On 2024-02-04 6:59 am, Andrea della Porta wrote:
From: Phil Elwell <phil@xxxxxxxxxxxxxxx>
Slave addresses for DMA are meant to be supplied as physical addresses
(contrary to what struct snd_dmaengine_dai_dma_data does). It is up to
the DMA controller driver to perform the translation based on its own
view of the world, as described in Device Tree.
Now that the Pi Device Trees have the correct peripheral mappings,
replace the hacky address munging with phys_to_dma().
Signed-off-by: Phil Elwell <phil@xxxxxxxxxxxxxxx>
---
drivers/dma/bcm2835-dma.c | 23 +++++------------------
1 file changed, 5 insertions(+), 18 deletions(-)
diff --git a/drivers/dma/bcm2835-dma.c b/drivers/dma/bcm2835-dma.c
index 237dcdb8d726..077812eda609 100644
--- a/drivers/dma/bcm2835-dma.c
+++ b/drivers/dma/bcm2835-dma.c
@@ -18,6 +18,7 @@
* Copyright 2012 Marvell International Ltd.
*/
#include <linux/dmaengine.h>
+#include <linux/dma-direct.h>
Please read the comment at the top of that file; this driver is
definitely not a DMA API implementation, and should not be including it.
#include <linux/dma-mapping.h>
#include <linux/dmapool.h>
#include <linux/err.h>
@@ -980,22 +981,12 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_slave_sg(
if (direction == DMA_DEV_TO_MEM) {
if (c->cfg.src_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES)
return NULL;
- src = c->cfg.src_addr;
- /*
- * One would think it ought to be possible to get the physical
- * to dma address mapping information from the dma-ranges DT
- * property, but I've not found a way yet that doesn't involve
- * open-coding the whole thing.
- */
- if (c->is_40bit_channel)
- src |= 0x400000000ull;
+ src = phys_to_dma(chan->device->dev, c->cfg.src_addr);
FWIW I'd argue that abusing DMA API internals like this is even more
hacky than bypassing it entirely. The appropriate public API for setting
up the device end of a transfer is dma_map_resource(). Now, it *is* the
case currently that the dma-direct implementation of that does not take
dma_range_map into account, but that's already an open question:
https://lore.kernel.org/linux-iommu/20220610080802.11147-1-Sergey.Semin@xxxxxxxxxxxxxxxxxxxx/
Thanks,
Robin.
info |= BCM2835_DMA_S_DREQ | BCM2835_DMA_D_INC;
} else {
if (c->cfg.dst_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES)
return NULL;
- dst = c->cfg.dst_addr;
- if (c->is_40bit_channel)
- dst |= 0x400000000ull;
+ dst = phys_to_dma(chan->device->dev, c->cfg.dst_addr);
info |= BCM2835_DMA_D_DREQ | BCM2835_DMA_S_INC;
}
@@ -1064,17 +1055,13 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_dma_cyclic(
if (direction == DMA_DEV_TO_MEM) {
if (c->cfg.src_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES)
return NULL;
- src = c->cfg.src_addr;
- if (c->is_40bit_channel)
- src |= 0x400000000ull;
+ src = phys_to_dma(chan->device->dev, c->cfg.src_addr);
dst = buf_addr;
info |= BCM2835_DMA_S_DREQ | BCM2835_DMA_D_INC;
} else {
if (c->cfg.dst_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES)
return NULL;
- dst = c->cfg.dst_addr;
- if (c->is_40bit_channel)
- dst |= 0x400000000ull;
+ dst = phys_to_dma(chan->device->dev, c->cfg.dst_addr);
src = buf_addr;
info |= BCM2835_DMA_D_DREQ | BCM2835_DMA_S_INC;
