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ASoC: loongson: fix address space confusion

Message ID 20230622101235.3230941-1-arnd@kernel.org
State New
Headers show
Series ASoC: loongson: fix address space confusion | expand

Commit Message

Arnd Bergmann June 22, 2023, 10:12 a.m. UTC 
From: Arnd Bergmann <arnd@arndb.de>

The i2s driver uses the mapped __iomem address of the FIFO as the DMA
address for the device. This apparently works on loongarch because of
the way it handles __iomem pointers as aliases of physical addresses,
but this is not portable to other architectures and causes a compiler
warning when dma addresses are not the same size as pointers:

sound/soc/loongson/loongson_i2s_pci.c: In function 'loongson_i2s_pci_probe':
sound/soc/loongson/loongson_i2s_pci.c:110:29: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
  110 |         tx_data->dev_addr = (dma_addr_t)i2s->reg_base + LS_I2S_TX_DATA;
      |                             ^
sound/soc/loongson/loongson_i2s_pci.c:113:29: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
  113 |         rx_data->dev_addr = (dma_addr_t)i2s->reg_base + LS_I2S_RX_DATA;
      |                             ^

Change the driver to instead use the physical address as stored in the
PCI BAR resource directly. Since 'dev_addr' is a 32-bit address, I think
this results in the same truncated address on loongarch but is otherwise
closer to portable code and avoids the warning.

Fixes: d84881e06836d ("ASoC: Add support for Loongson I2S controller")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
This is only build tested and I don't understand the loongarch specifics
that well, please review or test for actual hardware requirements.
---
 sound/soc/loongson/loongson_i2s_pci.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

'Christoph Hellwig' June 26, 2023, 7:58 a.m. UTC | #1 
On Thu, Jun 22, 2023 at 12:12:22PM +0200, Arnd Bergmann wrote:
> Change the driver to instead use the physical address as stored in the
> PCI BAR resource directly. Since 'dev_addr' is a 32-bit address, I think
> this results in the same truncated address on loongarch but is otherwise
> closer to portable code and avoids the warning.

This gets rid of the warning, but is still broken.
pci_resource_start retuns a resource_size_t, which really is a
phys_addr_t, but certainly no DMA address.  To map PCI(e) resources
for DMA the driver needs to call dma_map_resource.
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Patch

diff --git a/sound/soc/loongson/loongson_i2s_pci.c b/sound/soc/loongson/loongson_i2s_pci.c
index 6dcfb17d3276d..fa90361865c6c 100644
--- a/sound/soc/loongson/loongson_i2s_pci.c
+++ b/sound/soc/loongson/loongson_i2s_pci.c
@@ -107,10 +107,10 @@  static int loongson_i2s_pci_probe(struct pci_dev *pdev,
 	tx_data = &i2s->tx_dma_data;
 	rx_data = &i2s->rx_dma_data;
 
-	tx_data->dev_addr = (dma_addr_t)i2s->reg_base + LS_I2S_TX_DATA;
+	tx_data->dev_addr = pci_resource_start(pdev, 0) + LS_I2S_TX_DATA;
 	tx_data->order_addr = i2s->reg_base + LS_I2S_TX_ORDER;
 
-	rx_data->dev_addr = (dma_addr_t)i2s->reg_base + LS_I2S_RX_DATA;
+	rx_data->dev_addr = pci_resource_start(pdev, 0) + LS_I2S_RX_DATA;
 	rx_data->order_addr = i2s->reg_base + LS_I2S_RX_ORDER;
 
 	tx_data->irq = fwnode_irq_get_byname(fwnode, "tx");