = "/sdhci at 700b0000";
 		usb0 = "/usb at 7d000000";
@@ -33,6 +36,11 @@
 		};
 	};
 
+	i2c at 546c0c00 {
+		status = "okay";
+		clock-frequency = <400000>;
+	};
+
 	padctl at 7009f000 {
 		pinctrl-0 = <&padctl_default>;
 		pinctrl-names = "default";
@@ -85,6 +93,16 @@
 		non-removable;
 	};
 
+	i2c at 7000c400 {
+		status = "okay";
+		clock-frequency = <400000>;
+	};
+
+	i2c at 7000c500 {
+		status = "okay";
+		clock-frequency = <400000>;
+	};
+
 	i2c at 7000d000 {
 		status = "okay";
 		clock-frequency = <400000>;
-- 
1.8.2.1.610.g562af5b


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[PATCH 3/3] ARM: tegra: p2371-2180: add I2C nodes to DT

[Peter Robinson]

> From: Stephen Warren <swarren@nvidia.com>
>
> This adds to the DT the I2C controllers that connect to the board ID EEPROM,
> camera board EEPROM, etc. With this change, you can now probe all I2C devices
> on a TX1 board.
>
> Signed-off-by: Tom Warren <twarren@nvidia.com>
> ---
>  arch/arm/dts/tegra210-p2371-2180.dts | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
>
> diff --git a/arch/arm/dts/tegra210-p2371-2180.dts b/arch/arm/dts/tegra210-p2371-2180.dts
> index c2f497c..d982b5f 100644
> --- a/arch/arm/dts/tegra210-p2371-2180.dts
> +++ b/arch/arm/dts/tegra210-p2371-2180.dts
> @@ -12,6 +12,9 @@
>
>         aliases {
>                 i2c0 = "/i2c at 7000d000";
> +               i2c2 = "/i2c at 7000c400";
> +               i2c3 = "/i2c at 7000c500";
> +               i2c5 = "/i2c at 546c0c00";

I don't think this is correct, it doesn't show up in U-Boot with the
"i2c bus" command where the others do, looking in the tegra210.dtsi it
looks like it should be i2c at 546c0000?

>                 mmc0 = "/sdhci at 700b0600";
>                 mmc1 = "/sdhci at 700b0000";
>                 usb0 = "/usb at 7d000000";
> @@ -33,6 +36,11 @@
>                 };
>         };
>
> +       i2c at 546c0c00 {
> +               status = "okay";
> +               clock-frequency = <400000>;
> +       };
> +
>         padctl at 7009f000 {
>                 pinctrl-0 = <&padctl_default>;
>                 pinctrl-names = "default";
> @@ -85,6 +93,16 @@
>                 non-removable;
>         };
>
> +       i2c at 7000c400 {
> +               status = "okay";
> +               clock-frequency = <400000>;
> +       };
> +
> +       i2c at 7000c500 {
> +               status = "okay";
> +               clock-frequency = <400000>;
> +       };
> +
>         i2c at 7000d000 {
>                 status = "okay";
>                 clock-frequency = <400000>;
> --
> 1.8.2.1.610.g562af5b
>
>
> -----------------------------------------------------------------------------------
> This email message is for the sole use of the intended recipient(s) and may contain
> confidential information.  Any unauthorized review, use, disclosure or distribution
> is prohibited.  If you are not the intended recipient, please contact the sender by
> reply email and destroy all copies of the original message.
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[PATCH 3/3] ARM: tegra: p2371-2180: add I2C nodes to DT

[Tom Warren]

-----Original Message-----
From: Peter Robinson <pbrobinson@gmail.com> 
Sent: Tuesday, March 31, 2020 3:54 AM
To: tomcwarren3959 at gmail.com
Cc: u-boot at lists.denx.de; Stephen Warren <swarren@nvidia.com>; Thierry Reding <treding@nvidia.com>; Jonathan Hunter <jonathanh@nvidia.com>; Tom Warren <TWarren@nvidia.com>; Vishruth Jain <vishruthj@nvidia.com>
Subject: Re: [PATCH 3/3] ARM: tegra: p2371-2180: add I2C nodes to DT

