Bug 216320

Summary:	KSZ8794 operation broken
Product:	Drivers	Reporter:	Craig McQueen (craig)
Component:	Network	Assignee:	drivers_network (drivers_network)
Status:	NEW ---
Severity:	normal	CC:	olteanv
Priority:	P1
Hardware:	All
OS:	Linux
Kernel Version:	5.15	Subsystem:
Regression:	No	Bisected commit-id:
Attachments:	keep compatibility with device tree blobs with no phy-mode

Description Craig McQueen 2022-08-03 00:24:12 UTC

After upgrading a Yocto build system from kernel 5.4 to 5.15, I found KSZ8794 switch operation was no longer functional. I got errors such as:

Aug  1 22:23:17 tv999996 kern.err kernel: [   10.770912] ksz8795-switch spi2.0: Unsupported interface: gmii, port: 0
Aug  1 22:23:17 tv999996 kern.warn kernel: [   10.777562] ksz8795-switch spi2.0 wan (uninitialized): validation of gmii with support 0000000,00000000,000062cf and advertisement 0000000,00000000,000062cf failed: -22
Aug  1 22:23:17 tv999996 kern.err kernel: [   10.792874] ksz8795-switch spi2.0 wan (uninitialized): failed to connect to PHY: -EINVAL
Aug  1 22:23:17 tv999996 kern.err kernel: [   10.800978] ksz8795-switch spi2.0 wan (uninitialized): error -22 setting up PHY for tree 0, switch 0, port 0
Aug  1 22:23:17 tv999996 kern.err kernel: [   10.829188] ksz8795-switch spi2.0: Unsupported interface: gmii, port: 1
Aug  1 22:23:17 tv999996 kern.warn kernel: [   10.835821] ksz8795-switch spi2.0 lan2 (uninitialized): validation of gmii with support 0000000,00000000,000062cf and advertisement 0000000,00000000,000062cf failed: -22
Aug  1 22:23:17 tv999996 kern.err kernel: [   10.851156] ksz8795-switch spi2.0 lan2 (uninitialized): failed to connect to PHY: -EINVAL
Aug  1 22:23:17 tv999996 kern.err kernel: [   10.859358] ksz8795-switch spi2.0 lan2 (uninitialized): error -22 setting up PHY for tree 0, switch 0, port 1
Aug  1 22:23:17 tv999996 kern.err kernel: [   10.892821] ksz8795-switch spi2.0: Unsupported interface: gmii, port: 2
Aug  1 22:23:17 tv999996 kern.warn kernel: [   10.899466] ksz8795-switch spi2.0 lan1 (uninitialized): validation of gmii with support 0000000,00000000,000062cf and advertisement 0000000,00000000,000062cf failed: -22
Aug  1 22:23:17 tv999996 kern.err kernel: [   10.914845] ksz8795-switch spi2.0 lan1 (uninitialized): failed to connect to PHY: -EINVAL
Aug  1 22:23:17 tv999996 kern.err kernel: [   10.923052] ksz8795-switch spi2.0 lan1 (uninitialized): error -22 setting up PHY for tree 0, switch 0, port 2

I found that if I reverted commit 2c709e0bdad4d996ec8925b9ee6d5b97458708f1, "net: dsa: microchip: ksz8795: add phylink support", then it worked properly again. The errors I saw were due to the checks in ksz8_validate() that were added in the above commit.

Comment 1 Vladimir Oltean 2022-08-17 14:17:57 UTC

Created attachment 301595 [details]
keep compatibility with device tree blobs with no phy-mode

Comment 2 Vladimir Oltean 2022-08-17 14:19:19 UTC

Hi Craig, I've attached a patch formatted against linux-5.15.y. Can you please confirm that it fixes the problem? The code has changed in the current "net" git tree, so if this works, I'll need to submit a different patch for the current trees, and take care of backporting separately.