linux-kernel - Re: [PATCH net-next-2.6 v3] can: Topcliff: PCH

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Message-ID: <000b01cb8b6b$d7542a90$66f8800a@maildom.okisemi.com>
Date:	Wed, 24 Nov 2010 09:09:16 +0900
From:	"Tomoya MORINAGA" <tomoya-linux@....okisemi.com>
To:	"Marc Kleine-Budde" <mkl@...gutronix.de>
Cc:	<andrew.chih.howe.khor@...el.com>,
	<socketcan-core@...ts.berlios.de>,
	"Samuel Ortiz" <sameo@...ux.intel.com>, <margie.foster@...el.com>,
	<netdev@...r.kernel.org>,
	"Christian Pellegrin" <chripell@...e.org>,
	<linux-kernel@...r.kernel.org>, <yong.y.wang@...el.com>,
	<kok.howg.ewe@...el.com>, <joel.clark@...el.com>,
	"David S. Miller" <davem@...emloft.net>,
	"Wolfgang Grandegger" <wg@...ndegger.com>, <qi.wang@...el.com>
Subject: Re: [PATCH net-next-2.6 v3] can: Topcliff: PCH_CAN driver: Add Flow control,

On Monday, November 22, 2010 5:27 PM, Marc Kleine-Budde wrote:
>>>>> Still we have the busy waiting in the TX path. Maybe you can move the
>>>>> waiting before accessing the if[1] and remove the busy waiting here.
>>>> I can't understand your saying.
>>>> For transmitting data, calling pch_can_rw_msg_obj is mandatory.
>>> Yes, but the busy wait is not needed. It should be enough to do the
>>> busy-waiting _before_ accessing the if[1].
>>
>> Do you mean we should create other pch_can_rw_msg_obj which doesn't have busy wait ?
>ACK, and this non busy waiting is use in the TX path. But you add a busy
>wait only function before accessing the if[1] in the TX path.

The "busy waiting" of pch_can_rw_msg_obj is for next processing accesses to Message object.
If deleting this busy waiting, next processing can access to Message object, regardless previous transfer doesn't
complete yet.
Thus, I think, the "busy waiting" is necessary.

---
Thanks,

Tomoya MORINAGA
OKI SEMICONDUCTOR CO., LTD.

----- Original Message ----- 
From: "Marc Kleine-Budde" <mkl@...gutronix.de>
To: "Tomoya MORINAGA" <tomoya-linux@....okisemi.com>
Cc: <andrew.chih.howe.khor@...el.com>; <socketcan-core@...ts.berlios.de>; "Samuel Ortiz" <sameo@...ux.intel.com>;
<margie.foster@...el.com>; <netdev@...r.kernel.org>; "Christian Pellegrin" <chripell@...e.org>;
<linux-kernel@...r.kernel.org>; <yong.y.wang@...el.com>; "Masayuki Ohtake" <masa-korg@....okisemi.com>;
<kok.howg.ewe@...el.com>; <joel.clark@...el.com>; "David S. Miller" <davem@...emloft.net>; "Wolfgang Grandegger"
<wg@...ndegger.com>; <qi.wang@...el.com>
Sent: Monday, November 22, 2010 5:27 PM
Subject: Re: [PATCH net-next-2.6 v3] can: Topcliff: PCH_CAN driver: Add Flow control,


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