External email: Use caution opening links or attachments


> From: Stephen Warren <swarren@nvidia.com>
>
> This adds to the DT the I2C controllers that connect to the board ID 
> EEPROM, camera board EEPROM, etc. With this change, you can now probe 
> all I2C devices on a TX1 board.
>
> Signed-off-by: Tom Warren <twarren@nvidia.com>
> ---
>  arch/arm/dts/tegra210-p2371-2180.dts | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
>
> diff --git a/arch/arm/dts/tegra210-p2371-2180.dts 
> b/arch/arm/dts/tegra210-p2371-2180.dts
> index c2f497c..d982b5f 100644
> --- a/arch/arm/dts/tegra210-p2371-2180.dts
> +++ b/arch/arm/dts/tegra210-p2371-2180.dts
> @@ -12,6 +12,9 @@
>
>         aliases {
>                 i2c0 = "/i2c at 7000d000";
> +               i2c2 = "/i2c at 7000c400";
> +               i2c3 = "/i2c at 7000c500";
> +               i2c5 = "/i2c at 546c0c00";

I don't think this is correct, it doesn't show up in U-Boot with the "i2c bus" command where the others do, looking in the tegra210.dtsi it looks like it should be i2c at 546c0000?
[Tom] That I2C address is working in downstream (L4T) TX1 U-Boot.  The VI_I2C controller is a little weird, it's normal I2C registers are offset from base by 0xC00.  A different driver is needed, but I haven't posted it yet upstream.  I should probably drop if from the DTS for now until I post the VI_I2C driver.

--nvpublic

>                 mmc0 = "/sdhci at 700b0600";
>                 mmc1 = "/sdhci at 700b0000";
>                 usb0 = "/usb at 7d000000"; @@ -33,6 +36,11 @@
>                 };
>         };
>
> +       i2c at 546c0c00 {
> +               status = "okay";
> +               clock-frequency = <400000>;
> +       };
> +
>         padctl at 7009f000 {
>                 pinctrl-0 = <&padctl_default>;
>                 pinctrl-names = "default"; @@ -85,6 +93,16 @@
>                 non-removable;
>         };
>
> +       i2c at 7000c400 {
> +               status = "okay";
> +               clock-frequency = <400000>;
> +       };
> +
> +       i2c at 7000c500 {
> +               status = "okay";
> +               clock-frequency = <400000>;
> +       };
> +
>         i2c at 7000d000 {
>                 status = "okay";
>                 clock-frequency = <400000>;
> --
> 1.8.2.1.610.g562af5b
>
>
> ----------------------------------------------------------------------
> ------------- This email message is for the sole use of the intended 
> recipient(s) and may contain confidential information.  Any 
> unauthorized review, use, disclosure or distribution is prohibited.  
> If you are not the intended recipient, please contact the sender by 
> reply email and destroy all copies of the original message.
> ----------------------------------------------------------------------
> -------------

[PATCH 3/3] ARM: tegra: p2371-2180: add I2C nodes to DT

[Thierry Reding]

