Hi Ard, On Tue, 21 Nov 2023 at 10:31, Ard Biesheuvel <ardb@xxxxxxxxxx> wrote: > > dma-ranges is supposed to handle this, but I'm not sure how well it interoperates with SMMUs (which remap DMA addresses into a virtual address space, and this can both solve and create issues when it comes to DMA address limits). > > Adding a 'no-dma-above-4g' property is a bad idea. Not only does it result in potential inconsistencies wrt 'dma-ranges', it also only describes 32 bits of DMA addressing capability, and other DMA addressing limits exist too (40 bits is also common) OK, thank you for that. We will use dma-ranges for this. Regards, Simon > > > > > On Tue, 21 Nov 2023 at 12:01, Lean Sheng Tan <sheng.tan@xxxxxxxxxxxxx> wrote: >> >> Added Ard for some input on this. >> >> Best Regards, >> Lean Sheng Tan >> >> >> >> 9elements GmbH, Kortumstraße 19-21, 44787 Bochum, Germany >> Email: sheng.tan@xxxxxxxxxxxxx >> Phone: +49 234 68 94 188 >> Mobile: +49 176 76 113842 >> >> Registered office: Bochum >> Commercial register: Amtsgericht Bochum, HRB 17519 >> Management: Sebastian German, Eray Bazaar >> >> Data protection information according to Art. 13 GDPR >> >> >> On Tue, 14 Nov 2023 at 23:17, Simon Glass <sjg@xxxxxxxxxxxx> wrote: >>> >>> Hi, >>> >>> Some devices do not support DMA above 4GB. Is there a way to express >>> this in the devicetree? >>> >>> Should we add sometimes a 'no-dma-above-4g' property? >>> >>> Or should we be using dma-ranges for this? >>> >>> Regards, >>> Simon >>>
