On Thu, Sep 7, 2017 at 12:57 PM, Marcel Holtmann [off-list ref] wrote:

Hi Rob,

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Signed-off-by: Frédéric Danis <redacted>
---
drivers/tty/serdev/core.c | 99 ++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 94 insertions(+), 5 deletions(-)

[...]

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@@ -404,9 +488,14 @@ int serdev_controller_add(struct serdev_controller *ctrl)
     if (ret)
             return ret;

-     ret = of_serdev_register_devices(ctrl);
-     if (ret)
+     ret_of = of_serdev_register_devices(ctrl);
+     ret_acpi = acpi_serdev_register_devices(ctrl);
+     if (ret_of && ret_acpi) {
+             dev_dbg(&ctrl->dev, "serdev%d no devices registered: of:%d acpi:%d\n",
+                     ctrl->nr, ret_of, ret_acpi);
+             ret = -ENODEV;
             goto out_dev_del;
+     }

     dev_dbg(&ctrl->dev, "serdev%d registered: dev:%p\n",
             ctrl->nr, &ctrl->dev);

Shouldn’t we just consider to always register the controller? Even if there are no devices attached to it.

You argued for the opposite at least in regards to a serdev ldisc. :)
The problem is we use the success or failure here to decide if we
create a tty char dev or not. I guess we could move that decision out
of the core and let the tty code check for devices and decide.

we never got the serdev ldisc working. Is there still an attempt to get this working. I frankly don’t know what is best here.

I did get it somewhat working, but haven't been working on it more.
Here's what I said in my last mail to you:

Okay, I've got this kind of working. I can run "ldattach HCI
/dev/ttyblah" to start the LL driver (nothing attached, just tries
firmware loading), then kill ldattach and remove the serdev device.
And it actually works a 2nd time. I've updated my serdev-ldisc branch
with the fixes. The real question is what have I broken in the tty
device. At least "echo rob > /dev/ttyS1" still works (in qemu) after
attaching and de-attaching.

I pushed out my work to serdev-ldisc-v2 branch on my k.org tree.

Rob