On Wed, Apr 01, 2020 at 02:03:09AM +0200, Tom Warren wrote:
> -----Original Message-----
> From: Peter Robinson <pbrobinson@gmail.com> 
> Sent: Tuesday, March 31, 2020 3:54 AM
> To: tomcwarren3959 at gmail.com
> Cc: u-boot at lists.denx.de; Stephen Warren <swarren@nvidia.com>; Thierry Reding <treding@nvidia.com>; Jonathan Hunter <jonathanh@nvidia.com>; Tom Warren <TWarren@nvidia.com>; Vishruth Jain <vishruthj@nvidia.com>
> Subject: Re: [PATCH 3/3] ARM: tegra: p2371-2180: add I2C nodes to DT
> 
> External email: Use caution opening links or attachments
> 
> 
> > From: Stephen Warren <swarren@nvidia.com>
> >
> > This adds to the DT the I2C controllers that connect to the board ID 
> > EEPROM, camera board EEPROM, etc. With this change, you can now probe 
> > all I2C devices on a TX1 board.
> >
> > Signed-off-by: Tom Warren <twarren@nvidia.com>
> > ---
> >  arch/arm/dts/tegra210-p2371-2180.dts | 18 ++++++++++++++++++
> >  1 file changed, 18 insertions(+)
> >
> > diff --git a/arch/arm/dts/tegra210-p2371-2180.dts 
> > b/arch/arm/dts/tegra210-p2371-2180.dts
> > index c2f497c..d982b5f 100644
> > --- a/arch/arm/dts/tegra210-p2371-2180.dts
> > +++ b/arch/arm/dts/tegra210-p2371-2180.dts
> > @@ -12,6 +12,9 @@
> >
> >         aliases {
> >                 i2c0 = "/i2c at 7000d000";
> > +               i2c2 = "/i2c at 7000c400";
> > +               i2c3 = "/i2c at 7000c500";
> > +               i2c5 = "/i2c at 546c0c00";
> 
> I don't think this is correct, it doesn't show up in U-Boot with the
> "i2c bus" command where the others do, looking in the tegra210.dtsi it
> looks like it should be i2c at 546c0000?
> [Tom] That I2C address is working in downstream (L4T) TX1 U-Boot.  The
> VI_I2C controller is a little weird, it's normal I2C registers are
> offset from base by 0xC00.  A different driver is needed, but I
> haven't posted it yet upstream.  I should probably drop if from the
> DTS for now until I post the VI_I2C driver.

I think the problem here is that the upstream U-Boot device tree doesn't
contain an i2c at 546c0c00 node. Instead it has i2c at 546c0000, which we also
have in the upstream kernel. My recollection is that that's also the
address listed in the Tegra210 system address map of the TRM and there
are some registers before the regular I2C interface at offset 0xc00.

I've been carrying a patch against the upstream Linux I2C controller
driver to special-case the VI/I2C to always add that 0xc00 offset when
accessing registers, which allows us to reuse the existing driver and at
the same time keeps all registers mapped so we can also access the
VI/I2C specific registers.

My recollection is that the U-Boot driver is fairly similar to the Linux
driver, so I suspect something similar could be done.

Thierry
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[PATCH 3/3] ARM: tegra: p2371-2180: add I2C nodes to DT

[Tom Warren]

-----Original Message-----
From: Thierry Reding <treding@nvidia.com> 
Sent: Wednesday, April 1, 2020 8:20 AM
To: Tom Warren <TWarren@nvidia.com>
Cc: Peter Robinson <pbrobinson@gmail.com>; tomcwarren3959 at gmail.com; u-boot at lists.denx.de; Stephen Warren <swarren@nvidia.com>; Jonathan Hunter <jonathanh@nvidia.com>; Vishruth Jain <vishruthj@nvidia.com>
Subject: Re: [PATCH 3/3] ARM: tegra: p2371-2180: add I2C nodes to DT

