| Message ID | 20220503225104.12108-2-Sergey.Semin@baikalelectronics.ru (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Lorenzo Pieralisi |
| Headers | show |
| Series | dmaengine: dw-edma: Add RP/EP local DMA controllers support | expand |
So I think the big problem pointed out by Robin is that existing DTs might not take this into account. So I think we need to do a little research and at least Cc all maintainers and lists for relevant in-tree DTs for drivers that use dma_map_resource to discuss this.
On Mon, May 09, 2022 at 08:15:52AM +0200, Christoph Hellwig wrote: > So I think the big problem pointed out by Robin is that existing DTs > might not take this into account. I'd say that the biggest problem isn't in the DT part but in the drivers using the dma_map_resource() method since they don't expect the non-uniform DMA-direct mapping can be available. > So I think we need to do a little > research and at least Cc all maintainers and lists for relevant in-tree > DTs for drivers that use dma_map_resource to discuss this. Right. I'll send the next patchset revision out with all possibly interested maintainers and lists in Cc of this patch. -Sergey >
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c index 9743c6ccce1a..bc06db74dfdb 100644 --- a/kernel/dma/direct.c +++ b/kernel/dma/direct.c @@ -497,7 +497,7 @@ int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, int nents, dma_addr_t dma_direct_map_resource(struct device *dev, phys_addr_t paddr, size_t size, enum dma_data_direction dir, unsigned long attrs) { - dma_addr_t dma_addr = paddr; + dma_addr_t dma_addr = phys_to_dma_direct(dev, paddr); if (unlikely(!dma_capable(dev, dma_addr, size, false))) { dev_err_once(dev,
A basic device-specific linear memory mapping was introduced back in commit ("dma: Take into account dma_pfn_offset") as a single-valued offset preserved in the device.dma_pfn_offset field, which was initialized for instance by means of the "dma-ranges" DT property. Afterwards the functionality was extended to support more than one device-specific region defined in the device.dma_range_map list of maps. But all of these improvements concerned a single pointer, page or sg DMA-mapping methods, while the system resource mapping function turned to miss the corresponding modification. Thus the dma_direct_map_resource() method now just casts the CPU physical address to the device DMA address with no dma-ranges-based mapping taking into account, which is obviously wrong. Let's fix it by using the phys_to_dma_direct() method to get the device-specific bus address from the passed memory resource for the case of the directly mapped DMA. Fixes: 25f1e1887088 ("dma: Take into account dma_pfn_offset") Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru> --- kernel/dma/direct.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)