Hi,
On 7/8/20 5:35 AM, Nicolas Saenz Julienne wrote:
Hi Jim,
On Tue, 2020-07-07 at 17:08 -0500, Jeremy Linton wrote:
Hi,
I spun this up on my 8G model using the PFTF firmware from:
https://github.com/pftf/RPi4/releases
Which allows me to switch between ACPI/DT on the machine. In DT mode it
works fine now,
Nice, would that count as a Tested-by from you?
If it worked... :)
but with ACPI I continue to have failures unless I
disable CMA via cma=0 on the kernel command line.
Yes, I see why, in atomic_pool_expand() memory is allocated from CMA without
checking its correctness. That calls for a separate fix. I'll try to think of
something.
It think that is because
using DT:
[ 0.000000] Reserved memory: created CMA memory pool at
0x0000000037400000, size 64 MiB
using ACPI:
[ 0.000000] cma: Reserved 64 MiB at 0x00000000f8000000
Which is AFAIK because the default arm64 CMA allocation is just below
the arm64_dma32_phys_limit.
As I'm sure you know, we fix the CMA address trough DT, isn't that possible
trough ACPI?
Well there isn't a linux specific cma location property in ACPI. There
are various ways to infer the information, like looking for the lowest
_DMA() range and using that to lower the arm64_dma32_phys_limit. OTOH,
as it stands I don't think that information is available early enough to
setup the cma pool.
But as you mention the atomic pool code is allocating from CMA under the
assumption that its going to be below the GFP_DMA range, which might not
be generally true (due to lack of DT cma properties too?).