[PATCH v1 0/2] spi: spidev: Add Toradex LAVA HAT

[PATCH v1 0/2] spi: spidev: Add Toradex LAVA HAT

[Francesco Dolcini]

From: Francesco Dolcini <francesco.dolcini@toradex.com>

Add a compatible string for the SPI loopback device present on the
Toradex LAVA HAT test fixture and add it to the spidev driver.

The Toradex LAVA HAT is a board used for automated hardware-in-the-loop
(HIL) testing, it provides several test-related functionalities, and
exists in multiple variants depending on the board it is mated with. The
SPI function is implemented with a loopback on the MISO/MOSI signals.

Link: https://lore.kernel.org/all/20260310133254.GA51497@francesco-nb/
Link: https://lore.kernel.org/all/20260316073547.11437-3-francesco@dolcini.it/

Francesco Dolcini (2):
  dt-bindings: trivial-devices: add toradex,lava-hat-spi
  spi: spidev: Add Toradex LAVA HAT OF compatible

 Documentation/devicetree/bindings/trivial-devices.yaml | 2 ++
 drivers/spi/spidev.c                                   | 2 ++
 2 files changed, 4 insertions(+)

-- 
2.47.3

[PATCH v1 1/2] dt-bindings: trivial-devices: add toradex,lava-hat-spi

[Francesco Dolcini]

From: Francesco Dolcini <francesco.dolcini@toradex.com>

Add a compatible string for the SPI loopback device present on the
Toradex LAVA HAT test fixture.

The Toradex LAVA HAT is a board used for automated hardware-in-the-loop
(HIL) testing, it provides several test-related functionalities, and
exists in multiple variants depending on the board it is mated with. The
SPI function is implemented with a loopback on the MISO/MOSI signals.

As the device can be fully described using only "compatible" and "reg",
it is appropriate to list it under trivial-devices.yaml rather than
introducing a dedicated binding.

The SPI implementation is identical across all Toradex LAVA HAT
variants, so a single compatible string is sufficient.

Link: https://lore.kernel.org/all/20260310133254.GA51497@francesco-nb/
Link: https://lore.kernel.org/all/20260316073547.11437-3-francesco@dolcini.it/
Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
---
 Documentation/devicetree/bindings/trivial-devices.yaml | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/trivial-devices.yaml b/Documentation/devicetree/bindings/trivial-devices.yaml
index 23fd4513933a..95e78ff804af 100644
--- a/Documentation/devicetree/bindings/trivial-devices.yaml
+++ b/Documentation/devicetree/bindings/trivial-devices.yaml
@@ -519,6 +519,8 @@ properties:
           - ti,tps546d24
             # I2C Touch-Screen Controller
           - ti,tsc2003
+            # Toradex Lava Hat SPI
+          - toradex,lava-hat-spi
             # Winbond/Nuvoton H/W Monitor
           - winbond,w83793
 
-- 
2.47.3

[PATCH v1 2/2] spi: spidev: Add Toradex LAVA HAT OF compatible

[Francesco Dolcini]

From: Francesco Dolcini <francesco.dolcini@toradex.com>

Add "toradex,lava-hat-spi" OF compatible, that describes the SPI
interface implemented in the Toradex LAVA HAT. The Toradex
LAVA HAT is a test fixture used in Toradex automated testing lab, it
provides various functionality, including SPI MISO-MOSI loopback on
various SPI interface.

Link: https://lore.kernel.org/all/20260310133254.GA51497@francesco-nb/
Link: https://lore.kernel.org/all/20260316073547.11437-3-francesco@dolcini.it/
Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
---
 drivers/spi/spidev.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c
index 638221178384..2a92dfdc5331 100644
--- a/drivers/spi/spidev.c
+++ b/drivers/spi/spidev.c
@@ -701,6 +701,7 @@ static const struct spi_device_id spidev_spi_ids[] = {
 	{ .name = /* semtech */ "sx1301" },
 	{ .name = /* silabs */ "em3581" },
 	{ .name = /* silabs */ "si3210" },
+	{ .name = /* toradex */ "lava-hat-spi" },
 	{},
 };
 MODULE_DEVICE_TABLE(spi, spidev_spi_ids);
@@ -735,6 +736,7 @@ static const struct of_device_id spidev_dt_ids[] = {
 	{ .compatible = "semtech,sx1301", .data = &spidev_of_check },
 	{ .compatible = "silabs,em3581", .data = &spidev_of_check },
 	{ .compatible = "silabs,si3210", .data = &spidev_of_check },
+	{ .compatible = "toradex,lava-hat-spi", .data = &spidev_of_check },
 	{},
 };
 MODULE_DEVICE_TABLE(of, spidev_dt_ids);
-- 
2.47.3

Re: [PATCH v1 1/2] dt-bindings: trivial-devices: add toradex,lava-hat-spi

[Conor Dooley]

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On Mon, Apr 20, 2026 at 01:45:35PM +0200, Francesco Dolcini wrote:
> From: Francesco Dolcini <francesco.dolcini@toradex.com>
> 
> Add a compatible string for the SPI loopback device present on the
> Toradex LAVA HAT test fixture.
> 
> The Toradex LAVA HAT is a board used for automated hardware-in-the-loop
> (HIL) testing, it provides several test-related functionalities, and
> exists in multiple variants depending on the board it is mated with. The
> SPI function is implemented with a loopback on the MISO/MOSI signals.
> 
> As the device can be fully described using only "compatible" and "reg",
> it is appropriate to list it under trivial-devices.yaml rather than
> introducing a dedicated binding.
> 
> The SPI implementation is identical across all Toradex LAVA HAT
> variants, so a single compatible string is sufficient.
> 
> Link: https://lore.kernel.org/all/20260310133254.GA51497@francesco-nb/
> Link: https://lore.kernel.org/all/20260316073547.11437-3-francesco@dolcini.it/
> Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>

Acked-by: Conor Dooley <conor.dooley@microchip.com>
pw-bot: not-applicable

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Re: [PATCH v1 1/2] dt-bindings: trivial-devices: add toradex,lava-hat-spi

[Krzysztof Kozlowski]

On 20/04/2026 18:02, Conor Dooley wrote:
> On Mon, Apr 20, 2026 at 01:45:35PM +0200, Francesco Dolcini wrote:
>> From: Francesco Dolcini <francesco.dolcini@toradex.com>
>>
>> Add a compatible string for the SPI loopback device present on the
>> Toradex LAVA HAT test fixture.
>>
>> The Toradex LAVA HAT is a board used for automated hardware-in-the-loop
>> (HIL) testing, it provides several test-related functionalities, and
>> exists in multiple variants depending on the board it is mated with. The
>> SPI function is implemented with a loopback on the MISO/MOSI signals.
>>
>> As the device can be fully described using only "compatible" and "reg",
>> it is appropriate to list it under trivial-devices.yaml rather than
>> introducing a dedicated binding.
>>
>> The SPI implementation is identical across all Toradex LAVA HAT
>> variants, so a single compatible string is sufficient.
>>
>> Link: https://lore.kernel.org/all/20260310133254.GA51497@francesco-nb/
>> Link: https://lore.kernel.org/all/20260316073547.11437-3-francesco@dolcini.it/
>> Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
> 
> Acked-by: Conor Dooley <conor.dooley@microchip.com>
> pw-bot: not-applicable


Heh, let's wait. That's a test device, so it won't be ever used in any
final product, right? So not in final DTS?

Then why it's here? I think I directed previously to document it with
the rest of test devices - in incomplete-devices schema?

Best regards,
Krzysztof

Re: [PATCH v1 1/2] dt-bindings: trivial-devices: add toradex,lava-hat-spi

[Conor Dooley]

