AM5728: Disabling unnecessary peripherals

Adam Lee5

Expert 2345 points

Part Number: AM5728
Other Parts Discussed in Thread: ADS1015, PMP

I'm just trying to understand the extent / responsibility of the Linux device tree node.

For example, I have the SATA nodes disabled like this:

/* No Sata on this device */
&sata_phy {
status = "disabled";
};

&sata {
status = "disabled";
};

However, reading the register shows that the block is still powered and being clocked:

root@sg3:~# devmem2 0x4a002374
/dev/mem opened.
Memory mapped at address 0xb6f11000.
Read at address 0x4A002374 (0xb6f11374): 0x0500C000

Am I expected to manipulate these bits directly to completely disable SATA? Or is there anything else that needs to be done in the Linux DTS (or possibly in U-Boot) to make sure SATA does not get initialized at all?

over 5 years ago

0 Keerthy J over 5 years ago

TI__Guru**** 169740 points

Adam,

Double confirm by adding prints in the probe of SATA driver. Also you can print
the value at u-boot itself.

md 0x4a002374 1

This will let us know if that was something done before kernel.

Best Regards,
Keerthy

0 Adam Lee5 over 5 years ago in reply to Keerthy J

Expert 2345 points

Hello Keerthy, thanks for the response.

Here is the output from U-Boot:

=> md 0x4a002374 1
4a002374: 0500c000 ....

Looks the same as the reading from Linux.

FWIW, I checked for SATA in the boot log and from loaded modules, but nothing returned:

root@sg3:~# lsmod
Module Size Used by
bc_example 16384 0
xhci_plat_hcd 16384 0
xhci_hcd 118784 1 xhci_plat_hcd
usbcore 204800 2 xhci_plat_hcd,xhci_hcd
pru_rproc 20480 0
pruss_intc 16384 1 pru_rproc
unified_kbd 24576 0
pruss 16384 1 pru_rproc
dwc3 69632 0
udc_core 28672 1 dwc3
usb_common 16384 3 udc_core,usbcore,dwc3
bluetooth 335872 2
ecdh_generic 28672 1 bluetooth
bridge 110592 0
stp 16384 1 bridge
llc 16384 2 bridge,stp
snd_soc_omap_hdmi_audio 16384 0
pvrsrvkm 417792 1 bc_example
c_can_platform 16384 0
c_can 20480 1 c_can_platform
can_dev 24576 1 c_can
omap_aes_driver 24576 0
omap_sham 28672 0
omap_wdt 16384 1
pruss_soc_bus 16384 0
ti_vip 45056 0
ti_vpe 24576 0
ti_sc 36864 2 ti_vpe,ti_vip
ti_csc 16384 2 ti_vpe,ti_vip
ti_vpdma 20480 2 ti_vpe,ti_vip
dwc3_omap 16384 0
adv7604 61440 1
v4l2_fwnode 16384 2 ti_vip,adv7604
omap_des 20480 0
ti_ads1015 20480 0
leds_lp8863 16384 0
des_generic 28672 1 omap_des
crypto_engine 16384 2 omap_des,omap_aes_driver
omap_crypto 16384 2 omap_des,omap_aes_driver
omap_remoteproc 20480 0
virtio_rpmsg_bus 20480 0
rpmsg_core 16384 1 virtio_rpmsg_bus
remoteproc 40960 2 pru_rproc,omap_remoteproc
sch_fq_codel 20480 3
sonar_gpio 16384 0
cryptodev 45056 0
cmemk 45056 0
root@sg3:~# lsmod | grep -i sata

root@sg3:~#
root@sg3:~# dmesg | grep -i sata

root@sg3:~#

Which module in the Kernel should I put the prints? I don't believe I have any TI specific SATA drivers:

$ cat .config | grep -i sata
CONFIG_SATA_PMP=y
CONFIG_SATA_AHCI=m
CONFIG_SATA_AHCI_PLATFORM=m
# CONFIG_SATA_INIC162X is not set
# CONFIG_SATA_ACARD_AHCI is not set
# CONFIG_SATA_SIL24 is not set
# CONFIG_SATA_QSTOR is not set
# CONFIG_SATA_SX4 is not set
# SATA SFF controllers with BMDMA
# CONFIG_SATA_DWC is not set
CONFIG_SATA_MV=m
# CONFIG_SATA_NV is not set
# CONFIG_SATA_PROMISE is not set
# CONFIG_SATA_SIL is not set
# CONFIG_SATA_SIS is not set
# CONFIG_SATA_SVW is not set
# CONFIG_SATA_ULI is not set
# CONFIG_SATA_VIA is not set
# CONFIG_SATA_VITESSE is not set

0 Keerthy J over 5 years ago in reply to Adam Lee5

TI__Guru**** 169740 points

Hi Adam,

Quickest way to get to the driver is by searching for the exact compatible string of the node
you tried to disable.

Ex: arch/arm/boot/dts/dra7.dtsi

sata: sata@4a141100 {
compatible = "snps,dwc-ahci";
reg = <0x4a140000 0x1100>, <0x4a141100 0x7>;
interrupts = <GIC_SPI 49 IRQ_TYPE_LEVEL_HIGH>;
phys = <&sata_phy>;
phy-names = "sata-phy";
clocks = <&l3init_clkctrl DRA7_SATA_CLKCTRL 8>;
ti,hwmods = "sata";
ports-implemented = <0x1>;
};

git grep snps,dwc-ahci drivers/
drivers/ata/ahci_platform.c: if (of_device_is_compatible(dev->of_node, "snps,dwc-ahci"))
drivers/ata/ahci_platform.c: { .compatible = "snps,dwc-ahci", },

So drivers/ata/ahci_platform.c is the driver file.

Similarly for sata_phy:

git grep ti,phy-pipe3-sata drivers/
drivers/phy/ti/phy-ti-pipe3.c: .compatible = "ti,phy-pipe3-sata",

drivers/phy/ti/phy-ti-pipe3.c is the file.

Best Regards,
Keerthy

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AM5728: Disabling unnecessary peripherals