Re: [Qemu-devel] [RFC PATCH] hw: arm: Add basic support for cprman (clock subsystem)

[Guenter Roeck]

On 07/16/2018 02:08 AM, Peter Maydell wrote:
> On 15 July 2018 at 23:06, Guenter Roeck <address@hidden> wrote:
> > Add basic support for BCM283x CPRMAN. Provide support for reading and
> > writing CPRMAN registers and initialize registers with sensible default
> > values. During runtime retain any written values.
> >
> > Basic CPRMAN support is necessary and sufficient to boot Linux on raspi2
> > and raspi3 systems.
>
> I can boot Linux on raspi3 with current upstream's level
> of cprman support:
> https://translatedcode.wordpress.com/2018/04/25/debian-on-qemus-raspberry-pi-3-model/

Yes, as long as you use ttyAMA0 as console. Using ttyS1, which is the real 
console
on raspi3, doesn't work. It doesn't give tracebacks, but it reports

[    8.894257] Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled
[    8.973121] bcm2835-aux-uart 3f215040.serial: unable to register 8250 port - 
-22
[    8.981971] bcm2835-aux-uart: probe of 3f215040.serial failed with error -22

and then there is no console. I have to hack the bcm8250 driver to provide
a dummy clock to get it to work.

> > Signed-off-by: Guenter Roeck <address@hidden>
> > ---
> > I don't seriously expect this patch to get accepted, but I thought
> > it might be valuable enough for others to use it when playing with
> > raspi2 and raspi3 emulations.
>
> I'm not necessarily going to rule it out entirely, but I'm
> definitely not very happy about having a model of hardware
> that's very clearly "do something that Linux likes". I'd
> really rather see hardware documentation here -- presumably
> whoever is writing the Linux drivers has that?

Maybe, but I don't, and I was unable to find it. The published documentation
only lists information for some of the registers (for the general purpose
clocks).

In this context, I can't get mmc to work with ToT Linux on raspi3.

/ # mount /dev/mmcblk0 /mnt
[   47.099074] sdhost-bcm2835 3f202000.mmc: timeout waiting for hardware 
interrupt.
[   57.339803] sdhost-bcm2835 3f202000.mmc: timeout waiting for hardware 
interrupt.
[   57.390449] mmc0: Problem switching card into high-speed mode!
[   67.581559] sdhost-bcm2835 3f202000.mmc: timeout waiting for hardware 
interrupt.
[   67.587832] print_req_error: I/O error, dev mmcblk0, sector 2
[   67.588908] Buffer I/O error on dev mmcblk0, logical block 1, lost sync page 
write
[   67.610307] EXT4-fs (mmcblk0): I/O error while writing superblock
[   67.620842] EXT4-fs (mmcblk0): mount failed
[   77.819114] sdhost-bcm2835 3f202000.mmc: timeout waiting for hardware 
interrupt.
[   88.058917] sdhost-bcm2835 3f202000.mmc: timeout waiting for hardware 
interrupt.
[   98.298937] sdhost-bcm2835 3f202000.mmc: timeout waiting for hardware 
interrupt.
[   98.303554] print_req_error: I/O error, dev mmcblk0, sector 2
[   98.306044] Buffer I/O error on dev mmcblk0, logical block 1, lost sync page 
write

Any idea what the problem might be ?

Thanks,
Guenter