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On Mon, Apr 20, 2026 at 06:10:08PM +0200, Krzysztof Kozlowski wrote:
> On 20/04/2026 18:02, Conor Dooley wrote:
> > On Mon, Apr 20, 2026 at 01:45:35PM +0200, Francesco Dolcini wrote:
> >> From: Francesco Dolcini <francesco.dolcini@toradex.com>
> >>
> >> Add a compatible string for the SPI loopback device present on the
> >> Toradex LAVA HAT test fixture.
> >>
> >> The Toradex LAVA HAT is a board used for automated hardware-in-the-loop
> >> (HIL) testing, it provides several test-related functionalities, and
> >> exists in multiple variants depending on the board it is mated with. The
> >> SPI function is implemented with a loopback on the MISO/MOSI signals.
> >>
> >> As the device can be fully described using only "compatible" and "reg",
> >> it is appropriate to list it under trivial-devices.yaml rather than
> >> introducing a dedicated binding.
> >>
> >> The SPI implementation is identical across all Toradex LAVA HAT
> >> variants, so a single compatible string is sufficient.
> >>
> >> Link: https://lore.kernel.org/all/20260310133254.GA51497@francesco-nb/
> >> Link: https://lore.kernel.org/all/20260316073547.11437-3-francesco@dolcini.it/
> >> Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
> > 
> > Acked-by: Conor Dooley <conor.dooley@microchip.com>
> > pw-bot: not-applicable
> 
> 
> Heh, let's wait. That's a test device, so it won't be ever used in any
> final product, right? So not in final DTS?
> 
> Then why it's here? I think I directed previously to document it with
> the rest of test devices - in incomplete-devices schema?

Oh it's that, I forgot about this discussion, sorry!

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Re: [PATCH v1 1/2] dt-bindings: trivial-devices: add toradex,lava-hat-spi

[Francesco Dolcini]

On Mon, Apr 20, 2026 at 06:10:08PM +0200, Krzysztof Kozlowski wrote:
> On 20/04/2026 18:02, Conor Dooley wrote:
> > On Mon, Apr 20, 2026 at 01:45:35PM +0200, Francesco Dolcini wrote:
> >> From: Francesco Dolcini <francesco.dolcini@toradex.com>
> >>
> >> Add a compatible string for the SPI loopback device present on the
> >> Toradex LAVA HAT test fixture.
> >>
> >> The Toradex LAVA HAT is a board used for automated hardware-in-the-loop
> >> (HIL) testing, it provides several test-related functionalities, and
> >> exists in multiple variants depending on the board it is mated with. The
> >> SPI function is implemented with a loopback on the MISO/MOSI signals.
> >>
> >> As the device can be fully described using only "compatible" and "reg",
> >> it is appropriate to list it under trivial-devices.yaml rather than
> >> introducing a dedicated binding.
> >>
> >> The SPI implementation is identical across all Toradex LAVA HAT
> >> variants, so a single compatible string is sufficient.
> >>
> >> Link: https://lore.kernel.org/all/20260310133254.GA51497@francesco-nb/
> >> Link: https://lore.kernel.org/all/20260316073547.11437-3-francesco@dolcini.it/
> >> Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
> > 
> > Acked-by: Conor Dooley <conor.dooley@microchip.com>
> > pw-bot: not-applicable
> 
> 
> Heh, let's wait. That's a test device, so it won't be ever used in any
> final product, right? So not in final DTS?

It will be used in various DT overlay, that I plan to send for
inclusion in mainline Linux kernel once we have a way forward. So yes,
there will be DTB files using it.

The need is to be able to test SPI with a mainline Linux kernel, so I am
looking for a solution that works in mainline Linux.

What is the reason to not wanting to have a DT overlay file for a test
device in the Linux kernel? I assume that I would not be able to have an
overlay included, if it uses a compatible that is defined in
incomplete-devices. This was my understanding from
https://lore.kernel.org/all/a3796f8b-f94c-4d0d-a0b9-b2970e43e28d@kernel.org/

> Then why it's here? I think I directed previously to document it with
> the rest of test devices - in incomplete-devices schema?

Because, that would not allow to add it to any DT file, from my
understanding.

I linked here both the email thread in which we discussed the topic
before, and I understood it was ok to send it, given we have an actual
HW for it and we plan to submit DT to support it in mainline Linux.

I see we are running in circle, apologize for that.
What can I do so that we can move forward?