On Wed, Apr 01, 2020 at 02:03:09AM +0200, Tom Warren wrote:
> -----Original Message-----
> From: Peter Robinson <pbrobinson@gmail.com>
> Sent: Tuesday, March 31, 2020 3:54 AM
> To: tomcwarren3959 at gmail.com
> Cc: u-boot at lists.denx.de; Stephen Warren <swarren@nvidia.com>; Thierry 
> Reding <treding@nvidia.com>; Jonathan Hunter <jonathanh@nvidia.com>; 
> Tom Warren <TWarren@nvidia.com>; Vishruth Jain <vishruthj@nvidia.com>
> Subject: Re: [PATCH 3/3] ARM: tegra: p2371-2180: add I2C nodes to DT
> 
> External email: Use caution opening links or attachments
> 
> 
> > From: Stephen Warren <swarren@nvidia.com>
> >
> > This adds to the DT the I2C controllers that connect to the board ID 
> > EEPROM, camera board EEPROM, etc. With this change, you can now 
> > probe all I2C devices on a TX1 board.
> >
> > Signed-off-by: Tom Warren <twarren@nvidia.com>
> > ---
> >  arch/arm/dts/tegra210-p2371-2180.dts | 18 ++++++++++++++++++
> >  1 file changed, 18 insertions(+)
> >
> > diff --git a/arch/arm/dts/tegra210-p2371-2180.dts
> > b/arch/arm/dts/tegra210-p2371-2180.dts
> > index c2f497c..d982b5f 100644
> > --- a/arch/arm/dts/tegra210-p2371-2180.dts
> > +++ b/arch/arm/dts/tegra210-p2371-2180.dts
> > @@ -12,6 +12,9 @@
> >
> >         aliases {
> >                 i2c0 = "/i2c at 7000d000";
> > +               i2c2 = "/i2c at 7000c400";
> > +               i2c3 = "/i2c at 7000c500";
> > +               i2c5 = "/i2c at 546c0c00";
> 
> I don't think this is correct, it doesn't show up in U-Boot with the 
> "i2c bus" command where the others do, looking in the tegra210.dtsi it 
> looks like it should be i2c at 546c0000?
> [Tom] That I2C address is working in downstream (L4T) TX1 U-Boot.  The 
> VI_I2C controller is a little weird, it's normal I2C registers are 
> offset from base by 0xC00.  A different driver is needed, but I 
> haven't posted it yet upstream.  I should probably drop if from the 
> DTS for now until I post the VI_I2C driver.

I think the problem here is that the upstream U-Boot device tree doesn't contain an i2c at 546c0c00 node. Instead it has i2c at 546c0000, which we also have in the upstream kernel. My recollection is that that's also the address listed in the Tegra210 system address map of the TRM and there are some registers before the regular I2C interface at offset 0xc00.

I've been carrying a patch against the upstream Linux I2C controller driver to special-case the VI/I2C to always add that 0xc00 offset when accessing registers, which allows us to reuse the existing driver and at the same time keeps all registers mapped so we can also access the VI/I2C specific registers.

My recollection is that the U-Boot driver is fairly similar to the Linux driver, so I suspect something similar could be done.

Thierry
[Tom] Thanks, Thierry. That's my recollection, too, about the VI_I2C 0xC00 offset. I'll take a look at what we have in L4T U-Boot for T210 and address it in a set of patches for upstream soon.  That I2C controller isn't used for anything on any Jetson board except on TX1, I believe, where it allows U-Boot to talk to the camera add-in board to read the board ID. But we've moved all that out to CBoot (board ID EEPROM reading), so there isn't a pressing need for it in U-Boot anymore, IIRC.

--nvpublic

[PATCH 3/3] ARM: tegra: p2371-2180: add I2C nodes to DT

[Thierry Reding]

