linux-kernel - Re: [PATCH RFC 0/4] leds: extend disk trigger

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Message-ID: <aXqE3tn4ACa9HnwU@ryzen>
Date: Wed, 28 Jan 2026 22:51:26 +0100
From: Niklas Cassel <cassel@...nel.org>
To: Markus Probst <markus.probst@...teo.de>
Cc: Damien Le Moal <dlemoal@...nel.org>, Lee Jones <lee@...nel.org>,
	Pavel Machek <pavel@...nel.org>, Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Jacek Anaszewski <jacek.anaszewski@...il.com>,
	John Garry <john.g.garry@...cle.com>,
	Jason Yan <yanaijie@...wei.com>,
	"James E.J. Bottomley" <James.Bottomley@...senpartnership.com>,
	"Martin K. Petersen" <martin.petersen@...cle.com>,
	Pavel Machek <pavel@....cz>, linux-leds@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-ide@...r.kernel.org, linux-scsi@...r.kernel.org,
	Ian Pilcher <arequipeno@...il.com>
Subject: Re: [PATCH RFC 0/4] leds: extend disk trigger

Hello Markus,

On Wed, Jan 28, 2026 at 03:44:19PM +0000, Markus Probst wrote:
> Something similar with scsi and ata exists. scsi doesn't expose the
> firmware_node and there is no symlink (or other connection that I am
> ware of) between scsi_* and ata_* in sysfs. This means, I cannot map a
> fwnode path to a block device.

Hopefully this might help you:

$ ls -al /sys/class/scsi_device | grep ata
lrwxrwxrwx.  1 root root 0 Jan 29 05:12 4:0:0:0 -> ../../devices/pci0000:00/0000:00:17.0/ata5/host4/target4:0:0/4:0:0:0/scsi_device/4:0:0:0
lrwxrwxrwx.  1 root root 0 Jan 29 05:12 5:0:0:0 -> ../../devices/pci0000:00/0000:00:17.0/ata6/host5/target5:0:0/5:0:0:0/scsi_device/5:0:0:0
lrwxrwxrwx.  1 root root 0 Jan 29 05:12 8:0:0:0 -> ../../devices/pci0000:00/0000:00:17.0/ata9/host8/target8:0:0/8:0:0:0/scsi_device/8:0:0:0
lrwxrwxrwx.  1 root root 0 Jan 29 05:12 9:0:0:0 -> ../../devices/pci0000:00/0000:00:17.0/ata10/host9/target9:0:0/9:0:0:0/scsi_device/9:0:0:0


For a specific device, e.g. 4:0:0:0:

$ realpath /sys/class/scsi_device/4:0:0:0/
/sys/devices/pci0000:00/0000:00:17.0/ata5/host4/target4:0:0/4:0:0:0/scsi_device/4:0:0:0

To get the block device name:
$ ls /sys/class/scsi_device/4:0:0:0/device/block/
sda

or

$ ls /sys/devices/pci0000:00/0000:00:17.0/ata5/host4/target4:0:0/4:0:0:0/scsi_device/4:0:0:0/device/block/
sda


You can parse the port from the path. The above example is port 5.

If using a port multiplier (PM), there can be multiple links/devices per port.


Otherwise, for SATA there should be only one.

$ ls -al /sys/class/ata_port/ata5/device/ | grep link | wc -l
1

$ ls -al /sys/class/ata_port/ata5/device/link5/dev5.0/firmware_node

or

$ ls -al  /sys/class/ata_device/dev5.*/device/firmware_node



For PCI BDF, you can use /dev/disk/by-path/

$ ls -al /dev/disk/by-path/ | grep ata
lrwxrwxrwx.  1 root root   9 Jan 29 05:11 pci-0000:00:17.0-ata-3 -> ../../sda
lrwxrwxrwx.  1 root root   9 Jan 29 05:11 pci-0000:00:17.0-ata-3.0 -> ../../sda
lrwxrwxrwx.  1 root root   9 Jan 29 05:11 pci-0000:00:17.0-ata-4 -> ../../sdb
lrwxrwxrwx.  1 root root   9 Jan 29 05:11 pci-0000:00:17.0-ata-4.0 -> ../../sdb
lrwxrwxrwx.  1 root root   9 Jan 29 05:11 pci-0000:00:17.0-ata-7 -> ../../sdc
lrwxrwxrwx.  1 root root   9 Jan 29 05:11 pci-0000:00:17.0-ata-7.0 -> ../../sdc
lrwxrwxrwx.  1 root root   9 Jan 29 05:11 pci-0000:00:17.0-ata-8 -> ../../sdd
lrwxrwxrwx.  1 root root   9 Jan 29 05:11 pci-0000:00:17.0-ata-8.0 -> ../../sdd

Note that these suffixes do not correlate to the ata port number in /sys/class/ata_*


$ ls -al /sys/class/ata_port/
total 0
drwxr-xr-x.  2 root root 0 Jan 29 05:11 .
drwxr-xr-x. 84 root root 0 Jan 29 05:12 ..
lrwxrwxrwx.  1 root root 0 Nov 19 04:01 ata1 -> ../../devices/pci0000:00/0000:00:11.5/ata1/ata_port/ata1
lrwxrwxrwx.  1 root root 0 Jan 29 05:26 ata10 -> ../../devices/pci0000:00/0000:00:17.0/ata10/ata_port/ata10
lrwxrwxrwx.  1 root root 0 Nov 19 04:01 ata11 -> ../../devices/pci0000:50/0000:50:02.0/0000:51:00.0/ata11/ata_port/ata11
lrwxrwxrwx.  1 root root 0 Nov 19 04:01 ata12 -> ../../devices/pci0000:50/0000:50:02.0/0000:51:00.0/ata12/ata_port/ata12
lrwxrwxrwx.  1 root root 0 Nov 19 04:01 ata13 -> ../../devices/pci0000:50/0000:50:02.0/0000:51:00.0/ata13/ata_port/ata13
lrwxrwxrwx.  1 root root 0 Nov 19 04:01 ata2 -> ../../devices/pci0000:00/0000:00:11.5/ata2/ata_port/ata2
lrwxrwxrwx.  1 root root 0 Jan 29 05:26 ata3 -> ../../devices/pci0000:00/0000:00:17.0/ata3/ata_port/ata3
lrwxrwxrwx.  1 root root 0 Jan 29 05:26 ata4 -> ../../devices/pci0000:00/0000:00:17.0/ata4/ata_port/ata4
lrwxrwxrwx.  1 root root 0 Jan 29 05:26 ata5 -> ../../devices/pci0000:00/0000:00:17.0/ata5/ata_port/ata5
lrwxrwxrwx.  1 root root 0 Jan 29 05:26 ata6 -> ../../devices/pci0000:00/0000:00:17.0/ata6/ata_port/ata6
lrwxrwxrwx.  1 root root 0 Jan 29 05:26 ata7 -> ../../devices/pci0000:00/0000:00:17.0/ata7/ata_port/ata7
lrwxrwxrwx.  1 root root 0 Jan 29 05:26 ata8 -> ../../devices/pci0000:00/0000:00:17.0/ata8/ata_port/ata8
lrwxrwxrwx.  1 root root 0 Jan 29 05:26 ata9 -> ../../devices/pci0000:00/0000:00:17.0/ata9/ata_port/ata9


Kind regards,
Niklas