On Fri, Mar 22, 2024 at 05:10:06PM +0100, Niklas Cassel wrote: > On Thu, Mar 14, 2024 at 08:53:44PM +0530, Manivannan Sadhasivam wrote: > > To maintain uniformity across EPF drivers, let's move the DMA > > initialization to EPC init callback. This will also allow us to deinit DMA > > during PERST# assert in the further commits. > > > > For EPC drivers without PERST#, DMA deinit will only happen during driver > > unbind. > > > > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx> > > --- > > Reviewed-by: Niklas Cassel <cassel@xxxxxxxxxx> > > > For the record, I was debugging a problem related to EPF DMA recently > and was dumping the DMA mask for the struct device of the epf driver. > I was a bit confused to see it as 32-bits, even though the EPC driver > has it set to 64-bits. > > The current code works, because e.g., pci_epf_test_write(), etc, > does: > struct device *dma_dev = epf->epc->dev.parent; > dma_map_single(dma_dev, ...); > > but it also means that all EPF drivers will do this uglyness. > This ugliness is required as long as the dmaengine is associated only with the EPC. > > > However, if a EPF driver does e.g. > dma_alloc_coherent(), and sends in the struct *device for the EPF, > which is the most logical thing to do IMO, it will use the wrong DMA > mask. > > Perhaps EPF or EPC code should make sure that the struct *device > for the EPF will get the same DMA mask as epf->epc->dev.parent, > so that EPF driver developer can use the struct *epf when calling > e.g. dma_alloc_coherent(). > Makes sense. I think it can be done during bind() in the EPC core. Feel free to submit a patch if you like, otherwise I'll keep it in my todo list. - Mani -- மணிவண்ணன் சதாசிவம்