On Wed, Apr 01, 2020 at 10:35:23PM +0200, Tom Warren wrote:
> -----Original Message-----
> From: Thierry Reding <treding@nvidia.com> 
> Sent: Wednesday, April 1, 2020 8:20 AM
> To: Tom Warren <TWarren@nvidia.com>
> Cc: Peter Robinson <pbrobinson@gmail.com>; tomcwarren3959 at gmail.com; u-boot at lists.denx.de; Stephen Warren <swarren@nvidia.com>; Jonathan Hunter <jonathanh@nvidia.com>; Vishruth Jain <vishruthj@nvidia.com>
> Subject: Re: [PATCH 3/3] ARM: tegra: p2371-2180: add I2C nodes to DT
> 
> On Wed, Apr 01, 2020 at 02:03:09AM +0200, Tom Warren wrote:
> > -----Original Message-----
> > From: Peter Robinson <pbrobinson@gmail.com>
> > Sent: Tuesday, March 31, 2020 3:54 AM
> > To: tomcwarren3959 at gmail.com
> > Cc: u-boot at lists.denx.de; Stephen Warren <swarren@nvidia.com>; Thierry 
> > Reding <treding@nvidia.com>; Jonathan Hunter <jonathanh@nvidia.com>; 
> > Tom Warren <TWarren@nvidia.com>; Vishruth Jain <vishruthj@nvidia.com>
> > Subject: Re: [PATCH 3/3] ARM: tegra: p2371-2180: add I2C nodes to DT
> > 
> > External email: Use caution opening links or attachments
> > 
> > 
> > > From: Stephen Warren <swarren@nvidia.com>
> > >
> > > This adds to the DT the I2C controllers that connect to the board ID 
> > > EEPROM, camera board EEPROM, etc. With this change, you can now 
> > > probe all I2C devices on a TX1 board.
> > >
> > > Signed-off-by: Tom Warren <twarren@nvidia.com>
> > > ---
> > >  arch/arm/dts/tegra210-p2371-2180.dts | 18 ++++++++++++++++++
> > >  1 file changed, 18 insertions(+)
> > >
> > > diff --git a/arch/arm/dts/tegra210-p2371-2180.dts
> > > b/arch/arm/dts/tegra210-p2371-2180.dts
> > > index c2f497c..d982b5f 100644
> > > --- a/arch/arm/dts/tegra210-p2371-2180.dts
> > > +++ b/arch/arm/dts/tegra210-p2371-2180.dts
> > > @@ -12,6 +12,9 @@
> > >
> > >         aliases {
> > >                 i2c0 = "/i2c at 7000d000";
> > > +               i2c2 = "/i2c at 7000c400";
> > > +               i2c3 = "/i2c at 7000c500";
> > > +               i2c5 = "/i2c at 546c0c00";
> > 
> > I don't think this is correct, it doesn't show up in U-Boot with the 
> > "i2c bus" command where the others do, looking in the tegra210.dtsi it 
> > looks like it should be i2c at 546c0000?
> > [Tom] That I2C address is working in downstream (L4T) TX1 U-Boot.  The 
> > VI_I2C controller is a little weird, it's normal I2C registers are 
> > offset from base by 0xC00.  A different driver is needed, but I 
> > haven't posted it yet upstream.  I should probably drop if from the 
> > DTS for now until I post the VI_I2C driver.
> 
> I think the problem here is that the upstream U-Boot device tree
> doesn't contain an i2c at 546c0c00 node. Instead it has i2c at 546c0000,
> which we also have in the upstream kernel. My recollection is that
> that's also the address listed in the Tegra210 system address map of
> the TRM and there are some registers before the regular I2C interface
> at offset 0xc00.
> 
> I've been carrying a patch against the upstream Linux I2C controller
> driver to special-case the VI/I2C to always add that 0xc00 offset when
> accessing registers, which allows us to reuse the existing driver and
> at the same time keeps all registers mapped so we can also access the
> VI/I2C specific registers.
> 
> My recollection is that the U-Boot driver is fairly similar to the
> Linux driver, so I suspect something similar could be done.
> 
> Thierry
> [Tom] Thanks, Thierry. That's my recollection, too, about the VI_I2C
> 0xC00 offset. I'll take a look at what we have in L4T U-Boot for T210
> and address it in a set of patches for upstream soon.  That I2C
> controller isn't used for anything on any Jetson board except on TX1,
> I believe, where it allows U-Boot to talk to the camera add-in board
> to read the board ID. But we've moved all that out to CBoot (board ID
> EEPROM reading), so there isn't a pressing need for it in U-Boot
> anymore, IIRC.

We've had internal discussions about potentially using the ID EEPROMs to
dynamically modify the kernel DTB at runtime (possibly from U-Boot) in
order to support things like different add-in boards.

For example, we currently enable the DSI output in Linux for Jetson TX1.
However, the Jetson TX1 developer kits don't actually ship with that DSI
display (I don't think they even come with the display add-in card), so
this can lead to confusion. The idea was to have U-Boot probe ID EEPROMs
from several sources to determine what to add to the device tree, so
that the kernel DT *source* would only contain the standard developer
kit hardware, but U-Boot (or something else perhaps) could add in extra
nodes for a display module, or camera add-in board, etc.

Note that this is just a vague idea at this time and nothing concrete
has been done to implement this, yet.

Thierry
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