On Wed, 2024-08-21 at 10:43 +0200, Marc Kleine-Budde wrote: > On 19.08.2024 16:22:55, Martin Jocic wrote: > > Enabling 64-bit addressing for DMA buffers will prevent issues > > on some memory constrained platforms like e.g. Raspberry Pi 5, > > where the driver won't load because it cannot allocate enough > > continuous memory in the default 32-bit memory address range. > > > > Signed-off-by: Martin Jocic <martin.jocic@xxxxxxxxxx> > > --- > > drivers/net/can/kvaser_pciefd.c | 5 +++++ > > 1 file changed, 5 insertions(+) > > > > diff --git a/drivers/net/can/kvaser_pciefd.c > > b/drivers/net/can/kvaser_pciefd.c > > index a60d9efd5f8d..5885f1ce189d 100644 > > --- a/drivers/net/can/kvaser_pciefd.c > > +++ b/drivers/net/can/kvaser_pciefd.c > > @@ -1104,6 +1104,11 @@ static int kvaser_pciefd_setup_dma(struct > > kvaser_pciefd *pcie) > > > > /* Disable the DMA */ > > iowrite32(0, KVASER_PCIEFD_SRB_ADDR(pcie) + > > KVASER_PCIEFD_SRB_CTRL_REG); > > + > > +#ifdef CONFIG_ARCH_DMA_ADDR_T_64BIT > > + dma_set_mask_and_coherent(&pcie->pci->dev, DMA_BIT_MASK(64)); > > +#endif > > + > > Several other driver first set a 64 bit mask and if this fails they set > a 32 bit mask and then bail out, e.g.: > > https://elixir.bootlin.com/linux/v6.10.6/source/drivers/net/ethernet/intel/i40e/i40e_main.c#L15613 > > > > for (i = 0; i < KVASER_PCIEFD_DMA_COUNT; i++) { > > pcie->dma_data[i] = dmam_alloc_coherent(&pcie->pci->dev, > > KVASER_PCIEFD_DMA_S > > IZE, > > -- > > 2.43.0 > > > > > > > > regards, > Marc > As far as I can tell, the dynamic DMA mapping guide of the Kernel docs seems to advise against this:
