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

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Date:	Mon, 14 Jul 2014 11:19:01 +0900
From:	Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@...achi.com>
To:	Greg KH <gregkh@...uxfoundation.org>
Cc:	One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>,
	Stephen Warren <swarren@...dia.com>,
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	Jingoo Han <jg1.han@...sung.com>, linux-kernel@...r.kernel.org,
	Hidehiro Kawai <hidehiro.kawai.ez@...achi.com>,
	linux-serial@...r.kernel.org, yrl.pp-manager.tt@...achi.com,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Aaron Sierra <asierra@...-inc.com>, Jiri Slaby <jslaby@...e.cz>
Subject: Re: Re: [PATCH V8 2/2] serial/uart/8250: Add tunable RX interrupt
 trigger I/F of FIFO buffers

(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
>>> 2012.
>>>
>>> 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
>> handling...
>>
>> 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?

Sure.

Thank you,
Yoshihiro YUNOMAE

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


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