Re: [PATCH] can: grcan: Add device driver for GRCAN and GRHCAN cores

[Marc Kleine-Budde <mkl@pengutronix.de>]

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On 10/11/2012 01:22 PM, Andreas Larsson wrote:
> On 2012-10-11 12:04, Marc Kleine-Budde wrote:
>> On 10/04/2012 11:45 AM, Marc Kleine-Budde wrote:
>>> Hello,
>>>
>>> On 10/02/2012 04:38 PM, Andreas Larsson wrote:
>>>> This driver supports GRCAN and CRHCAN CAN controllers available in
>>>> the GRLIB
>>>> VHDL IP core library.
>>>>
>>>> Signed-off-by: Andreas Larsson <andreas@gaisler.com>
>>>> ---
>>>>   drivers/net/can/Kconfig  |    6 +
>>>>   drivers/net/can/Makefile |    1 +
>>>>   drivers/net/can/grcan.c  | 1283
>>>> ++++++++++++++++++++++++++++++++++++++++++++++
>>>>   drivers/net/can/grcan.h  |  273 ++++++++++
>>>>   4 files changed, 1563 insertions(+), 0 deletions(-)
>>>>   create mode 100644 drivers/net/can/grcan.c
>>>>   create mode 100644 drivers/net/can/grcan.h
>>>
>>> Some general remarks while scrolling though the driver:
>>> - please provide a device tree binding documentation
>>>    Documentation/devicetree/bindings/net/can/grcan.txt
>>>    and add devicetree-discuss@lists.ozlabs.org on Cc
>>> - please provide a documentation for the sysfs entries:
>>>    Documentation/ABI/testing/sys-XXX-grcan.txt
>>> - please implement a NAPI
>>> - please include the .h file into the C code,
>>>    as the C code is the one and only user of the .h file
>>> - please give every macro a GRCAN_ prefix
>>
>> Your driver should work on little as well as on big endian systems. You
>> need probably two implementations of the grcan_{read,write}_reg
>> functions, you can take the flexcan driver [1] as an example.
> 
> Adding that is easy of course, but that gives the impression of support
> for little endian systems. If the core would be instantiated in a little
> endian fashion in a little endian environment, the DMA accessing parts
> of the hardware would still not work in a little endian system without
> modifications to the hardware design.

Can you add this to the Kconfig help text.

> From the driver point of view either way works for me, but I am not sure
> what is best.

In this case you should limit the driver to big endian systems via kconfig.

Marc
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