threeeye
bc1d038eac
Squashed backup commit (no shallow-clone history issues) of xiaomi-mt6833-dev/kernel_xiaomi_mt6833 (lineage-23.2 branch, upstream commit 9eece662e) plus all fixes applied to get everpal_defconfig building clean against a modern (GCC 15.2.0) toolchain -- see the previous commit message on the lineage-23.2 branch (also in this repo history is not available here since this is a squashed snapshot; full incremental history lives in the local DL380 checkout and the upstream GitHub remote). Upstream: https://github.com/xiaomi-mt6833-dev/kernel_xiaomi_mt6833 (lineage-23.2)
17 lines
884 B
Plaintext
17 lines
884 B
Plaintext
SPI Chip Select behavior:
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With the Blackfin on-chip SPI peripheral, there is some logic tied to the CPHA
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bit whether the Slave Select Line is controlled by hardware (CPHA=0) or
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controlled by software (CPHA=1). However, the Linux SPI bus driver assumes that
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the Slave Select is always under software control and being asserted during
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the entire SPI transfer. - And not just bits_per_word duration.
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In most cases you can utilize SPI MODE_3 instead of MODE_0 to work-around this
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behavior. If your SPI slave device in question requires SPI MODE_0 or MODE_2
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timing, you can utilize the GPIO controlled SPI Slave Select option instead.
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In this case, you should use GPIO based CS for all of your slaves and not just
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the ones using mode 0 or 2 in order to guarantee correct CS toggling behavior.
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You can even use the same pin whose peripheral role is a SSEL,
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but use it as a GPIO instead.
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