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gpio: max7301: fix driver for use with CONFIG_VMAP_STACK 

spi_read() and spi_write() require DMA-safe memory. When
CONFIG_VMAP_STACK is selected, those functions cannot be used
with buffers on stack.

This patch replaces calls to spi_read() and spi_write() by
spi_write_then_read() which doesn't require DMA-safe buffers.

Fixes: 0c36ec3147 ("gpio: gpio driver for max7301 SPI GPIO expander")
Cc: <stable@vger.kernel.org>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
Christophe Leroy 2018-12-07 13:07:55 +00:00 committed by Linus Walleij
parent 00ded24c33
commit abf221d2f5
1 changed files with 3 additions and 9 deletions
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12
drivers/gpio/gpio-max7301.c
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@ -25,7 +25,7 @@ static int max7301_spi_write(struct device *dev, unsigned int reg,
struct spi_device *spi = to_spi_device(dev);
u16 word = ((reg & 0x7F) << 8) | (val & 0xFF);
return spi_write(spi, (const u8 *)&word, sizeof(word));
return spi_write_then_read(spi, &word, sizeof(word), NULL, 0);
}
/* A read from the MAX7301 means two transfers; here, one message each */
@ -37,14 +37,8 @@ static int max7301_spi_read(struct device *dev, unsigned int reg)
struct spi_device *spi = to_spi_device(dev);
word = 0x8000 | (reg << 8);
ret = spi_write(spi, (const u8 *)&word, sizeof(word));
if (ret)
return ret;
/*
* This relies on the fact, that a transfer with NULL tx_buf shifts out
* zero bytes (=NOOP for MAX7301)
*/
ret = spi_read(spi, (u8 *)&word, sizeof(word));
ret = spi_write_then_read(spi, &word, sizeof(word), &word,
sizeof(word));
if (ret)
return ret;
return word & 0xff;