Re: [PATCH v2 1/2] can: flexcan: Remodel FlexCAN register r/w APIs for big endian FlexCAN controllers. - Marc Kleine-Budde

From: Marc Kleine-Budde <mkl@pengutronix.de>
To: Pankaj Bansal <pankaj.bansal@nxp.com>,
	"wg@grandegger.com" <wg@grandegger.com>,
	"linux-can@vger.kernel.org" <linux-can@vger.kernel.org>
Cc: Varun Sethi <V.Sethi@nxp.com>,
	Poonam Aggrwal <poonam.aggrwal@nxp.com>,
	Bhupesh Sharma <bhupesh.sharma@freescale.com>,
	Sakar Arora <Sakar.Arora@freescale.com>
Subject: Re: [PATCH v2 1/2] can: flexcan: Remodel FlexCAN register r/w APIs for big endian FlexCAN controllers.
Date: Thu, 16 Nov 2017 13:04:38 +0100	[thread overview]
Message-ID: <6b02b1e1-df20-c615-b30a-a5a9cbfacdf3@pengutronix.de> (raw)
In-Reply-To: <AM0PR0402MB3940B601B1AB23500B2B49D0F12E0@AM0PR0402MB3940.eurprd04.prod.outlook.com>

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On 11/16/2017 06:24 AM, Pankaj Bansal wrote:
>> What about this:
>>
>> 	/* set defaults */
>> 	if (of_device_is_compatible(pdev->dev.of_node,
>> 				    "fsl,p1010-flexcan")) {
>> 		priv->read = flexcan_read_be;
>> 		priv->write = flexcan_write_be;
>> 	} else {
>> 		priv->read = flexcan_read_le;
>> 		priv->write = flexcan_write_le;
>> 	}
>>
>> 	if (of_device_is_big_endian()) {
>> 		priv->read = flexcan_read_be;
>> 		priv->write = flexcan_write_be;
>> 	} else {
>> 		priv->read = flexcan_read_le;
>> 		priv->write = flexcan_write_le;
>> 	}
>>
> 
> native-endian : Use this if the hardware "self-adjusts"
>    register endianness based on the CPU's configured endianness.

If someone set the wrong endianess, be it native, litte or big, if it's
wrong, it's wrong.

> I don’t see FlexCAN hardware doing that. That is why we should not use 
> of_device_is_big_endian, and only check for "big-endian".

I don't mind.

Marc

-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
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