netdev - Re: [MeeGo-Dev][PATCH] Topcliff: Update PCH

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Date:	Fri, 20 Aug 2010 15:01:55 +0900
From:	"Masayuki Ohtake" <masa-korg@....okisemi.com>
To:	"Wolfgang Grandegger" <wg@...ndegger.com>
Cc:	"Wang, Qi" <qi.wang@...el.com>, <arjan@...ux.intel.com>,
	<meego-dev@...go.com>, "Wang, Yong Y" <yong.y.wang@...el.com>,
	<gregkh@...e.de>, <netdev@...r.kernel.org>,
	<socketcan-core@...ts.berlios.de>,
	"Khor, Andrew Chih Howe" <andrew.chih.howe.khor@...el.com>,
	"Morinaga" <morinaga526@....okisemi.com>
Subject: Re: [MeeGo-Dev][PATCH] Topcliff: Update PCH_CAN driver to 2.6.35

Hi Wolfgang,

> >>>> 2. Why don't you use kernel existing kfifo infrastructure? ([2]).
> >>> Just take a look at kfifo.h. This structure has been changed. I remembered
> >> there was a spin_lock from kfifo previously. Currently it's been removed, good.
> >>> OKI-sans, would you please take a look at ./include/linux/kfifo.h, and try to
> >> use this structure and APIs?
> >>
> >> As I see it, the code related to that fifo is not used (== dead code)?
> > I'm not familiar with kfifo structure, and I didn't like it because there need a spin_lock to use it.

We are about to study kfifo infra structure.
I have a question.

It seems all CAN drivers accepted by upstream don't use kfifo infrastructure, right ?
(I couldn't see message with "grep kfifo * in drivers/net/can")

If yes, why should we use the kfifo ?
If no, please show me the kfifo reference driver

Thanks, Ohtake(OKISEMI)
----- Original Message ----- 
From: "Wolfgang Grandegger" <wg@...ndegger.com>
To: "Wang, Qi" <qi.wang@...el.com>
Cc: "Khor, Andrew Chih Howe" <andrew.chih.howe.khor@...el.com>; <socketcan-core@...ts.berlios.de>;
<netdev@...r.kernel.org>; <gregkh@...e.de>; "Wang, Yong Y" <yong.y.wang@...el.com>; "Masayuki Ohtak"
<masa-korg@....okisemi.com>; <meego-dev@...go.com>; <arjan@...ux.intel.com>
Sent: Friday, August 13, 2010 7:58 PM
Subject: Re: [MeeGo-Dev][PATCH] Topcliff: Update PCH_CAN driver to 2.6.35


> On 08/13/2010 02:23 AM, Wang, Qi wrote:
> >> -----Original Message-----
> >> From: Wolfgang Grandegger [mailto:wg@...ndegger.com]
> >> Sent: Thursday, August 12, 2010 5:04 PM
> >> To: Wang, Qi
> >> Cc: Daniel Baluta; Masayuki Ohtak; meego-dev@...go.com;
> >> socketcan-core@...ts.berlios.de; netdev@...r.kernel.org; Khor, Andrew Chih
> >> Howe; gregkh@...e.de; arjan@...ux.intel.com; Wang, Yong Y
> >> Subject: Re: [MeeGo-Dev][PATCH] Topcliff: Update PCH_CAN driver to 2.6.35
> >>
> >> On 08/12/2010 03:42 AM, Wang, Qi wrote:
> >>>> -----Original Message-----
> >>>> From: Daniel Baluta [mailto:daniel.baluta@...il.com]
> >>>> Sent: Wednesday, August 11, 2010 6:37 PM
> >>>> To: Masayuki Ohtak
> >>>> Cc: meego-dev@...go.com; Wolfgang Grandegger;
> >>>> socketcan-core@...ts.berlios.de; netdev@...r.kernel.org; Khor, Andrew
> >> Chih
> >>>> Howe; gregkh@...e.de; arjan@...ux.intel.com; Wang, Qi; Wang, Yong Y
> >>>> Subject: Re: [MeeGo-Dev][PATCH] Topcliff: Update PCH_CAN driver to 2.6.35
> >>>>
> >>>> Hi,
> >>>>
> >>>> 2010/8/11 Masayuki Ohtak <masa-korg@....okisemi.com>:
> >>>>> CAN driver of Topcliff PCH
> >>>>>
> >>>>> Topcliff PCH is the platform controller hub that is going to be used in
> >>>>> Intel's upcoming general embedded platform. All IO peripherals in
> >>>>> Topcliff PCH are actually devices sitting on AMBA bus.
> >>>>> Topcliff PCH has CAN I/F. This driver enables CAN function.
> >>>>>
> >>>>> Signed-off-by: Masayuki Ohtake <masa-korg@....okisemi.com>
> >>>>
> >>>> I have a few questions:
> >>>>
> >>>> 1. Is your code based on Intel's CAN EP80579 ([1]) ?
> >>> No.
> >>
> >> For curiosity, is the controller similar to the OKI MSM9225 or ML9620?
> > The Topcliff IOH is developed by OKI actually.
> >
> >>
> >>>> 2. Why don't you use kernel existing kfifo infrastructure? ([2]).
> >>> Just take a look at kfifo.h. This structure has been changed. I remembered
> >> there was a spin_lock from kfifo previously. Currently it's been removed, good.
> >>> OKI-sans, would you please take a look at ./include/linux/kfifo.h, and try to
> >> use this structure and APIs?
> >>
> >> As I see it, the code related to that fifo is not used (== dead code)?
> > I'm not familiar with kfifo structure, and I didn't like it because there need a spin_lock to use it.
> >>
> >>> Daniel,
> >>>
> >>> We're anxious to integrate those codes now. Perhaps it'll take us quite a long
> >> time to use kfifo. How about implementing it with the next version?
> >>
> >> See above. What do you mean with the next version. The driver posted by
> >> Masayuki is far away from being accepted as it does not yet comply with
> >> the Socket-CAN driver API, to say the least.
> > I've few experience on CAN driver and it's also the first time for OKI-san to write Can driver. Would you please
give us a reference and we'll follow it up. We only read 'can.txt' from kernel document. Thank you for your help in
advance.
>
> You are welcome. I think I/we already gave useful hints on what is
> missing and what examples to follow.
>
> Wolfgang.
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