Francesco

Re: [PATCH v1 1/2] dt-bindings: trivial-devices: add toradex,lava-hat-spi

[Krzysztof Kozlowski]

On 21/04/2026 10:38, Francesco Dolcini wrote:
> On Mon, Apr 20, 2026 at 06:10:08PM +0200, Krzysztof Kozlowski wrote:
>> On 20/04/2026 18:02, Conor Dooley wrote:
>>> On Mon, Apr 20, 2026 at 01:45:35PM +0200, Francesco Dolcini wrote:
>>>> From: Francesco Dolcini <francesco.dolcini@toradex.com>
>>>>
>>>> Add a compatible string for the SPI loopback device present on the
>>>> Toradex LAVA HAT test fixture.
>>>>
>>>> The Toradex LAVA HAT is a board used for automated hardware-in-the-loop
>>>> (HIL) testing, it provides several test-related functionalities, and
>>>> exists in multiple variants depending on the board it is mated with. The
>>>> SPI function is implemented with a loopback on the MISO/MOSI signals.
>>>>
>>>> As the device can be fully described using only "compatible" and "reg",
>>>> it is appropriate to list it under trivial-devices.yaml rather than
>>>> introducing a dedicated binding.
>>>>
>>>> The SPI implementation is identical across all Toradex LAVA HAT
>>>> variants, so a single compatible string is sufficient.
>>>>
>>>> Link: https://lore.kernel.org/all/20260310133254.GA51497@francesco-nb/
>>>> Link: https://lore.kernel.org/all/20260316073547.11437-3-francesco@dolcini.it/
>>>> Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
>>>
>>> Acked-by: Conor Dooley <conor.dooley@microchip.com>
>>> pw-bot: not-applicable
>>
>>
>> Heh, let's wait. That's a test device, so it won't be ever used in any
>> final product, right? So not in final DTS?
> 
> It will be used in various DT overlay, that I plan to send for
> inclusion in mainline Linux kernel once we have a way forward. So yes,
> there will be DTB files using it.

Then you need to document it properly and post the DTS.

Toradex LAVA hat is way too generic. No, single compatible string is not
sufficient, please read writing bindings.

Please define exact model and variants.

> 
> The need is to be able to test SPI with a mainline Linux kernel, so I am
> looking for a solution that works in mainline Linux.

incomplete devices do not stop you from that.

But you don't get exceptions because you want to mainline your DTS. Your
need detailed hardware description and precise compatible per each exact
hat ("exists in multiple variants").

Best regards,
Krzysztof

Re: [PATCH v1 1/2] dt-bindings: trivial-devices: add toradex,lava-hat-spi

[Francesco Dolcini]

On Tue, Apr 21, 2026 at 10:46:55AM +0200, Krzysztof Kozlowski wrote:
> On 21/04/2026 10:38, Francesco Dolcini wrote:
> > On Mon, Apr 20, 2026 at 06:10:08PM +0200, Krzysztof Kozlowski wrote:
> >> On 20/04/2026 18:02, Conor Dooley wrote:
> >>> On Mon, Apr 20, 2026 at 01:45:35PM +0200, Francesco Dolcini wrote:
> >>>> From: Francesco Dolcini <francesco.dolcini@toradex.com>
> >>>>
> >>>> Add a compatible string for the SPI loopback device present on the
> >>>> Toradex LAVA HAT test fixture.
> >>>>
> >>>> The Toradex LAVA HAT is a board used for automated hardware-in-the-loop
> >>>> (HIL) testing, it provides several test-related functionalities, and
> >>>> exists in multiple variants depending on the board it is mated with. The
> >>>> SPI function is implemented with a loopback on the MISO/MOSI signals.
> >>>>
> >>>> As the device can be fully described using only "compatible" and "reg",
> >>>> it is appropriate to list it under trivial-devices.yaml rather than
> >>>> introducing a dedicated binding.
> >>>>
> >>>> The SPI implementation is identical across all Toradex LAVA HAT
> >>>> variants, so a single compatible string is sufficient.
> >>>>
> >>>> Link: https://lore.kernel.org/all/20260310133254.GA51497@francesco-nb/
> >>>> Link: https://lore.kernel.org/all/20260316073547.11437-3-francesco@dolcini.it/
> >>>> Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
> >>>
> >>> Acked-by: Conor Dooley <conor.dooley@microchip.com>
> >>> pw-bot: not-applicable
> >>
> >>
> >> Heh, let's wait. That's a test device, so it won't be ever used in any
> >> final product, right? So not in final DTS?
> > 
> > It will be used in various DT overlay, that I plan to send for
> > inclusion in mainline Linux kernel once we have a way forward. So yes,
> > there will be DTB files using it.
> 
> Then you need to document it properly and post the DTS.

