BCM2835: SPI on Linux 5.10

[Stefan Wahren]

Hi Deniz,

Am 28.04.21 um 22:51 schrieb Deniz Uğur:
> Hi Stefan,
>
> Thanks for the reply.
>
>> Could you please name the SPI device?
> I can’t say I’m quite sure what you mean. I’m going to use Broadcom 
> AS38-H39E Encoder but just accessing the /dev/spidev0.0 should be enough.

so you actual problem is that there is no /dev/spidevX.X?

I hope it's okay, if i just point you in the right direction [1]. The
"problem" is that the upstream DTS doesn't contain the spidev.

Best regards

[1] - https://yurovsky.github.io/2016/10/07/spidev-linux-devices.html

>
>> How do you want to access it? Via SPI device (userspace) or directly
>> with a SPI protocol driver (kernelspace)?
> User space would be my preferance. But at this point I can be flexible.
>
> Be well.
> Deniz.
>
>> On 28 Apr 2021, at 23:43, Stefan Wahren <stefan.wahren at i2se.com> wrote:
>>
>> Hi Deniz,
>>
>> regarding to the mainline kernel especially for SPI, you are a bit out
>> of the comfort zone. config.txt or raspi-config wont help you here.
>>
>> Could you please name the SPI device?
>>
>> How do you want to access it? Via SPI device (userspace) or directly
>> with a SPI protocol driver (kernelspace)?
>>
>> Regards
>> Stefan
>>
>> Am 28.04.21 um 19:53 schrieb Deniz Uğur:
>>> Hi all,
>>>
>>> I wanted to ask for some guidance on enabling SPI with Linux 5.10 mainline kernel. I’m trying to use EVL RTOS [1] but even without using the Dovetail interface, the vanilla Linux fails to bring up SPI device. There is no error log on /var/log/syslog so I’m not sure what other form of log I can provide.
>>>
>>> I simply configure the kernel with multi_v7_defconfig and compile it using the armhf cross-compiler. After the build, I install the modules, copy the image and appropriate DTB file. On config.txt, I add device_tree and kernel parameters and nothing else. The base image is RaspianOS Lite, so I’ve enabled the SPI interface via raspi-config too. I have also tried it on Debian’s and Ubuntu’s RPi image but none of them changed anything. I think there is a configuration problem or SPI isn’t supported on Linux 5.10 (which I highly doubt). I haven’t touched the defconfig because SPI was already enabled in the config.
>>>
>>> I’ve tested this on RPi 3B and I’m going to test it on 4B this evening.
>>>
>>> I’m highly interested in the comments you guys have on this subject and any possible solution to bring up the SPI device.
>>>
>>> Thanks in advance.
>>> Deniz.
>>>
>>> [1]: https://evlproject.org/
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