[PATCH v2 3/3] renesas: rcar3: Load the correct device tree

[Marek Vasut]

On 6/14/23 17:40, Detlev Casanova wrote:
> On Wednesday, June 14, 2023 11:32:31 A.M. EDT Marek Vasut wrote:
>> On 6/14/23 17:10, Detlev Casanova wrote:
>>> On Wednesday, June 14, 2023 9:53:14 A.M. EDT Marek Vasut wrote:
>>>> On 6/12/23 21:51, Detlev Casanova wrote:
>>>>> The Renesas R-Car Gen3 boards use different device trees than
>>>>> the default one.
>>>>>
>>>>> This commit uses the sysinfo's board id and revision
>>>>>
>>>>> to determine which linux device tree to load:
>>>>>     * H3 (Starter Kit Premier v2.0): renesas/r8a77951-ulcb.dtb
>>>>>     * H3e (Starter Kit Premier v2.1): renesas/r8a779m1-ulcb.dtb
>>>>
>>>> This is not about loading DTs (as the subject would suggest), this is
>>>> about setting the correct default DT name in environment.
>>>>
>>>>> Signed-off-by: Detlev Casanova <detlev.casanova at collabora.com>
>>>>> ---
>>>>>
>>>>>     board/renesas/ulcb/ulcb.c    | 59
>>>>>     ++++++++++++++++++++++++++++++++++++
>>>>>     configs/rcar3_ulcb_defconfig |  1 +
>>>>>     2 files changed, 60 insertions(+)
>>>>>
>>>>> diff --git a/board/renesas/ulcb/ulcb.c b/board/renesas/ulcb/ulcb.c
>>>>> index 1477750f921..cc78e0952b6 100644
>>>>> --- a/board/renesas/ulcb/ulcb.c
>>>>> +++ b/board/renesas/ulcb/ulcb.c
>>>>> @@ -27,6 +27,7 @@
>>>>>
>>>>>     #include <asm/arch/sh_sdhi.h>
>>>>>     #include <i2c.h>
>>>>>     #include <mmc.h>
>>>>>
>>>>> +#include <sysinfo.h>
>>>>>
>>>>>     DECLARE_GLOBAL_DATA_PTR;
>>>>>
>>>>> @@ -65,6 +66,64 @@ int board_init(void)
>>>>>
>>>>>     	return 0;
>>>>>     
>>>>>     }
>>>>>
>>>>> +int misc_init_r(void)
>>>>> +{
>>>>> +	struct udevice *dev;
>>>>> +	int board_id;
>>>>> +	int rev_major, rev_minor;
>>>>> +	int ret = sysinfo_get(&dev);
>>>>> +
>>>>> +	if (ret) {
>>>>> +		debug("Cannot get sysinfo: %d\n", ret);
>>>>> +		return 0;
>>>>
>>>> Why do we ignore errors here ?
>>>>
>>>>> +	}
>>>>> +
>>>>> +	ret = sysinfo_detect(dev);
>>>>> +	if (ret) {
>>>>> +		debug("Cannot detect sysinfo: %d\n", ret);
>>>>> +		return 0;
>>>>> +	}
>>>>
>>>> Looking at all this, I really have to wonder, wouldn't it be nicer to
>>>> introduce a 'sysinfo' command which provides interface to obtain the
>>>> different properties (like board name, id, revision ...) from U-Boot
>>>> command line, and then script the DT selection in U-Boot shell ?
>>>
>>> Yes, that could be a good option. This is more based on how raspberry pis
>>> are selecting the correct devicetree in `board/raspberrypi/rpi/rpi.c`. It
>>> is either about having simple shell scripts that are similar between
>>> devices and the implementation is "hidden" in C for each platform (maybe
>>> easier to use but less flexible). Or more complex shell scripts with
>>> simpler C implementation (more flexible but having to modify a boot
>>> script can become complicated for users)
>>>
>>> Has this direction choice been discussed in the past already ?
>>
>> The less hard-coded board code (which cannot be updated by the user
>> easily), the better. Scripts can be updated in deployment far easier
>> than the bootloader itself. Hence the push for scripts over custom C code.
> 
> That makes sense. I'll create a new command for this then and use it to select
> the dtb in the ulcb boards script.

Thanks !