On Mon, Nov 18, 2024, at 08:51, Jacky Chou wrote:
>> Is there a way to probe the presence of 64-bit addressing from hardware
>> registers? That would be nicer than triggering it from the compatible string,
>> given that any future SoC is likely also 64-bit.
I just realized I replied to the wrong email, I meant to send
my question as a reply to patch 4/7. The patch for the pin strap
looks fine.
> There is no register indicated about 64-bit address support in the
> ftgmac100 of Aspeed 7th generation. Therefore, we use the compatible
> to configure pin strap and DMA mask.
Later in the series you just unconditionally write the 64-bit
address, so it appears that the ftgmac100 can actually do
64-bti addressing all along, and this doesn't have to be
conditional at all, the call to dma_set_mask_and_coherent()
only tells the kernel that the device can do it, which should
work on all of them. Since the other devices won't have a
larger "dma-ranges" configuration in DT, and no RAM above
32-bit addressing, it should have no effect.
Just make that part in patch 5 unconditional.
Arnd
