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V4L/DVB (4609): Improved i2c performance on software bitbang algoritm
Software I2C were using a very conservative value of udelay=16, meaning about 20Kbps. According with Philips I2C datasheet, the i2c should answer well for times at the order of 4.7 us. So, using udelay=5 should work for all devices. After this patch, the speed should be close to 66,67 Kbps, with the current kernel software bitbang, with 30/60 duty cycle. Anyway, added a new parameter (i2c_udelay) that would allow using conservative values, if eventually a hardware doesn't support the datasheet values. Thanks to Jean Delvare <[email protected]> for pointing this improvement. Signed-off-by: Mauro Carvalho Chehab <[email protected]>
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@ -54,6 +54,12 @@ bttv.o
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dropouts.
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chroma_agc=0/1 AGC of chroma signal, off by default.
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adc_crush=0/1 Luminance ADC crush, on by default.
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i2c_udelay= Allow reduce I2C speed. Default is 5 usecs
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(meaning 66,67 Kbps). The default is the
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maximum supported speed by kernel bitbang
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algoritm. You may use lower numbers, if I2C
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messages are lost (16 is known to work on
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all supported cards).
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bttv_gpio=0/1
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gpiomask=
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