Hi Vignesh,
On 10.06.24 10:07, Wadim Egorov wrote:
Add: Daniel Schultz
Am 03.06.24 um 19:41 schrieb Vignesh Raghavendra:
Hi Nathan,
On 29/05/24 04:21, Nathan Morrisson wrote:
Add three overlays to disable the eth phy, rtc, and spi nor. These
overlays will be used to disable device tree nodes for components
that are optionally not populated.
v2:
- Add build time tests in makefile
Nathan Morrisson (4):
arm64: dts: ti: k3-am64-phycore-som: Add serial_flash label
arm64: dts: ti: k3-am6xx-phycore-som: Add overlay to disable eth phy
arm64: dts: ti: k3-am6xx-phycore-som: Add overlay to disable rtc
arm64: dts: ti: k3-am6xx-phycore-som: Add overlay to disabl spi nor
arch/arm64/boot/dts/ti/Makefile | 17 +++++++++++++++++
.../boot/dts/ti/k3-am64-phycore-som.dtsi | 2 +-
.../ti/k3-am6xx-phycore-disable-eth-phy.dtso | 19
+++++++++++++++++++
.../dts/ti/k3-am6xx-phycore-disable-rtc.dtso | 15 +++++++++++++++
.../ti/k3-am6xx-phycore-disable-spi-nor.dtso | 15 +++++++++++++++
5 files changed, 67 insertions(+), 1 deletion(-)
create mode 100644
arch/arm64/boot/dts/ti/k3-am6xx-phycore-disable-eth-phy.dtso
create mode 100644
arch/arm64/boot/dts/ti/k3-am6xx-phycore-disable-rtc.dtso
create mode 100644
arch/arm64/boot/dts/ti/k3-am6xx-phycore-disable-spi-nor.dtso
I am not sure if this a common practice to have overlays to disable
missing components (at least I dont see such dtso in kernel). I would
like to see an what DT maintainers feel as such dtsos can explode in
numbers.
Is this something that U-Boot can detect and fix up for the Linux DT?
Unpopulated SPI flash and RTC should ideally not be an issue as drivers
would gracefully fail albeit with some sort of error msg.
Not so sure about Eth PHYs though.
Also, Are these dtso's mutually exclusive? ie can SoM have SPI flash but
not RTC, have RTC and SPI Flash but no ETH PHY?
Let me explain a little bit why we would like to have those overlays
upstream.
Our SOMs come with a so-called "option tree" to produce one product with
different components. For example, our standard part name for the
phyCORE-AM62x is PCM-071-5432DE11I.A0 and the option tree is located
between PCM-071 and A0. In this particular tree, the fourth character
defines the DDR size with 2GB. If we have a customer with less memory
requirements, we can simply produce the 1GB variant (PCM-071-5431...)
and lower the cost.
Luckily, we can read the TI SOC part number in u-boot and disable
non-existing components like CPU cores, GPUs, etc. in the Linux
device-tree. However, we still need to handle all modifiable parts on
our SOMs. For the phyCORE-AM62x, this would be the DDR size, SPI-NOR
size and flash type (Q/OSPI), and whether the RTC and Ethernet PHY are
populated. The DDR size can be handled completely in SPL, but for
everything else we need to modify our Linux device-tree. The easiest and
cleanest way to do that is by applying overlays, which are located next
to the device-tree. I'm not a fan of letting drivers fail to probe.
Customers with extensive product verifications most likely need to
disable those manually, which is against the idea of buying a
fully-functional SOM. Alternatively, we need to hard-code fixups in our
U-Boot which means some U-Boot/Linux combinations might not boot anymore
or we maintain them in a Phytec repository and never archive fully
upstream status for our products.
Regarding the number of overlays. We use those three plus an additional
one, which we need to upstream too, for the AM62x, AM62Ax, and AM64x.
The upcoming AM62P and AM67 require one additional overlay for an
optional, second EEPROM. In total we need 5 overlays for 5 AM6 products.
Best Regards,
Daniel