Ok, I will.

I can also post the DTS in the next version. In general, my
understanding is that so far when sending a patch to add new compatible
you wanted to see a user of it, whatever is a driver or a DTS file.
Given we have a driver change for this in this series, I assumed it was
ok to not send also a DT file.

> Toradex LAVA hat is way too generic. No, single compatible string is not
> sufficient, please read writing bindings.
> 
> Please define exact model and variants.
> 
> > 
> > The need is to be able to test SPI with a mainline Linux kernel, so I am
> > looking for a solution that works in mainline Linux.
> 
> incomplete devices do not stop you from that.

Do this sentence means that I can send a DT file for inclusion in the
Linux kernel using a compatible documented in incomplete-devices?

> But you don't get exceptions because you want to mainline your DTS. Your
> need detailed hardware description and precise compatible per each exact
> hat ("exists in multiple variants").

Let me get into more details here, before sending a new patch version.

We have various LAVA HAT devices, the difference is that they provide
different features and a different layout, based on the actual carrier
board they are mated with.

We have an "Aquila LAVA HAT", that can be mated with the "Aquila
Development Board", and a "Verdin LAVA HAT", that can be mated with a
"Verdin Dahlia Board".

As an example, you can find the Verdin Dahlia DTS here,
ti/k3-am625-verdin-wifi-dahlia.dts, that can be mated with the "Verdin
LAVA HAT".

The SPI device on both "Aquila LAVA HAT" and "Verdin LAVA HAT", is the
same, no differences. On the Aquila variant we
have two instances of it, while on the Verdin we have only one instance
of it.

So, would we need a compatible like this? 

compatible = "toradex,aquila-lava-hat-spi", "toradex,lava-hat-spi";

or

compatible = "toradex,verdin-lava-hat-spi", "toradex,lava-hat-spi";

The actual implementation on both the HW devices is the same, so the
driver can just probe on "toradex,lava-hat-spi".

Thanks
Francesco

Re: [PATCH v1 1/2] dt-bindings: trivial-devices: add toradex,lava-hat-spi

[Krzysztof Kozlowski]

On 21/04/2026 11:59, Francesco Dolcini wrote:
> 
>> Toradex LAVA hat is way too generic. No, single compatible string is not
>> sufficient, please read writing bindings.
>>
>> Please define exact model and variants.
>>
>>>
>>> The need is to be able to test SPI with a mainline Linux kernel, so I am
>>> looking for a solution that works in mainline Linux.
>>
>> incomplete devices do not stop you from that.
> 
> Do this sentence means that I can send a DT file for inclusion in the
> Linux kernel using a compatible documented in incomplete-devices?

No. You will be testing a mainline DTS + load non-mainline overlay. So
your requirements of "mainline Linux" are fully solved. Overlay is
loaded by bootloader for example and thus your kernel is fully mainline.


> 
>> But you don't get exceptions because you want to mainline your DTS. Your
>> need detailed hardware description and precise compatible per each exact
>> hat ("exists in multiple variants").
> 
> Let me get into more details here, before sending a new patch version.
> 
> We have various LAVA HAT devices, the difference is that they provide
> different features and a different layout, based on the actual carrier
> board they are mated with.
> 
> We have an "Aquila LAVA HAT", that can be mated with the "Aquila
> Development Board", and a "Verdin LAVA HAT", that can be mated with a
> "Verdin Dahlia Board".

Of course, because each device is specific so even the hat must be
specific, unless you have a standard connector like Arduino or RPi.

