On 07/03/2014 10:48 AM, Dong Aisheng wrote: > On Thu, Jul 03, 2014 at 09:12:49AM +0200, Marc Kleine-Budde wrote: >> On 07/03/2014 05:48 AM, Dong Aisheng wrote: >>> On Wed, Jul 02, 2014 at 09:13:07PM +0200, Marc Kleine-Budde wrote: >>>> On 07/02/2014 07:54 PM, Oliver Hartkopp wrote: >>>>> I'm not really familiar with the naming concept in device trees. >>>>> >>>>> What is your opinion about the remarks below? >>>> >>>> The entries in the DT, at least on freescale baords, follow the naming >>>> scheme of the reference manual. E.g. on the mx25 it's can1 and can2: >>>> >>>> can1: can@43f88000 { ... } >>>> can2: can@43f8c000 { ... } >>>> >>>> And on the mx28, its: >>>> >>>> can0: can@80032000 { ... } >>>> can1: can@80034000 { ... } >>>> >>>> Because the imx25 datasheet uses a "1" based counting scheme, while the >>>> imx28 uses a "0" based one. >>>> >>>> So it's best practise to follow the naming and numbering scheme of the >>>> hardware reference manual.....and if you have access to the >>>> documentation of the m_can core, use clock names of the m_can core for >>>> the clock-names property. >>>> >>> >>> Based on my knowledge, device tree allows define phandle name according to >>> the real device name of HW according spec while the device node name should >>> be general(e.g can@80032000 rather than flexcan@80032000). >>> For imx6sx, there are already following entries in >>> arch/arm/boot/dts/imx6sx.dtsi >>> flexcan1: can@02090000 {...} >>> flexcan2: can@02094000 {...} >>> So i'd prefer to define as: >>> m_can1: canfd@020e8000 {...} >>> m_can2: canfd@020f0000 {...} >>> >>> >>> One problem is there're can alias already. >>> aliases { >>> can0 = &flexcan1; >>> can1 = &flexcan2; >>> ... >>> } >>> I'm not sure adding can2&can3 for mcan is properly: >>> aliases { >>> can0 = &flexcan1; >>> can1 = &flexcan2; >>> can2 = &m_can1; >>> can3 = &m_can2; >>> ... >>> } >>> Since the m_can driver does not need to use aliases, >>> so i will not add them. >> >> IMHO It's fine too add the can{2,3} aliases to m_can, too. >> > > I think the main problem for doing this way is that the meaning of id > return by of_alias_get_id may be not persistent. > e.g > For MX6SX > aliases { > can0 = &flexcan1; > can1 = &flexcan2; > can2 = &m_can1; > can3 = &m_can2; > ... > } > > For other platform, it could be: > aliases { > can0 = &m_can1; > can1 = &m_can2; > ... > } > It's hard for driver to use. The driver doesn't make use of it, does it? > And actually the M_CAN driver does not need to use the alias. > So i wonder if it makes sense to add the alias for m_can devices > like that. For example the imx53 has two different SPI units, in the alias section we see: spi0 = &ecspi1; spi1 = &ecspi2; spi2 = &cspi; Marc -- Pengutronix e.K. | Marc Kleine-Budde | Industrial Linux Solutions | Phone: +49-231-2826-924 | Vertretung West/Dortmund | Fax: +49-5121-206917-5555 | Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de |
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