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Commit 0c2a2ae3 authored by Thomas Koeller's avatar Thomas Koeller Committed by Grant Likely
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spi/davinci: Fix clock prescale factor computation 



Computation of the clock prescaler value returned bogus results if
the requested SPI clock was impossible to set. It now sets either
the maximum or minimum clock frequency, as appropriate.

Signed-off-by: default avatarThomas Koeller <thomas.koeller@baslerweb.com>
Signed-off-by: default avatarGrant Likely <grant.likely@secretlab.ca>
parent 41c4221c

drivers/spi/davinci_spi.c

+9 −3
Original line number Original line Diff line number Diff line
@@ -301,7 +301,7 @@ static int davinci_spi_setup_transfer(struct spi_device *spi, 
	struct davinci_spi *davinci_spi;

	struct davinci_spi *davinci_spi;

	struct davinci_spi_platform_data *pdata;

	struct davinci_spi_platform_data *pdata;

	u8 bits_per_word = 0;

	u8 bits_per_word = 0;

	u32 hz = 0, prescale;

	u32 hz = 0, prescale = 0, clkspeed;





	davinci_spi = spi_master_get_devdata(spi->master);

	davinci_spi = spi_master_get_devdata(spi->master);

	pdata = davinci_spi->pdata;

	pdata = davinci_spi->pdata;
@@ -338,10 +338,16 @@ static int davinci_spi_setup_transfer(struct spi_device *spi, 
	set_fmt_bits(davinci_spi->base, bits_per_word & 0x1f,

	set_fmt_bits(davinci_spi->base, bits_per_word & 0x1f,

			spi->chip_select);

			spi->chip_select);





	prescale = ((clk_get_rate(davinci_spi->clk) / hz) - 1) & 0xff;

	clkspeed = clk_get_rate(davinci_spi->clk);

	if (hz > clkspeed / 2)

		prescale = 1 << 8;

	if (hz < clkspeed / 256)

		prescale = 255 << 8;

	if (!prescale)

		prescale = ((clkspeed / hz - 1) << 8) & 0x0000ff00;





	clear_fmt_bits(davinci_spi->base, 0x0000ff00, spi->chip_select);

	clear_fmt_bits(davinci_spi->base, 0x0000ff00, spi->chip_select);

	set_fmt_bits(davinci_spi->base, prescale << 8, spi->chip_select);

	set_fmt_bits(davinci_spi->base, prescale, spi->chip_select);





	return 0;

	return 0;

}

}