> 
> As an example, you can find the Verdin Dahlia DTS here,
> ti/k3-am625-verdin-wifi-dahlia.dts, that can be mated with the "Verdin
> LAVA HAT".
> 
> The SPI device on both "Aquila LAVA HAT" and "Verdin LAVA HAT", is the
> same, no differences. On the Aquila variant we
> have two instances of it, while on the Verdin we have only one instance
> of it.
> 
> So, would we need a compatible like this? 
> 
> compatible = "toradex,aquila-lava-hat-spi", "toradex,lava-hat-spi";
> 
> or
> 
> compatible = "toradex,verdin-lava-hat-spi", "toradex,lava-hat-spi";

Yes, assuming that verdin/aquila hat works for EVERY verdin/aquila
board, regardless what SoM or SoC you have there.

Verdin is a SoM family according to:
https://www.toradex.com/computer-on-modules/verdin-arm-family

and I doubt you can attach hat to a SoM. There is no connector on SoM
for the hat... so probably you have a board, like Dahlia.

Best regards,
Krzysztof

Re: [PATCH v1 1/2] dt-bindings: trivial-devices: add toradex,lava-hat-spi

[Francesco Dolcini]

On Tue, Apr 21, 2026 at 12:05:45PM +0200, Krzysztof Kozlowski wrote:
> On 21/04/2026 11:59, Francesco Dolcini wrote:
> > 
> >> Toradex LAVA hat is way too generic. No, single compatible string is not
> >> sufficient, please read writing bindings.
> >>
> >> Please define exact model and variants.
> >>
> >>>
> >>> The need is to be able to test SPI with a mainline Linux kernel, so I am
> >>> looking for a solution that works in mainline Linux.
> >>
> >> incomplete devices do not stop you from that.
> > 
> > Do this sentence means that I can send a DT file for inclusion in the
> > Linux kernel using a compatible documented in incomplete-devices?
> 
> No. You will be testing a mainline DTS + load non-mainline overlay. So
> your requirements of "mainline Linux" are fully solved. Overlay is
> loaded by bootloader for example and thus your kernel is fully mainline.

Ok, I was not clear enough, I am looking to have a solution that is 100% in
mainline.

> >> But you don't get exceptions because you want to mainline your DTS. Your
> >> need detailed hardware description and precise compatible per each exact
> >> hat ("exists in multiple variants").
> > 
> > Let me get into more details here, before sending a new patch version.
> > 
> > We have various LAVA HAT devices, the difference is that they provide
> > different features and a different layout, based on the actual carrier
> > board they are mated with.
> > 
> > We have an "Aquila LAVA HAT", that can be mated with the "Aquila
> > Development Board", and a "Verdin LAVA HAT", that can be mated with a
> > "Verdin Dahlia Board".
> 
> Of course, because each device is specific so even the hat must be
> specific, unless you have a standard connector like Arduino or RPi.
> 
> > 
> > As an example, you can find the Verdin Dahlia DTS here,
> > ti/k3-am625-verdin-wifi-dahlia.dts, that can be mated with the "Verdin
> > LAVA HAT".
> > 
> > The SPI device on both "Aquila LAVA HAT" and "Verdin LAVA HAT", is the
> > same, no differences. On the Aquila variant we
> > have two instances of it, while on the Verdin we have only one instance
> > of it.
> > 
> > So, would we need a compatible like this? 
> > 
> > compatible = "toradex,aquila-lava-hat-spi", "toradex,lava-hat-spi";
> > 
> > or
> > 
> > compatible = "toradex,verdin-lava-hat-spi", "toradex,lava-hat-spi";
> 
> Yes, assuming that verdin/aquila hat works for EVERY verdin/aquila
> board, regardless what SoM or SoC you have there.

This is correct, it's exactly like that.

> Verdin is a SoM family according to:
> https://www.toradex.com/computer-on-modules/verdin-arm-family
> 
> and I doubt you can attach hat to a SoM. There is no connector on SoM
> for the hat... so probably you have a board, like Dahlia.

Correct, the HAT is for the carrier, and the carrier is for the family.

With that clarified I plan to send a v2, with something like
"toradex,verdin-dahlia-lava-hat-spi", "toradex,lava-hat-spi" (for each
carrier board we have) and DTS files where this is used, and properly
documenting the compatibility between the various HW devices.

Thanks,
Francesco