Building this driver with a 64-bit dma_addr_t type results in
a compiler warning:
drivers/tty/serial/stm32-usart.c: In function 'stm32_of_dma_rx_probe':
drivers/tty/serial/stm32-usart.c:746:20: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
drivers/tty/serial/stm32-usart.c: In function 'stm32_of_dma_tx_probe':
drivers/tty/serial/stm32-usart.c:818:20: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
While the type conversion here is harmless, this hints at a different
problem: we pass an __iomem pointer into a DMA engine, which expects
a phys_addr_t. This happens to work because stm32 has no MMU and
ioremap() is an identity mapping here, but it's still an incorrect
API use. Using dma_addr_t is doubly wrong here, because that would
be the result of dma_map_single() rather than the physical address.
Using the mapbase instead fixes multiple issues:
- the warning is gone
- we don't go through ioremap in error
- the cast is gone, making it use the correct resource_size_t/phys_addr_t
type in the process.
Fixes: 3489187204eb ("serial: stm32: adding dma support")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
drivers/tty/serial/stm32-usart.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index 4d3001b77e7e..2adb678a863b 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -743,7 +743,7 @@ static int stm32_of_dma_rx_probe(struct stm32_port *stm32port,
/* Configure DMA channel */
memset(&config, 0, sizeof(config));
- config.src_addr = (dma_addr_t)port->membase + ofs->rdr;
+ config.src_addr = port->mapbase + ofs->rdr;
config.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
ret = dmaengine_slave_config(stm32port->rx_ch, &config);
@@ -815,7 +815,7 @@ static int stm32_of_dma_tx_probe(struct stm32_port *stm32port,
/* Configure DMA channel */
memset(&config, 0, sizeof(config));
- config.dst_addr = (dma_addr_t)port->membase + ofs->tdr;
+ config.dst_addr = port->mapbase + ofs->tdr;
config.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
ret = dmaengine_slave_config(stm32port->tx_ch, &config);
--
2.9.0
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