Re: Re: [PATCH V8 2/2] serial/uart/8250: Add tunable RX interrupt trigger I/F of FIFO buffers

From: Yoshihiro YUNOMAE
Date: Sun Jul 13 2014 - 22:19:10 EST

(2014/07/13 6:22), Greg KH wrote:
On Thu, Jul 10, 2014 at 04:16:37PM -0700, Greg Kroah-Hartman wrote:
On Thu, Jul 10, 2014 at 03:31:57PM +0100, One Thousand Gnomes wrote:
I really don't like the way that the tty core has been changed to handle
multiple attribute groups, as I feel tty drivers shouldn't be creating
"special" sysfs files, depending on what driver is bound to them.

The intent isn't that it is "special" but that it can be propogated to
others as and when they wish to provide it.

Usually we have handled this using tools like 'stty' and ioctls, right?
Surely there is an ioctl to control the interrupt level, right? Hasn't
this been covered before somehow?

No, and the direction when this started was to use sysfs as we have also
been moving all the other attributes towards sysfs and has been since

TTY devices do have lots of strange attributes and right now many of them
are only programmable by using device tree and rebooting.

Ok. Hm, there has to be a better way to do the group sysfs file

Let me work on this tomorrow and see what I can come up with. We should
be able to use the is_visable() attribute to create/notcreate the
attribute where needed...

Ok, how about this patch instead of your first one?

It creates a new port attribute, attr_group, which you should be able to
set in the 8250 driver if you device needs it. Then the serial core
will handle the dynamic group creation, without relying on a "magic"
number of groups. Very close to your patch, but now it's dynamic, and
no fixed array, and no crazy casting in the
tty_port_register_device_attr() call.

Thank you very much for your patch.
I'll use it as 1st patch in next version.

I have not tested this, only test built the code.

OK, I'll test it.

If it works for you, can you redo your second patch, and then send both
of these back to me so that I can apply them?


Thank you,
Yoshihiro YUNOMAE

Yoshihiro YUNOMAE
Software Platform Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: yoshihiro.yunomae.ez@xxxxxxxxxxx

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