I have been doing some testing with the overlay patches and, while it
is working in general, I have noticed a couple of issues.
I am using the following patchsets in conjunction with an updated DTC compiler:
* Device Tree Overlays (v8)
* of: Resolver and dynamic updates
* configfs: Implement binary attributes (v3)
I have applied all 3 of the patchsets against rev
f7e87a44ef60ad379e39b45437604141453bf0ec of the linux source tree.
This is the rev that was specified in the submission of the v8 Device
Tree Overlay patchset.
My base dtb has a SPI bus set up, including chip selects, but
disabled. My overlay dtb enables that bus and adds 3 spi devices. My
overlay is installed in /lib/firmware/port1_gpio.dtbo. The relevant
portion of my base dtb follows:
91 /* runs to Accessory Port 1 */
92 spi0: spi@f0000000 {
93 status = "disabled";
94 cs-gpios = <&pioA 4 0>, <&pioA 2 0>, <&pioA 5 0>, <0>;
95 };
Overlay contents are as follows:
/dts-v1/;
/plugin/;
/* enable spi0 for mts-io */
/ {
fragment@0 {
target-path = "/ahb/apb/spi@f0000000";
__overlay__ {
status = "okay";
ap1-cs0@0 {
compatible = "mts-io-ap1-adc";
spi-max-frequency = <20000000>;
reg = <0>;
};
ap1-cs1@1 {
compatible = "mts-io-ap1-dout";
spi-max-frequency = <1000000>;
reg = <1>;
};
ap1-cs2@2 {
compatible = "mts-io-ap1-din";
spi-max-frequency = <1000000>;
reg = <2>;
};
};
};
};
I have added the following patch in order to more easily demonstrate
what I've observed. This change affects the function spi_add_device()
Index: git/drivers/spi/spi.c
===================================================================
--- git.orig/drivers/spi/spi.c 2014-11-13 07:41:14.424270598 -0600
+++ git/drivers/spi/spi.c 2014-11-13 08:34:24.700331795 -0600
@@ -424,6 +424,8 @@
/* Set the bus ID string */
spi_dev_set_name(spi);
+ dev_info(dev, "adding spi device - chip select [%d]", spi->chip_select);
+
/* We need to make sure there's no other device with this
* chipselect **BEFORE** we call setup(), else we'll trash
* its configuration. Lock against concurrent add() calls.
Applying the overlay from above gives the following output:
root@mtr2d2:~# mount -t configfs none /config/
root@mtr2d2:~# cd /config/device-tree/overlays/
root@mtr2d2:/config/device-tree/overlays# mkdir port1
root@mtr2d2:/config/device-tree/overlays# echo port1_gpio.dtbo > port1/path
atmel_spi f0000000.spi: version: 0x212
atmel_spi f0000000.spi: Using dma0chan2 (tx) and dma0chan3 (rx) for
DMA transfers
atmel_spi f0000000.spi: Atmel SPI Controller at 0xf0000000 (irq 142)
atmel_spi f0000000.spi: adding spi device - chip select [2]
atmel_spi f0000000.spi: adding spi device - chip select [1]
atmel_spi f0000000.spi: adding spi device - chip select [0]
atmel_spi f0000000.spi: adding spi device - chip select [0]
atmel_spi f0000000.spi: chipselect 0 already in use
spi_master spi32766: spi_device register error /ahb/apb/spi@f0000000/ap1-cs0@0
of_spi_notify: failed to create for '/ahb/apb/spi@f0000000/ap1-cs0@0'
__of_changeset_entry_notify: notifier error @/ahb/apb/spi@f0000000/ap1-cs0@0
atmel_spi f0000000.spi: adding spi device - chip select [1]
atmel_spi f0000000.spi: chipselect 1 already in use
spi_master spi32766: spi_device register error /ahb/apb/spi@f0000000/ap1-cs1@1
of_spi_notify: failed to create for '/ahb/apb/spi@f0000000/ap1-cs1@1'
__of_changeset_entry_notify: notifier error @/ahb/apb/spi@f0000000/ap1-cs1@1
atmel_spi f0000000.spi: adding spi device - chip select [2]
atmel_spi f0000000.spi: chipselect 2 already in use
spi_master spi32766: spi_device register error /ahb/apb/spi@f0000000/ap1-cs2@2
of_spi_notify: failed to create for '/ahb/apb/spi@f0000000/ap1-cs2@2'
__of_changeset_entry_notify: notifier error @/ahb/apb/spi@f0000000/ap1-cs2@2
It appears that the spi devices are getting added twice. Despite the
warnings and errors from the overlay driver and the spi subsystem, my
spi devices are working properly.
Attempts to apply additional overlays succeed, but generate an additional error:
root@mtr2d2:/config/device-tree/overlays# mkdir port2
root@mtr2d2:/config/device-tree/overlays# echo port2_gpio.dtbo > port2/path
atmel_spi f0004000.spi: version: 0x212
atmel_spi f0004000.spi: Using dma1chan0 (tx) and dma1chan1 (rx) for
DMA transfers
atmel_spi f0004000.spi: Atmel SPI Controller at 0xf0004000 (irq 143)
atmel_spi f0004000.spi: adding spi device - chip select [2]
atmel_spi f0004000.spi: adding spi device - chip select [1]
atmel_spi f0004000.spi: adding spi device - chip select [0]
atmel_spi f0004000.spi: adding spi device - chip select [0]
atmel_spi f0004000.spi: chipselect 0 already in use
spi_master spi32765: spi_device register error /ahb/apb/spi@f0004000/ap1-cs0@0
of_spi_notify: failed to create for '/ahb/apb/spi@f0004000/ap1-cs0@0'
__of_changeset_entry_notify: notifier error @/ahb/apb/spi@f0004000/ap1-cs0@0
atmel_spi f0004000.spi: adding spi device - chip select [1]
atmel_spi f0004000.spi: chipselect 1 already in use
spi_master spi32765: spi_device register error /ahb/apb/spi@f0004000/ap1-cs1@1
of_spi_notify: failed to create for '/ahb/apb/spi@f0004000/ap1-cs1@1'
__of_changeset_entry_notify: notifier error @/ahb/apb/spi@f0004000/ap1-cs1@1
atmel_spi f0004000.spi: adding spi device - chip select [2]
atmel_spi f0004000.spi: chipselect 2 already in use
spi_master spi32765: spi_device register error /ahb/apb/spi@f0004000/ap1-cs2@2
of_spi_notify: failed to create for '/ahb/apb/spi@f0004000/ap1-cs2@2'
__of_changeset_entry_notify: notifier error @/ahb/apb/spi@f0004000/ap1-cs2@2
(NULL device *): Direct firmware load for ort2_gpio.dtbo failed with error -2
-sh: echo: write error: No such file or directory
The first character of the dtbo file name got chomped. Again, despite
the warnings and errors, the devices are successfully created and
functional:
root@mtr2d2:/config/device-tree/overlays# ls /sys/bus/spi/devices/
spi32765.0 spi32765.1 spi32765.2 spi32766.0 spi32766.1 spi32766.2
I haven't seen a lot of traffic around the v8 overlay patchset so far,
so I wanted to report my findings.
Cheers,
Mike Fiore
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