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From:   Arnd Bergmann <arnd@kernel.org>
To:     Mark Brown <broonie@kernel.org>,
        Yingkun Meng <mengyingkun@loongson.cn>
Cc:     Arnd Bergmann <arnd@arndb.de>, Liam Girdwood <lgirdwood@gmail.com>,
        Jaroslav Kysela <perex@perex.cz>,
        Takashi Iwai <tiwai@suse.com>, alsa-devel@alsa-project.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH] ASoC: loongson: fix address space confusion
Date:   Thu, 22 Jun 2023 12:12:22 +0200
Message-Id: <20230622101235.3230941-1-arnd@kernel.org>
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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(-)

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");
-- 
2.39.2